Green Flame Reaction

I performed a favorite demonstration for my students recently where a white powder (boric acid) is mixed with small amount of methanol in a flask and then ignited, the result is an eerie green flame.   This year, however, I experimented with the time I let for the reaction to take place.  The results were noticeable.

Video 1 shows the first trial where boric acid and methanol were mixed for approximately 45 seconds before it was ignited.  The green flame lasted approximately 1 second the flame is much more green in person).

Video 2 shows the second trial where the mixture was shaken for approximately 74 seconds and then ignited.  The green flame in this trial lasted approximately 3 seconds.

I varied the reaction times for two other classes and obtained similar results.  So there you have it, vigorously shaking the mixture for longer times leads to a longer burning time for the green boric acid ester.

Boric acid has a wide range of uses other than serving as neat demos for chem teachers such as rat poison, antiseptics, acne prevention, and others.  Boric acid trimethylester (trimethyl borate) is used as a solvent for the production of waxes and varnish and such.

For those interested, the reaction is as follows:

 H3BO3 + 3CH3OH => B(H3CO)3 + 3H2O

This demonstration was modified from Bangs, Flashes, and Explosions – Illustrated Guide to Chemistry Demonstrations. ©2005 Chris Schrempp and ExploScience.com.

Afternoon Horseshoe Crab Tagging!

My family and I spent the afternoon, more like a half-hour due to thunder, tagging horseshoe crabs at Sherwood State Park in Westport, CT.  We met in the parking lot for the Park Nature Center with members of Sacred Heart University's Project Limulus who gave a brief introduction and provided instruction.  Project Limulus is a horseshoe crab research project that relies on collecting raw field data such as appearance and size.  Our group did manage to collect and tag some crabs before the thunder.

Horseshoe crabs have been around for well over 300 million years which means they were around when trilobites still roamed the oceans and somehow made through the mass extinctions at the end of the Permian (252 mya) and the more famous but less deadly Cretaceous (65 mya).  They have green blood as they use hemocyanin which is copper-based to carry oxygen rather than hemoglobin which is iron-based like most other animals on Earth.  Another interesting tidbit about horseshoe crab blood is that it contains special cells (ameoboctes) which attach to bacteria and prevent it from entering the body.  Anyway, the activity was both fun and educational.  Thanks Project Limulus.

Thermite vs. a Hamburger

The thermite reaction releases 852 kilojoules (kJ) of energy whereas a hamburger typically has only 600 Calories (Big Mac has ~600 Calories).  Looks like thermite wins!  Good  news for summer grilling.  Either way I am having a burger tonight!

However, a calorie is defined as the amount of energy need to raise the temperature of 1 gram of water 1 degree Celsius.  In the food business, for some reason, they use Calories, notice the capital 'C', therefore 1 Calorie = 1 kilocalories = 1000 calories.  Are we in the clear yet since it is 852 kJ vs. 600  Calories?  Not really as 1 calorie = 4.2 Joules or 1 Cal = 4.2 kJ which means the 600 Cal must by multiplied by 4.2 in order to convert this to kJ.  When we do this the the 600 Cal is equivalent to 2520 kJ.

The thermite reaction is shown below.  It is a reaction between powdered aluminum and iron powdered iron III oxide (rust).  To get the reaction to occur it must be heated to around 2200 degrees Celsius which is why an ignition reaction must first be used.  I used a mixture of potassium chlorate and sucrose plus a few drops of sulfuric acid.

Video 1) Thermite Ignitor (KClO3 + Sucrose + Sulfuric Acid)

Video 2) Thermite

The good thing about having the AP Chem Test first is it leaves more time at the end of the year to perform neat demos.

What you can do with a nitrile glove and a pressure chamber:

Having fun with the gas laws.  The air inside the gloves expand as the air is evacuated from surroundings!  This is an example of Boyle's Law where the volume of the glove expands as pressure in the chamber is decreased as temperature is held constant.

For Edline Users!  

It is possible to insert graphs, pictures, or diagrams into Edline quizzes.  Shown below is a partial quiz I created on Edline where questions 14 - 16 require a phase diagram (PD water.dox).  The phase diagram pops up for the students to use for the questions.

To insert the file in a quiz or assignment, 1) create the quiz using the Quiz Builder.  2) Next click the at position where you want insert the file and 3) select Hand-Out (file attachment handed out by you).  Save your work normally and your done.

Thanks goes to Mike Sirowich (Physics Teacher) for explaining this to me, although Mike Oberdick, Tech Integration Specialist at our school probably has this on his blog (Tech Messages)!

The Blog of Phyz: How much would you pay... for the Universe?

Good post to go along with the 'Super Moon' weekend.  Although there was none to be had in the Northeast.

The Blog of Phyz: How much would you pay... for the Universe?: Neil deGrasse Tyson asks a fair question. If you were sentient in the 1960s, you'll want to wipe your tears so they won't drip onto your...

Today Seymour High School welcomed the ASA High School Tour, in partnership with the Campaign for Tobacco-Free Kids and the U.S. Marine Corps, which brings the world’s best BMX riders to high schools across America show it's cool to be smoke free.

Although it was raining the show went on anyway, in the Gymnasium of course.  It was well done and Mike Sirowich, the physics teacher, was there with his ruler and stopwatch calculating velocity and maximum height measurements.  His students will have to calculate such things next class.