Mad Physics (Experiments)tag:www.madphysics.com,2007:/exp//12007-06-12T23:35:13ZMovable Type 3.2Dehydrating Sugar with Acidtag:www.madphysics.com,2007:/exp//1.302007-05-28T07:42:53Z2007-06-12T23:35:13ZWhen acid is added to sugar, the result appears to be a smoldering tower of gunk. This classic classroom demonstration is an example of a dehydration reaction. The acid "steals" water from the sugar, turning it into pure carbon. This experiment has a video of the reaction--and explains where all that heat comes from!...Afrooz Familyhttp://www.madphysics.com
When acid is added to sugar, the result appears to be a smoldering tower of gunk. This classic classroom demonstration is an example of a dehydration reaction. The acid "steals" water from the sugar, turning it into pure carbon. This experiment has a video of the reaction--and explains where all that heat comes from!]]>
Many of you may have seen this experiment in school—when you mix plain sugar with sulfuric acid, a violent reaction occurs that leaves you with graphite and a lot of steam, but what’s really happening? First, let’s see what the reaction looks like:
When acid is added to the sugar, the sugar turns black, expands and bubbles while letting off a great deal of steam; however, if both the sugar and acid were at room temperature, where did all of this newfound heat come from? The answer is all in the chemistry of the situation.
The reaction in the video is called an exothermic (from Latin, ex meaning out, and thermein to heat) reaction. More precisely it is a dehydration reaction (a class of elimination reactions). The formula here is:
C12H22O11 (Sugar) + H2SO4 (Sulfuric Acid) → 12C (Graphite) + 11H2O (Water) + A mix of water and acid
As you can see, the reaction is called a dehydration reaction because water is lost (by the sugar), and to balance the equation it must be transferred (the acid is hydrated—“dehydration reaction” is a bit of a misnomer since even though the sugar is dehydrated, that water is “gained” by the acid and doesn’t just disappear). This water transfer is what creates the heat in the reaction. The water and the acid create very strong hydrogen bonds, which in turn give off energy in the form of heat. When bonds break and form energy is often transferred, some bonds are easier to form than others, so often the excess energy that doesn’t go into making bonds, gives off heat energy.
In this reaction when hydrogen and oxygen are taken away from sugar, all we have left is carbon (the black stuff). The water is separated out and escapes mostly as vapor, and like most reactions, not everything is able to react, so we often have unreacted acid evaporating with the water (and making this a very dangerous experiment, have a teacher show you if you are curious, or just enjoy the video).
This lab is often demonstrated in school because it is a good introduction to many general chemistry topics including bond energies, acids, and more.
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2006 Nobel Prize Celebrationtag:www.madphysics.com,2006:/exp//1.292006-10-04T04:18:10Z2007-06-12T23:19:50ZToday the Nobel Committee announced the winners of the 2006 prize for physics. This year's laureates John C. Mather and George F. Smoot won "for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation." Both laureates are in some way associated with the University of California, Berkeley: Mather is an alumnus and Smoot is a professor. Therefore, it is Mad Physics's distinct pleasure to show you our pictures from Smoot's official Nobel Prize reception at the physics department!...Afrooz Familyhttp://www.madphysics.com
Today the Nobel Committee announced the winners of the 2006 prize for physics. This year's laureates John C. Mather and George F. Smoot won "for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation." Both laureates are in some way associated with the University of California, Berkeley: Mather is an alumnus and Smoot is a professor. Therefore, it is Mad Physics's distinct pleasure to show you our pictures from Smoot's official Nobel Prize reception at the physics department!]]>
This year's Nobel Prize of Physics went to two physicists whose contributions to astronomy have greatly deepened our understanding of the Universe. When an announcement is this big, you have to assume that Mad Physics will be there to give you all the details. Below, our party summary!
Nobel Laureate George Smoot was quick to embrace life as a scientific rock star!
This year the Physics Prize is awarded for work that looks back into the infancy of the Universe and attempts to gain some understanding of the origin of galaxies and stars. It is based on measurements made with the help of the COBE satellite launched by NASA in 1989.
The COBE results provided increased support for the Big Bang scenario for the origin of the Universe, as this is the only scenario that predicts the kind of cosmic microwave background radiation measured by COBE. These measurements also marked the inception of cosmology as a precise science. It was not long before it was followed up, for instance by the WMAP satellite, which yielded even clearer images of the background radiation. Very soon the European Planck satellite will be launched in order to study the radiation in even greater detail.
According to the Big Bang scenario, the cosmic microwave background radiation is a relic of the earliest phase of the Universe. Immediately after the big bang itself, the Universe can be compared to a glowing "body emitting radiation in which the distribution across different wavelengths depends solely on its temperature. The shape of the spectrum of this kind of radiation has a special form known as blackbody radiation. When it was emitted the temperature of the Universe was almost 3,000 degrees Centigrade. Since then, according to the Big Bang scenario, the radiation has gradually cooled as the Universe has expanded. The background radiation we can measure today corresponds to a temperature that is barely 2.7 degrees above absolute zero. The Laureates were able to calculate this temperature thanks to the blackbody spectrum revealed by the COBE measurements.
Now for more pictures from the reception:
George Smoot with UC Berkeley Chancellor (and physicist) Robert Birgeneau more pictures of the two below...
Now if you think that such a great day had room for only one Nobel Laureate, you would be wrong. Here are some shots of Laureate Steven Chu:
Finally here are a couple pictures of University of California President (and physicist—do you see a trend here?) Robert Dynes:
It was quite the party! I can't wait until next year!
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Hysteresis and Rubber Bandstag:www.madphysics.com,2006:/exp//1.272006-04-13T21:09:46Z2007-06-12T23:21:35ZAt Mad Physics, we've already shown you the "classical" Hooke's Law Demonstration. Now, here’s an alternate take on the age-old experiment. Rubber bands behave similarly to springs, except that they do not assume their original shape after being stretched. This is because of a phenomenon called hysteresis. We can use this knowledge to calculate the energy lost by the band....Afrooz Familyhttp://www.madphysics.com
At Mad Physics, we've already shown you the "classical" Hooke's Law Demonstration. Now, here’s an alternate take on the age-old experiment. Rubber bands behave similarly to springs, except that they do not assume their original shape after being stretched. This is because of a phenomenon called hysteresis. We can use this knowledge to calculate the energy lost by the band.]]>
Introduction | Design | Results | Analysis | Conclusion
Introduction
When one performs a Hooke’s Law type experiment with a rubber band, it can be noticed that the band does not behave exactly like a spring. A rubber band, made of latex and rubber, does not return to its exact original shape after being stretched. This is an example of a phenomenon called hysteresis. By studying the relationship between the rubber band during stretching and unstretching, one can determine the amount of work done on the rubber band, and the amount of energy (in joules) lost by the band.
