Lessons 8-10

Lesson 8

We learned that sublimation is to change from a solid to a gas and that is the case for dry ice. We did a lab where we placed dry ice into an airtight bag and then measured the density of the bag once the dry ice had sublimed. Fog seen around dry ice is actually tiny water droplets.

Evaporation: Phase change from a liquid to a gas.

%error= experimental value - accepted value/ accepted value *100

Gas molecules are about 1000x more dispersed than those of a solid.

 Practice Problems
1. A solid is more dense than a gas because the molecules of a solid are packed closer together.
3. Sublimation is where a solid changes to a gas and evaporation is when a liquid turns to a gas.

Lesson 9

Pressure: Force applied over a certain area. Force per unit area. Gas pressure is caused by gas molecules striking objects or the walls of a container.

Mixtures of all gases that surround you at all times is called the atmosphere.

Atmospheric pressure: Air pressure that's always present on Earth as a result of air molecules hitting surfaces of objects on earth. At sea level and 25C there is 14.7lb/in2 of air pressure from the air around us. This is 1 atm.

Practice Problems
2. Air pressure is when gas molecules hit other things.



Lesson 10

When volume of a gas decreases the pressure increases.

Inverse proportion: 2 variables are inversely proportional to each other if one variable increases as the other decreases.

PV=k or P=k/V Boyle's Law, the relationship between pressure and volume.

Boyle's Law: The pressure of a given amount of gas is inversely proportional to its volume if the temperature and amount of gas are not changed. The equation is above.

Practice Problems
5. Between gas pressure and temperature it is inversely proportional. The relationship between gas pressure and volume is directly proportional.

Posted with Blogsy