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Thursday, January 28, 2016

The One With More Demos Than An Aspiring Young Artist

Unit 2.A: Gas Properties

It's hard to find decent chemistry jokes because all the good ones argon.

Practice Problems:

     The first half of practice problems were pretty sneaky in my opinion. While I understood the answers and the basic concepts needed to correctly answer them, I know that if I saw these questions on a test I would immediately overthink them.  (Side Note: This fact that seemingly complex problems can be solved with such simple laws and logic something that I find great about chemistry. Was this an irrelevant detail? Maybe.) The second half of practice problems was considerably easier since they involved plugging in numbers into formulas. 
Ex. of Understood Problems
How many moles of gas are contained in 890.0 mL at 21.0 °C and 750.0 mm Hg pressure?
Answer: 0.037 moles
Ex. of Challenging Problems

While the logic behind this problem is relatively simple, the sheer amount of words in the problem is enough to throw anyone off.
     On the first day of the cycle, we were introduced to gases by having some of our classmates inhale helium and observing how their voices changed. After, Mr. Musallam inhaled a gas as well. Instead of helium, however, he inhaled sulfur hexafluoride which had the opposite effect that helium had.

feat. a pretty good Darth Vader impression

   The second day of the cycle involved several different demos that all led us to derive most of the ideal gas law equation. The first of these demos involved inflating up a balloon. The next demo involved putting a tablet of alka seltzer into a film canister with water. A soda can was crushed in the third demo. The following demo involved Mr. Musallam filling up a container with liquid with a candle. We flipped a cup upside down and got a sheet of cards tock (or paper, I'm not entirely sure) to stick to the cup for the fifth demo. The final demo involved an airzooka assault. 

The alka seltzer tablet was placed in a film canister filled halfway with water.

A can containing water is heated so that it becomes filled with water vapor, then it is placed in a tub of ice water. 

A candle is lit in a shallow dish filled with water, then covered with a glass container. 

A cup filled with water is covered with some card stock then flipped.

    After all the demos, we conducted a final lab that allowed us to verify the ideal gas law equation. It involved finding the amount of hydrogen gas in a graduated cylinder. After this lab, we discovered "R", or the gas constant that completed the ideal gas law equation.

The entire process took over NINE MINUTES!

    Below is a collection of more labs we did throughout this cycle.

Our calculations and procedure for a lab where we found the molar mass of a certain amount of butane gas.
A time lapse of the aforementioned lab, butane fills a graduated cylinder

A balloon gets blown up.

A bottle gets blown up (a lot of exploding took place in this unit).

     Most of the quiz involved plugging in numbers into a formula, just like the practice problems, but the final problem on the first page required more critical thinking. Once I realized that pressure in the problem referred to how much the particles of gas pushed on its container, I finally understood what the problem was asking. The lab portion of the quiz was similar to the second half of the practice problems as well. 

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