Design
A retort stand with clamp should be used to hold a ruler and rubber band. The ruler should be accurate to ± 0.5mm. Masses should be added to the band in increments of 100g. The device holding the masses in this experiment had a mass of 50g; therefore, the progression of masses went: 0g, 50g, 150g, 250g, 350g, etc. up to 1.05kg.
One should use a ruler (or some sort of straight edge) to find the position of the rubber band on the held ruler—this should be done to avoid parallax.
The image (on the left) is a representation of the set up.
To measure data in this experiment, masses should be added slowly and gently. The stretch should be recorded in meters. Once 1.05kg have been added, masses should be removed in the same increments as they were added and the new stretch should be recorded. This data will therefore be split into two sections: stretching and unstretching.
Results
Masses were added from 0-1.05kg and then removed in the same way they were added. Stretch was noted in meters, and mass was noted in kilograms. The following tables represent the raw data with unites and uncertainties:
For the data to be processed mass was converted into force. In doing this conversion, it was assumed that acceleration due to gravity was 10ms-2 and thus 0.25 kg exerted a force of 2.5N on the rubber band.
Analysis
Then, force (N) was plotted against stretch (m) on a xy scatter graph. These variables are important for finding work because work is expressed in Nm (Newton Meters). Thus, if we plot our points and find lines of best fit, we will be able to integrate the function to find the amount of work needed for stretching and unstretching, and the difference in values will indicate the amount of energy lost by the band in joules.
The measurements taken in this lab were taken with degrees of uncertainty (as cited by the collected data). The overall uncertainties were calculated as such:
Graph 3: On the next page is a graph representing the recorded data. The graph contains points (taken off of the raw data), and then a line of best fit. One line represents the stretching process, the other, unstretching. Both lines of best fit are third order polynomial functions, which will be used to find work.
Both fits are >99% accurate in regards to the raw data. This means that the average variance between data points and the line of best is less that a 1% offset. Therefore, the line of best fit can be considered to be a direct representation of the data collected.
These functions will later be integrated (which is better than finding the area under the raw graph which is not smooth).
Integration—finding work done:
The graph above represents the polynomial lines of best fit found for the data. Just as before, the x-axis represents stretch in meters while the y-axis represents force in Newtons. Both functions were integrated to find the area under the curve.
Thus, roughly 1.25J were put into the band to stretch it, and only ~.99J were released to unstretch it, which means that the band lost roughly .26J with a 2% uncertainty.
Conclusion
It is clear from the force curve that the rubber band does not obey Hooke's Law. The force curve for a rubber band is said to be a hysteresis loop, and the area between the two curves represents lost energy.
Some of the work done on the rubber band is against internal friction, which increases the temperature of the rubber band and its surroundings. There is thus less energy available to raise the weights back up.
The rubber band lost ~0.26J ± 2% based on the 10% uncertainty in Force measurements and 0.2% error in stretch.
]]>
Molten Magnesiumtag:www.madphysics.com,2006:/exp/test//1.132005-12-26T18:38:50Z2007-06-12T23:22:05ZAfter a long and arduous exam period, what did we do? Almost set Joost's garage on fire! It wasn't our proudest moment, but it was indicative of magnesium's crazy heat output. Magnesium burns at 2200ºC, which produces an impressive white light....Afrooz Familyhttp://www.madphysics.com
After a long and arduous exam period, what did we do? Almost set Joost's garage on fire! It wasn't our proudest moment, but it was indicative of magnesium's crazy heat output. Magnesium burns at 2200ºC, which produces an impressive white light.
before my
trip, I mean the day of. Emory, the university where I work, didn’t
have any, so I went to Georgia Tech. I bought magnesium in its powder
form. It’s just as fun as the strips, but messier! During my
tour down under, I did demos with the powder, but when I got back I
still had half a bottle left. We put it to good use in this experiment!
Magnesium, the twelfth element, is an alkaline earth metal (group
II) and is represented in 2% of the earth’s crust. Though this
experiment highlights magnesium powder’s flammability, it should
be noted that magnesium, in bulk, is not very flammable. As
we learned in our nondairy
creamer experiment, powders have a propensity
for combustion. Bulk magnesium is popular in industry for its strength
and overall lightness (magnesium is 33% lighter than aluminum). Many
car companies (such as BMW) use magnesium to make their engine blocks.
Other industrial uses for magnesium are hinged on its ability to produce
copious amounts of heat when burnt.
Our experiment was also based on burning magnesium. Magnesium burns
at 2200ºC or roughly 4000ºF, and produces a bright white
light (look at the spots of burning magnesium in the picture below):
Magnesium produces white light because when its excited electrons
fall back to their ground state, they release energy encompassing all of
the Balmer series (i.e. visible light). Because every wavelength of
light is produced, the human eye sees this as one single net result,
white light. However, when we were cleaning our tools after the experiment
we noticed that they were a bit dirty. The results are quite beautiful:
In school laboratories burning magnesium is often demonstrated using
magnesium strips. The reason strips are used being that magnesium
will only burn in small (thin) quantities or in powder form, and
that using powder—as we discovered—can be both messy
and dangerous. We did our experiment in what can be described as
a very thick steel bowl. We used a butane torch to heat corners of
the bowl, and then blow powder onto the hot surface. We then used
hot magnesium to ignite the rest. The result was a bowl full of unburnt
magnesium, burning magnesium, and magnesium oxide (the result of
combustion, a white powder). It should also be noted that magnesium
powder will not burn with a match or lighter. At best there is occasionally
a spark. So, to keep you safe and sound, we recommend that you admire
these videos and keep away from the powder!
Funny/Dangerous Note: This lab isn't
the safest because of the temperatures involved. We found this out
first hand when we accidently blew some of burning magnesium out
of the steel plate, and onto Joost's wooden workbench. Needless
to say, we moved outside after that, but there were quite a few ashes
flying around his garage. This brings me to a side note. If you ever
start a magnesium fire, never put it out with water or a C02 extinguisher.
