Today's Guest Visitor

Today, in class, we had a great presentation by David Webb, a member of the American Vacuum Society. Wow, I had no idea such a society existed dedicated to researching the laws of physics, especially vacuums, where there is no sound. We performed a variety of experiments to further instigate our knowledge of vacuums. The first experiment we did is to figure out how much atmospheric pressure is applied to us at all times. Apparently, atmospheric pressure (at sea level) is 14.7 PSI. Whoo hoo. We held a heavy metal bar called the "Earth Bar" to show just how much pressure is being applied to us at all times.

We also used a pressure machine. Basically, it sucked all of the atmospheric air out of a canister. When you put a tied balloon in there, it got bigger. The same thing happened with marshmellows (but after withdrawing the marshmellows, they became shriveled up). Another interesting experiment proved that lack of air, or a vacuum, did not carry sounds. We put a dinging doorbell into the pressure machine, sucked out the air, and voila - the ringing stopped!

By the way, I found this column on vacuums quite interesting. I'm assuming you would probably feel the same. I also learned that something sticks to something, for example a suction cup on a shower glass door, works because of the atmospheric pressure pressing against the cup and creating a vacuum. The force of a vacuum is really strong. When you suck the air of something, it becomes very hard to open it.

Fun Fact: Toricelli, inventor of the mercury barometer, was one of the first inventors who sustained a vacuum.


The machine used looked something like pictured above, just simpler.

Gases and Back from Japantown!

On Monday, we started a new unit about gases. Gas molecules are always moving around; their molecules are the most spaced out apart (compared to liquid and solid). They have "kinetic" energy that goes up when temperature and speed go up. Gas pressure can be measured in a variety of units - mm/Hg, in/Hg, Torr, kPa, and atm. Gases are determined by pressure, volume, temperature, and number of particles. The combination gas law is P1V1 / T1 = P2V2 / T2.
It is a combination of Boyle's Law, Gay-Lussac's law, and Charles's Law.


Near absolute zero, a gas acts as a solid. Absolute zero for gases is 0 K or -273 degrees Celsius. However, temperatures for gases should be measured in Kelvin. There are also a variety of formulas to calculate the volume, pressure, or temperature of a gas. The following formulas, include ideal gas law, kinetic energy laws, and more.


Contrary to popular belief, there is no air in balloons that float. Instead, there is helium.


Ah, it feels so weird to be back from school after a long day of doing nothing...aka going to Japantown with my best friends from Japanese class. Yay! At Japantown, we went on a scavenger hunt about Japanese culture with an assigned group (Emily, Kristel, Elaiza, Rochelle, KT, Charles, and Bruce) Afterwards, we ate at Sapporo Ya. I had chicken teriyaki and ramen and tempura. And coke. MMMMM, yum. Most of my group were freshmen, who were eager to learn about Japanese culture and speak better 日本語。Nooo, I don't want to learn. xD LOL, some people ditched 7th I think. I'm not that bad. I'm eager to learn about chemistry!

MC Delta T

That's calorimetry dogg.
Calorimetry is the measurement of specific heat capacity.
Specific Heat Capacity is the amount of energy required to raise the temperature of 1 gram of a substance by 1 degrees celsius.
The specific heat capacity of water is 1 calorie per grams degree celsius.
and 1 cal is equivalent to 4.184 Joules.
Temperature and heat flow can be understood as the movement of molecules.

Whew, that was confusing.
By the way, calories are different from Calories. 1 Calorie is 1000 calories (cal).


These are some calorimetry problems (with their solutions) that we worked on.

Hmm, what else...?
During phase changes, energy is not required.
See how the line is straight in the following graph?