Water will only feed the fire. This is because water will instantly
vaporize when it touches the fire and will produce magnesium hydroxide:
Mg + 2 H2O → Mg(OH)2 + H2
SInce magnesium can burn in carbon dioxide, one should
only use a class D fire extinguisher (see
our post about fire extinguishers)
or sand or baking powder. Now with that asidem here is a video of
the famous fire, and then our new spot outside:
]]>
Esterification Reactionstag:www.madphysics.com,2006:/exp/test//1.122005-12-05T18:34:42Z2007-06-12T23:22:43ZThis is one of the most technically-involved labs on Mad Physics. The experiment requires fancy laboratory equipment, but nonetheless, the principles behind the experiment are simple and it serves as a great tool to learn about equipment like condensers and distillation columns....Afrooz Familyhttp://www.madphysics.com
This is one of the most technically-involved labs on Mad Physics. The experiment requires fancy laboratory equipment, but nonetheless, the principles behind the experiment are simple and it serves as a great tool to learn about equipment like condensers and distillation columns.
too complicated. Actually, we only got complex in terms
of set up; the chemistry behind this experiment is pretty basic. The
reason we chose to do this though is we thought that if we used this “complicated
equipment” we would familiarize our audience with it, and prove
that the science behind it is simple. Take a look!
In this experiment we took household products—rubbing alcohol
and vinegar—and we did some flashy organic chemistry! This experiment
will familiarize you with laboratory terminology and organic chemistry
terms. Don’t be afraid, this won’t hurt at all! Everything
will be kept at a simple level, and this way you will be more comfortable
talking in scientific language.
The experiment done here (as stated in the title) creates an ester;
therefore, this is, technically speaking, an esterification reaction.
To make the reaction go faster we added a strong acid (sulfuric acid),
the only other things in the mix were alcohol and vinegar. The methods
will detail how we did what, and what it all means. Here is a picture
of our setup:
Fancy, no? To understand better what everything in the picture represents,
keep on reading.
Follow the numbers in the diagram (bottom right to bottom left)
to see what is happening:
1. The experiment begins with the reactants, vinegar
and rubbing alcohol. The vinegar is placed in a 500mL flask in an
excess of rubbing alcohol. Speaking in chemistry terms, our reactants
are acetic acid (vinegar) and ethanol (rubbing alcohol). The equation
for these reactants is: H3C-COOH + HO-CH2-CH
(along with two drops of sulfuric acid).
The
reactants are heated with a Bunsen until they boil. Take a look
at the video below:
2. They vapor then rise up a distillation column. This
column separates vapors based on their pressures. Some of the vapors
condense and go back down into the flask. The rest of the separated
gases continue rising. Notice the video of the droplets forming inside:
3. The vapors are now led up through a connector piece, which feeds,
into the condenser.
4. The condenser is a tube within a tube. The inner tube will allow
the vapors to pass; however, the condenser has a water jacket (i.e.
water passes around the outside). This enables the gases to get cooled,
and turn back into liquids. Notice the video of water passing through
the condenser:
5. The liquid now passes though the connector tube, and fall into
the flask. Notice the droplet here:
6. The liquid collected in the flask should be ethyl
acetate. In reality the products created by the reaction are ethyl
acetate and water. Therefore the products are: H3C-COO-CH2-CH3 +
H2O and the
full process is:
H3C-COOH + HO-CH2-CH3 ⇔ H3C-COO-CH2-CH3
+ H2O
To check to see if you do in fact have an ester, smell your products!
They should smell sweet.]]>
Non Dairy Creamer Free Radicalstag:www.madphysics.com,2006:/exp/test//1.112005-11-14T18:24:19Z2006-03-11T19:37:29ZThe graphic looks almost just like the one below... visually, it may just be another fireball, but the way we made it was completely different. These two labs are great for comparison because one is a more traditional explosion, while this one is hinged on the basics of free radicals....Afrooz Familyhttp://www.madphysics.com
The graphic looks almost just like the one below... visually, it may just be another fireball, but the way we made it was completely different. These two labs are great for comparison because one is a more traditional explosion, while this one is hinged on the basics of free radicals.
Ask any big time farmer about dust explosions and they’ll know
exactly what you mean. Every year, entire “empty” wheat
silos literally explode because of the stuff floating around in the
air. This explosion usually happens when a spark or flame ignites floating
grain—an example of a free radical explosion.
While the last experiment we did (wax fireballs) showed off a thermal
explosion, this experiment is our first free radical explosion. To
understand what a free radical explosion is, one must understand what
a free radical is. Simply put, a free radical is a molecule (or an
atom) with unpaired electrons. These unpaired electrons are very reactive,
and are therefore prone to chemical reactions—such as combustion.
Like we’ve seen many times over on this site, combustion is a
reaction between something and (usually) oxygen. So here is why a free
radical facilitates combustion.
The oxygen we breathe is diatomic (i.e. two oxygen atoms stuck together).
They are held together by double bonds, and so their arrangement is
O=O. For something to combust, or react with oxygen, it must break
the strong double bond between the O’s, this is where free radicals
come into play. Free radicals, being reactive, will readily break this
double bond, and thus enable combustion.
Now, back to non-dairy creamer.
Dairy-creamer, like any powder has a huge surface area.
In fact, if you took a spoonful of powder, it might have a surface
area comparable to the floor plan of your house! This is thanks to
the fact that the particles involved are so small, so the net surface
area is huge. If you have a great surface area, more free radicals
can be formed and, since free radicals determine the rate of the combustion,
you will have a high rate, and thus an explosion will occur. It works
very well if the dust itself is flammable; however, with this example,
you will notice that non-dairy creamer itself will not burn sitting
in a pile. One must scatter it in air for the sides of the particles
(and the free radicals) to be exposed to air.
So in conclusion:
Non-dairy creamer: not flammable on its own, but is flammable when
evenly spread in air.
Don’t believe us? Well here are some videos of
our fire. This is very dangerous (look at Martijn jumping out of
the fire in the first video!); so as usual don’t
try it. We did this off of Joost’s balcony and therefore the
fireball is ~20 feet tall; however, it would have been very easy
to make the fireball bigger. This was impressive enough, and this
was we didn’t
waste too much powder.
The videos are below, they’re big, but it’s worth the
wait.
]]>
20 Foot Wax Fireballtag:www.madphysics.com,2005:/exp/test//1.102005-09-12T18:15:26Z2007-06-12T23:23:57ZJoost and I bought a few expensive pillar candles and we created a giant fireball that was >20 feet tall at its highest point. How did we do it? Well, you'll have to read all about it, or if the text bores you, just check out the amazing videos....Afrooz Familyhttp://www.madphysics.com
Joost and I bought a few expensive pillar candles and we created a giant fireball that was >20 feet tall at its highest point. How did we do it? Well, you'll have to read all about it, or if the text bores you, just check out the amazing videos.
After being inspired by Michael Faraday’s Chemical History
of a Candle Joost and I did some research and he found a rather
nice experiment to do with candles. The result: one of the stupidest
coolest experiments we’ve done.
This lab uses the concepts of phase change and density to create a
giant fireball. The one we made was over twenty feet tall! Our goal
is to maybe redo this experiment on a bigger scale, but for now we’re
still happy to be alive.
This lab is so dangerous you could get hurt watching this video. WE
STRONGLY DISCOURAGE THE BEHAVIOR SEEN HERE. I have been working in
laboratory science for four years and I was wearing a great deal of
protective clothing (see: videos), but I still took a big risk in doing
this experiment. We had first aid, fire extinguishers, and proper gear.
This experiment has a lot of room for mistake, so don’t tempt
fate. But while you’re at it, watch us tempt fate instead:
This is how the experiment works: you create a fire and place candles
(or simply wax) in a metal bucket and place the bucket on the fire.
After some time the wax should melt and catch on fire. Once the wax
is on fire you dump some (hot) water into the bucket.
At this point you may flinch because what once was a tame little fire
will have gone up a story or two! Here is our fire and bucket.
Inside the bucket, a white pillar candle.
Side note: I was very busy before this experiment and didn’t
have time to properly shop. In my haste though, I passed a Crate & Barrel
and decided to bite the bullet and buy candles there. $20 and four
candles later I felt a bit foolish. Here’s the proof:
They were pretty candles though! Oh wait, back to the science:
This fireball is an effect of expansion and phase change. The water
is denser that the wax in the bucket and therefore the wax will rise
on top of the water. The water—being put into a very hot bucket—will
instantly vaporize. This sudden violent expansion will shoot the burning
wax into the air creating an awesome fireball.
]]>
How to Build a 6-Foot-Tall Rockettag:www.madphysics.com,2005:/exp/test//1.92005-08-15T18:08:44Z2007-06-12T23:25:38ZIn 2003, I built a giant rocket for a national competition. It was just under six feet tall, had two stages, and sported an onboard electronics set. The rocket was computer-designed and made from 100% custom parts. Relive the excitement....Afrooz Familyhttp://www.madphysics.com
In 2003, I built a giant rocket for a national competition. It was just under six feet tall, had two stages, and sported an onboard electronics set. The rocket was computer-designed and made from 100% custom parts. Relive the excitement.
Introduction | Design | Construction |
Videos
Introduction
In 2003, I took part in a rocketry competition set up by the National
Association of Rocketry (NAR). The competition was to build a rocket
that met the FAA guidelines and could satisfy certain criteria:
1.
The rocket could each exactly 1500 feet (points deducted per foot missed ±).
2.
The rocket could safely transport an egg to that height.
3.
The rocket had two stages.
With these guidelines there were many designs we could go for, but
we decided to go big time. The rocket we would make would be on a rather
large scale.
We decided that the rocket would be very thin and have a large cargo
bay at the top. We decided to make a very stable rocket. That meant
that the center of gravity would have to be well above the center of
pressure.
Before we bought any parts we began designing the rocket on the computer.
We first selected all the parts and then did all the calculations.
The program helped us choose appropriate engines for our use. The final
design was almost six feet in height and just less than three and a
third pounds.
Our rocket was made out of very solid materials. The skinny part of
the body was made out of highly reinforced cardboard with a fireproof
shell. The payload, nosecone, and all adaptors were strong plastic.
The fins were fiberglass, the wadding, and safety cord were Kevlar.
Finally the chutes were nylon.
We pieced all of the parts together from our design and since we created
the whole plan we had to get all custom made parts.
We used giant G sized motors (motors run A-O the typical being B),
and to launch the second stage we used various electronics and timers.
Once everything was ready we brought the rocket out to the launch
field. Here was one of our launches:
Finally here is one of our timer tests:
]]>
Building Wilson's Cloud Chambertag:www.madphysics.com,2006:/exp/test//1.82005-06-27T21:14:10Z2007-06-12T23:26:18ZHave you ever wanted to detect ions from the comfort of your own home? Well, now you can! This lab investigates Wilson's original apparatus and suggests a model you can make at home....Afrooz Familyhttp://www.madphysics.com
Have you ever wanted to detect ions from the comfort of your own home? Well, now you can! This lab investigates Wilson's original apparatus and suggests a model you can make at home.
| Methods | Results | Methanol | Resources
A cloud chamber is used for detecting particles of ionizing radiation.
It is an airtight, super cooled, supersaturated environment. Today
we will show you how to build this device in he luxury of your own
home with simple materials.
Introduction
The Scottish Physicist Charles Wilson won the Nobel Prize in 1927
for his work developing the cloud chamber (often referred to as a Wilson
Cloud Chamber). In his chamber high energies of alpha and beta particles
enable particles to leave trails due to the many ions that were along
the path of the charged particle. These tracks have distinctive shapes.
Wilson’s chamber used water vapor and looked like this (photo
from www.njsas.org/projects/atoms/cloud_chamber/):
We will be using a different method though. Our chamber will be more
like Alexander Langsdorf’s diffusion chamber. In this chamber
dry ice cools the bottom while alcohol replaces water.
The new set-up involves an airtight transparent container. The one
we bought was from the baking section of our local grocery store. It
should be completely airtight (you should test this with water before
you put the alcohol in) and it should be completely see though. You
should then place an absorbent material on the top to hold the alcohol.
The bottom should be placed over dry ice with a metal sheet in between.
The set up should look something like this:
Here is our set up:
The best way to set the experiment up
is to place the alcohol in the chamber, seal it and put it in place.
Then after a while there should be some mist in the container. At this
point you should wait approximately 15 minutes, and then you will see
the streaks created by the ions. It should be noted that the best way
to see these is on a screen (i.e. you should put a light source in
front of your set up so it goes through your container).
Once the mist appears and you start seeing tracks you can document
these by looking at your screen. As you can see our set-up (bottom:
inlay left) produces a shadow, and within that shadow there are certain
tracks where the ions can be detected (bottom: inlay right). For more
information take a look at our resources.
This lab includes two dangerous elements. Dry is one of the dangerous
elements, it is at -78.5ºC and it is cold enough to cause bad
burns. You should know some of the dangers from our previous
lab.
Methanol is also a very very nasty chemical. For this lab you need
pure ethanol or methanol and we used over 99.8% percent methanol, which
can make you blind or kill you simply through touch or inhalation.
So make sure to use gloves and work in a ventilated area. This lab
isn’t easy, so if you don’t feel comfortable doing it,
don’t!
Finally, after killing the mood I thought we could have some fun.
After I used the methanol I needed to dispose of it, so I decided to
burn it off. So, to prove to you it was pure, look
at this video (~4mb)
and behold the pure blue flame produced. Also just in case... make
sure to have the number for your local poison control handy. You know,
just in case.
Dry Ice Explosionstag:www.madphysics.com,2005:/exp/test//1.72005-05-31T21:08:51Z2007-06-12T23:27:00ZThis lab involved a great deal of plastic shrapnel! We took dry ice (CO2 in solid form) and let it sublime in a sealed plastic bottle. This sudden change of state, and more importantly, of volume, led to the container's eventual explosion!...Afrooz Familyhttp://www.madphysics.com
This lab involved a great deal of plastic shrapnel! We took dry ice (CO2 in solid form) and let it sublime in a sealed plastic bottle. This sudden change of state, and more importantly, of volume, led to the container's eventual explosion!
Introduction | Methods | Videos
Introduction
In
this lab we took everyday dry ice that we bought from the gracery
store, and we created miniature bombs! As the solid CO2 turns into
gas, it expands tremendously. If placed in a closed space the expansion
could lead to explosion. WE don't recommend that you do this lab
as it is danegrous, and please do not use these methods to hurt anyone
or break the law. Mad Physics does not support any such behavior.
Dry
ice is simply a general term—that
is to say, not a scientific term—for carbon dioxide in its
solid form. The term comes from the solid's ability to sublime
under normal pressure. Sublimation is a process where a solid goes
directly to a gaseous state without becomimg a liquid. This lead
to the term 'dry ice' because as opposed to 'wet ice' (solid water)
one never experiences the Carbon Dioxide as a liquid. The opposite
of sublimation is deposition, an example would be the formation
of frost.
Since dry ice sublimes at 216K (-57ºC) it expands quite rapidly
at room temperature, and therefore if kept in a small container,
it can cause it to explode. We did various tests where we exploded
small plastic bottles; however, we urge you NOT to do this at
home. It is very dangerous and can lead to terrible injuries. If
you don't believe us, here is an article from the National Center
for Biotechnology Information (NCBI) and the National Library of
Medicine (NLM) talking about damage caused to the eye as a result
of this experiment done poorly:
Anyway, despite all the perils we decided to give
the lab a shot, but did use proper lab safety. We filled (platic) bottled
half way with dry ice, and then we added water. We did not seal the
bottle until we got outside and once we did... WE RAN! The bottles
expanded and eventually blew up. Although we don't recommend that you
do this lab, we have some advice for anyone so foolhardy. If the bottle
doesn't blow, don't pick it up. Just throw something at it so it does
blow up, or so the pressure gets released. Our first video shows a
bottle getting hit with a basketball:
Methanol Bottle Rocketstag:www.madphysics.com,2006:/exp/test//1.22005-05-17T01:08:46Z2006-03-10T19:34:54ZThis week we simulated the mechanics of a rocket motor running on liquid fuel. Though many rockets use composite solids, methanol is the official fuel of drag racing and remote-controlled airplane flying. Now you can see how these fire columns can launch a rocket!...Afrooz Familyhttp://www.madphysics.com
This week we simulated the mechanics of a rocket motor running on liquid fuel. Though many rockets use composite solids, methanol is the official fuel of drag racing and remote-controlled airplane flying. Now you can see how these fire columns can launch a rocket!
Methanol, the common antiseptic in rubbing alcohol, is very flammable.
This comes in handy! This lab will use methanol vapors to create a
fireball and simulate the mechanics of real rocket engines. We will
use a 5-gallon water cooler bottle to house our fireball so that the
exhaust out of the top will generate trust. This lab is a bit dangerous
so don't? partake unless you're rather foolhardy.
Methanol is very
dangerous, and therefore, should you come across it when using rubbing
alcohol is should be very diluted. The rubbing alcohol sold in most
drug stores is over 90% isopropyl alcohol; however, for the purpose
of this lab standard rubbing alcohol will do just fine.
Going back to methanol though, it has a very acute risks, they include:
Poisonous by ingestion or inhalation, may cause respiratory
failure, kidney failure, blindness. Be careful! The main reason we
want to use it though is for its flammability. Methanol is sometimes
used in internal combustion engines. Methanol is the fuel of choice
for drag racers and other open wheel racing. They use it as fuel for
remote controlled model airplanes, as well as for antifreeze, and it
can be converted into formaldehyde to create various plastics. For
an example of methanol burning click on the video to the left.
The chemical equation for the combustion of methanol is: 2CH3OH
+ 3O2 → 2CO2 + 4H20
To create the fireball we took VERY LITTLE methanol and poured it
into the container. It should be enough to barely cover the bottom
of the container (i.e. in the container its depth should be no more
than 1 cm or so). Then we should the bottle and made sure to get most
of the methanol on the sides of the bottle. At this point the bottle
is full of methanol fumes, if you want proof just smell it! Anyway
once the bottle is ready, remove the top and light it from the very
top of the lid. Do not place your hand over the bottle; you will lose
your hand! We recommend using a longer grill lighter so you are at
a safer distance. Once the top is on fire it will spread inside creating
a fireball. As the temperature soars the gas will expand tremendously.
Burning gas will shoot out of the can and you will have the force needed
to propel a rocket. This is the premise of rocketry (using liquid fuel).
Both model rockets and NASA also use solid composite fuels. Below is
a series of photographs documenting one second of time:
Next is a series of two movies documenting this process. The first
one (left) is a closer slow-motion shot of the fireball being created
and expelled and the second (right) shows from further away the length
of the fire column created by the exhaust.
The lab worked. When we filled a regular bottle with methanol the
vapors combusted to create a large fire column, which while leaving
the contained created enough thrust for it to theoretically move a
certain distance. If there were a steady stream of fuel and an ignition
system, we could have made a rocket, or could we? We found out that
fuel and ignition is not enough, just like in a car, you need something
extra. We turned to the equation again:
2CH3OH + 3O2 → 2CO2 + 4H20
We were missing oxygen! It was clearly there. When we burnt the fuel
the first time it used all of the oxygen in the container, and it never
filled back up. Therefore we had to pump the bottle with air again!
Once we did the test worked again; however, without oxygen there can
be no fire. Therefore, for there to be any possibility of creating
a rocket, along with constant fuel, we would need constant air. Maybe
next time!
Finally, here is a video of lighting an
airless container. If you
notice if catches on fire. That is not the vapor though. The methanol
left on the bottle caught fire and we actually melted one of our bottles,
oops!
]]>
Red Beet pH Metertag:www.madphysics.com,2005:/exp/test//1.62005-05-09T21:03:02Z2006-03-10T21:07:31ZIndicators are used everyday in labs to measure the pH of different substances. The universal indicator stands out among the others because of its wider scale. Today’s lab investigates the use of red beets as a pH indicator....Afrooz Familyhttp://www.madphysics.com
Indicators are used everyday in labs to measure the pH of different substances. The universal indicator stands out among the others because of its wider scale. Today’s lab investigates the use of red beets as a pH indicator.
Indicators
are used everyday in labs to measure the pH of different substances. There
are many varieties of indicators that are used depending of the relevance
of their color scales (most have limited but accurate scales); however,
the universal indicator stands out among the others because of its wider
scale. Today’s lab investigates the use of red beets as a pH indicator.
An indicator is a compound that determines pH by detecting H+ protons.
The indicator, when introduced to a substance may bond with the H+ or OH-
ions, and the different electronic configurations provide the indicator
with its final color.
In this lab we took a deep base and mixed it with our red beet indicator.
The result was a deep purple solution. To demonstrate how indicators change
color to show pH, we put dry ice in the solution. When dry ice sublimes
it will make the solution it is in more acidic; therefore, over time, the
color of our beet/base solution should change. We’ll see what happens!
One small caution: dry ice is dangerous. It is rather cold and can cause
nasty burns. Please don't touch it barehanded. If you would like
to do this lab at home (it is relatively safe) make sure to use proper
equipment when handling the ice. Insulated oven gloves work nicely.
We started our lab by putting some red beets in boiling water. It took
a little while for the water to turn deep red (as it should) so
we let it boil while we went to get some dry ice. Upon return we noticed
that the water was nice and red and we were ready to start with our experiment.
We put amounts of our indicator aside and then we prepared to mix it with
Windex. The proportions had to be decent because we had to make sure that
most of the change in color was a result of the indicator reacting with
the base, rather that the Windex just dying the solution. Play around until
you get it more or less right, and then proceed to the fun stuff!
Anyway to give you an idea of what the solution should l ook like when
the proportions are right. Take a look at the following picture:
Once we
got the mixture right we cut a small piece of dry ice and we put it into
the beaker. This part is rather messy so we would advise that you do it
over a sink. When dry ice goes into a liquid it bubbles and creates a fog.
This is something most people have witnessed; however, if you haven’t
seen it in soapy water, you’re missing half the fun. In soapy water
it bubbles and said bubbles tend to overflow and go everywhere. This is
also the case with Windex, except for the bubbles probably aren’t
great for your skin, and are probably worse for your digestive tract!
Anyway, I digress. There should be noticeable changes in color after a
few seconds. This should also be a sign that the proportions were done
more or less correctly. We took a sequence of images to show you what we
thought it should look like. The next three pictures are in chronological
order left to right:
Finally when you are all done, make sure to have a beaker full of the
original concoction and then after the mess is cleaned. Data can be collected
and conclusions can be drawn.
Finally when we examine our final results we can see that our methods
did in fact work. We started off with a purple/green mixture that meant
that we had a strong base. Then after the dry ice was added the liquid
became lighter and lighter until it stopped around orange or red. This
means that we did in fact make the transition from base to acid. The before
and after picture below is quite telling:
]]>
Fire Extinguisherstag:www.madphysics.com,2005:/exp/test//1.52005-05-02T05:36:22Z2007-06-12T23:28:30ZWe put our handy-dandy dry chemical extinguisher up against the backyard hose to see which one really did the best job. We tested with not only large wood fires, but also liquid fires using gas! Except for a couple mishaps, we were injury free. Great photos!...Afrooz Familyhttp://www.madphysics.com
We put our handy-dandy dry chemical extinguisher up against the backyard hose to see which one really did the best job. We tested with not only large wood fires, but also liquid fires using gas! Except for a couple mishaps, we were injury free. Great photos!
Intro | Test 1, 2, 3, 4 | Conclusions
Introduction
This
lab investigates fire extinguishers. There are scientific processes that
make these extinguishers more efficient than other fire suppressants such
as water. However, in understanding how these extinguishers work, we found
that these are good alternatives to extinguishers around the house. One
important thing to note is that there are different types of fires:
Type A: Wood, Paper, Etc.
Type B: Flammable Liquids
Type C: Electrical
All of them are different, and one should note that only type A fires
can be treated with water.
Also to understand these fires more we must know what fire is. It is a
chemical combustion reaction that is a result of a fuel (wood, gas, etc.)
that has reached its combustion temperature reacting with a gas like oxygen
to combust. Woods combustion temperature is 260ºC.
Our experiments tested extinguishers against water to see how they worked
for conventional purposes, but again, note that using water to put out
type B fires is very unwise. Anyway, we did four trials, and ended up with
our final results.
We created a large fire with wood on a fire resistant surface and we let
it grow until all of the wood was alight (1), we then began to spray it
with the extinguisher (2) and after two or three seconds, the whole thing
was out (3). One important effect to note is that right after the fire
was put out, there was very little smoke (4), and the wood was not hot.
The way the extinguisher dealt with this was with monoammonium phosphate
foam. This foam covers the fuel keeping it away from oxygen, while it decomposes
to create carbon dioxide, which also acts as a barrier. The foam also enables
the material to cool down. All told it acts quickly and prevents the fire
from restarting after it is out.
We created a similar fire again (2) and this time began to spray it with
water (2) from a garden hose. It took longer than the extinguisher to put
out (3) and still when the fire was out completely, there was a great deal
of smoke and steam (4) and the wood remained hot.
The results showed that water was very effective against Type A fires,
but the fact that the wood remained hot after the fire was put out showed
that the fire could easily return because if the temperature of the wood
rose, it could combust. This is often the case with large fires.
This time we created a fire with gasoline only. The fire was rather violent
at first so we would advise against doing this at home. To put it into
perspective—we, the experts (cough! cough!)—had our own accident
doing this test. Our gas can caught on fire, and the fire could have spread
had we not put it out immediately. Liquid fires are dangerous because they
can spread so make sure not to try one near any grass or vegetation. Keep
it isolated because it can get messy. Anyway, once we got the fire burning
it looked like this:
After we sprayed it with the extinguisher the fire went out very quickly
and we were left only with the extinguisher’s foam. There was not
heat and the gasoline was perfectly covered. The extinguisher proved very
effective in this case.
Water will not put out a liquid fire. It will often make the fire float
on top and it will help spread it. We found that because the extinguisher
is the best solution, if you need to put out a Type B fire and do not have
one; you could use a similar technique. If you smother a fire with a heavy
blanket or better yet Baking Soda it will go out. We would
recommend baking soda as the best alternative to an extinguisher in this
situation. It sounds crazy but it works. Anyway, to make this demo work
we decided to use very little gas and a lot of water. We displaced the
fire a bit, but put it out by smothering it with water. We would not recommend
this technique though, so stick with the baking supplies.
Electrical fires are very dangerous and hard to contain. Never use water
to fight them because you will get hurt. Water conducts electricity, and
that is why some extinguishers can only treat them. When you buy an extinguisher
for your house (which we recommend), we suggest that you make sure it covers
Types A, B, & C.
When it came to Type A fires water and extinguishers seemed pretty equal.
They took similar amounts of time, but the major point was that the extinguisher
made sure that the fire did not come back. If you are dealing with a large
fire, it is a different story though. It is hard to come across tons of
foam, so here is how the fire department deals with Type A:
They use their pumper trucks to douse the fire with water, they wait until
it is all out and then they use foam to prevent the fire from coming back.
The biggest risk is for a fire scene to catch on fire again, so most fire
trucks carry about 20 gallons of foam for this purpose.
For Type B the extinguisher won. Water should not be an option, so if
you are out of luck you should use baking soda instead!
Finally remember, only treat a fire if it is small and you know what you
are doing. We recommend that you buy an extinguisher, but we suggest that
if the fire gets out of hand, leave as safely as possible and then contact
your local fire department. They have the coolest equipment and they best
know-how to make sure that you are safe and that the fire is contained.
Also if you buy an extinguisher make sure you know how to use it, put
it in a readily available location, and check it often to make sure it
is pressurized.
]]>
Giant Hooke's Law Demonstrationtag:www.madphysics.com,2005:/exp/test//1.42005-04-25T05:30:07Z2007-06-12T23:29:19ZHooke's Law is commonly demonstrated with 100g weights and a small spring. We decided to keep the concepts but ditch the lab. In our version, the basic premise remains, but we demonstrate it with a GIANT garage-door spring and a 60 kg, 15-year-old Dutch boy!...Afrooz Familyhttp://www.madphysics.com
Hooke's Law is commonly demonstrated with 100g weights and a small spring. We decided to keep the concepts but ditch the lab. In our version, the basic premise remains, but we demonstrate it with a GIANT garage-door spring and a 60 kg, 15-year-old Dutch boy!
Hooke’s law is names after Robert Hooke, a physicist,
who in the seventeenth century published the anagram: ceiiinosssttuv. It
was later revealed that the anagram meant ut tensio sic vis (as
extension, the force). This law would govern elasticity (specifically
springs) for many years.
Hooke’s law is a fundamental concept for springs, but does not
accurately predict the behavior of other elastic objects. The law stipulates
that if a force (F) is put on a spring, its extension will be linearly
proportional to its tensile stress. The equation for a spring is:
F=-kx
Of course with springs there is a limited amount of forced that can
be applied until the spring loses its original shape. This is called
the elastic limit, and this takes us into today’s lab. Most physics
classes use very simple set-ups to demonstrate this principle. They
take small springs and tiny weights to show the linear progression
of extension. Instead, for this lab we chose a spring with a 160lb
capacity (2), and we strung it up on a balcony with metal cabling (1).
To demonstrate this lab we got one of Joost’s (many) little
brothers to pitch in. Today’s victim—coming in at a mass
of 60kg—Martijn ten Lohuis. After we set up the spring, we checked
it to strength and safety, and then took our initial measurement.
We then tested various weights and then topped it off with Martijn’s
60kg. We got on with some difficulty (2-3), but when he was on safely
it was just fine (1). He stayed on long enough for us to get some more
measurements.
As it turned out, the relationship was linear, we had some irregularities
in our measurements, but the lab was a success. We managed to create
a giant visual for the principle, and we got it to work. We recommend
that you try this lab out with lany spring you might find, but remember
that keeping your balance on a giant spring hung from a balcony might
be a skill reserved for mad physicists!
]]>
Science of Glowstickstag:www.madphysics.com,2004:/exp/test//1.32004-12-25T02:11:25Z2007-06-12T23:29:49ZNone of the light bulbs in your house are perfectly efficient. They act as resistors in your house's electrical circuit and generate light and heat. However, there ARE forms of light that emit light without any heat! To demonstrate this phenomenon, we made use of common party favors....Afrooz Familyhttp://www.madphysics.com
None of the light bulbs in your house are perfectly efficient. They act as resistors in your house's electrical circuit and generate light and heat. However, there ARE forms of light that emit light without any heat! To demonstrate this phenomenon, we made use of common party favors.
Chemiluminescence is the emission of light through
a chemical reaction. A significant property of this form of
emission is that it produces no heat. This lab will investigate the
causes of chemiluminescence and will touch upon some of its
specific characteristics.
• Light: Visible light is
simply electromagnetic radiation. What makes the radiation visible
is its wavelength—that is to say, the range of
wavelengths. For light to be visible the wavelength must be between
400nm and 700nm (nm is nanometer or 10-9 meters). The
term for any electromagnetic radiation is luminescence. Light can
be generated in various forms, some are:
Incandescence: The emission of light due to heat
(such as the light bulbs in your house which are essentially just
resistors in your home electrical circuit).
Fluorescence and phosphorescence: The emission of
light due to radiation energy (like in a TV or fluorescent light
bulb).
Laser generation: The concentrated emission of
light using stimulated emission.
All of the forms mentioned above work the same way:
outside energy excites atoms which then release particles of light
called photons. When an atom is excited the electrons go up in
energy (and energy levels), when they fall back down to their
normal spot, they release energy in the form of light photons. A
lightstick uses the same principles, but creates light through a
chemical reaction, hence chemiluminescence.
• Chemiluminescence: In
nature, an example of chemiluminescence would be the firefly, which
very efficiently creates light through a
chemical reaction. Through
industrial chemistry we have also created a similar form of
emission; however, it is still not as efficient as that of a
firefly. The most common reaction used in novelty toys like
glowsticks is that of Cyalume with hydrogen peroxide. Peroxides
give off a lot of energy in chemical reactions, and therefore would
be perfect for such a precise and efficient reaction. Cyalume is in
fact an oxalate ester (phenyl oxalate ester) which when mixed with
hydrogen peroxide forms peroxyacid ester and phenol. The peroxyacid
ester decomposes to form more phenol, and an energetic intermediate
phase. As it decomposes into two CO2 molecules, it gives
up its energy to a waiting dye molecule, which then fluoresces.
The following is a diagram that shows the reaction
of the chemicals inclusing the intermediate steps as well as the
interations with the dyes:
The equation itself is: cyalume +
H2O2 + dye → trichlorophenol +
2CO2 + dye[♦]
In the equation above the diamond [♦] represents the excited
stage during which the chemicals give off light. There are other
forms of chemiluminescnce where the excited stage is not the
ultimate one, and therefore one must specify where in the chain of
occurences light is actually produced.
This lab is very simple to do at home. Though the
chemicals are not terribly difficult to buy separately, it is much
easier to just buy a glowstick rather than the components that make
it up. Glowsticks can be bought either at a local novelty or party
store, or online. Just
google the term glowstick and you will have
multiple options.
Once you have the glowsticks (it should be in tube
form, the thicker the better… no necklaces, etc.) the
procedures are rather straightforward; however, there are still
proper safety guidelines that should be followed. Cyalume can stain
or cause harm to skin; therefore, it is important to have a clean
and safe workspace and always wear goggles and gloves. Furthermore,
this lab also has the dangers of fire and broken glass. We DO NOT
take responsibility for any injuries or damages sustained from
attempting this lab. Now that we’ve got that out of the way,
here’s the lab:
Glowsticks work by mixing Cyalume with hydrogen
peroxide to create light. However, to preserve the light during
packaging and shipping, the chemicals are not premixed.
Therefore, you must snap the cylinder when you want to activate it.
The cylinder is full of hydrogen peroxide, and there is a glass
vial full of Cyalume. When you snap the cylinder the vial shatters
and the chemicals mix. We want to keep the vial intact.
• When you get the glowstick open the top of
the tube with a box cutter. Be careful of the hydrogen peroxide and
the vial.
• Pour the peroxide into a container and let
the vial fall out. Then clean the vial and move it to another
container. Then carefully break it and keep the Cyalume in
container 2.
You now have the two ingredients for
chemiluminescence.
The next step is to mix the chemicals. You will now
be able to see them glow, but remember, from this point you only
have a few hours of glow; however, through experimentation we found
that there are a few things that affects the glow time. The
concentration of Cyalume does change the rate of glow but more so
the intensity. The main thing that changes this process is how it
is attained. With different chemicals people have been able to
create momentary burst of intense light through varied mixtures;
however, Cyalume has been patented to glow for an extended amount
of time in an efficient way. There is one way to easily regulate
the lights intensity though, heat!
In keeping with the idea of electron movement with
added and reduced energy (heat is energy) it is rather logical that
heat would boost the intensity of the glow, and cold would do the
inverse. This being said though, one can also logically infer that
cold will actually preserve the glow. Try these at home and see
what you find, or you can just peek below at our results!
The main work that could be tested on the mixture
was the change in luminosity. We put our beaker over gauze and
heated it gently, once we saw a few bubbles we stopped. In
bird’s eye view photographs there is conclusive evidence that
the hypothesis was right. In the image below it is clear that the
light is more intense with added energy.
Nonetheless, to demonstrate the point, we found a
more visual way to show it. Firstly, the shot from inside the
beaker did not seem to visually convey the difference in intensity,
and furthermore, a still image would not give you a perspective on
time frame and effect. Therefore, we mixed the two chemicals again,
put them in a syringe, and soaked a bounty paper towel. The towel
held the chemicals brilliantly, and helped with the demonstration.
We held up the towel while keeping a flame to it. We made sure that
the towel did not catch fire, and the resulting video shows the
phenomenon quite well.
A retort stand with clamp should be used to hold a ruler and rubber band. The ruler should be accurate to ± 0.5mm. Masses should be added to the band in increments of 100g. The device holding the masses in this experiment had a mass of 50g; therefore, the progression of masses went: 0g, 50g, 150g, 250g, 350g, etc. up to 1.05kg.
Ask any big time farmer about dust explosions and they’ll know
exactly what you mean. Every year, entire “empty” wheat
silos literally explode because of the stuff floating around in the
air. This explosion usually happens when a spark or flame ignites floating
grain—an example of a free radical explosion.
This lab includes two dangerous elements. Dry is one of the dangerous
elements, it is at -78.5ºC and it is cold enough to cause bad
burns. You should know some of the dangers from our 
In
this lab we took everyday dry ice that we bought from the gracery
store, and we created miniature bombs! As the solid CO2 turns into
gas, it expands tremendously. If placed in a closed space the expansion
could lead to explosion. WE don't recommend that you do this lab
as it is danegrous, and please do not use these methods to hurt anyone
or break the law. Mad Physics does not support any such behavior. 
container,
it can cause it to explode. We did various tests where we exploded
small plastic bottles; however, we urge you NOT to do this at
home. It is very dangerous and can lead to terrible injuries. If
you don't believe us, here is an article from the National Center
for Biotechnology Information (NCBI) and the National Library of
Medicine (NLM) talking about damage caused to the eye as a result
of this experiment done poorly:
]]>
Indicators
are used everyday in labs to measure the pH of different substances. There
are many varieties of indicators that are used depending of the relevance
of their color scales (most have limited but accurate scales); however,
the universal indicator stands out among the others because of its wider
scale. Today’s lab investigates the use of red beets as a pH indicator.
so
we let it boil while we went to get some dry ice. Upon return we noticed
that the water was nice and red and we were ready to start with our experiment.
We put amounts of our indicator aside and then we prepared to mix it with
Windex. The proportions had to be decent because we had to make sure that
most of the change in color was a result of the indicator reacting with
the base, rather that the Windex just dying the solution. Play around until
you get it more or less right, and then proceed to the fun stuff!
Once we
got the mixture right we cut a small piece of dry ice and we put it into
the beaker. This part is rather messy so we would advise that you do it
over a sink. When dry ice goes into a liquid it bubbles and creates a fog.
This is something most people have witnessed; however, if you haven’t
seen it in soapy water, you’re missing half the fun. In soapy water
it bubbles and said bubbles tend to overflow and go everywhere. This is
also the case with Windex, except for the bubbles probably aren’t
great for your skin, and are probably worse for your digestive tract!
]]>
This
lab investigates fire extinguishers. There are scientific processes that
make these extinguishers more efficient than other fire suppressants such
as water. However, in understanding how these extinguishers work, we found
that these are good alternatives to extinguishers around the house. One
important thing to note is that there are different types of fires: 
• Light: Visible light is
simply electromagnetic radiation. What makes the radiation visible
is its wavelength—that is to say, the range of
wavelengths. For light to be visible the wavelength must be between
400nm and 700nm (nm is nanometer or 10-9 meters). The
term for any electromagnetic radiation is luminescence. Light can
be generated in various forms, some are:
chemical reaction. Through
industrial chemistry we have also created a similar form of
emission; however, it is still not as efficient as that of a
firefly. The most common reaction used in novelty toys like
glowsticks is that of Cyalume with hydrogen peroxide. Peroxides
give off a lot of energy in chemical reactions, and therefore would
be perfect for such a precise and efficient reaction. Cyalume is in
fact an oxalate ester (phenyl oxalate ester) which when mixed with
hydrogen peroxide forms peroxyacid ester and phenol. The peroxyacid
ester decomposes to form more phenol, and an energetic intermediate
phase. As it decomposes into two CO2 molecules, it gives
up its energy to a waiting dye molecule, which then fluoresces.
shipping, the chemicals are not premixed.
Therefore, you must snap the cylinder when you want to activate it.
The cylinder is full of hydrogen peroxide, and there is a glass
vial full of Cyalume. When you snap the cylinder the vial shatters
and the chemicals mix. We want to keep the vial intact.