2/18.10

Today in class we went over Tuesday nights homework and took notes. Also, there is a quiz tomorrow on Chapter 10 the section is unknown so know all of them. For those that qualify: The make up test will be on the 24th after school.

Tuesday night's homework answers.

19. a. 2264 J/g

b. 333.5 J/g

20. 84.3 J/g

21. a. 0.277 mol

b. 15.5 kJ/mol

22. a. 21.8 mol

b. 15.5 kJ/mol

NOTES

Charles Law (cont)

Charles Law: Volume-Temperature between volume and temperature was discovered by the French scientist Jacques Charles in 1787.

Charles found that the volume changes by 1/273 of the original volume for each Celsius degree, at a constant pressure and at an initial temperature of 0 degrees C.

The temperature 273 is absolute zero and is given a value of zero in the Kelvin temperature scale. The relationship between the two temperature scales is K=273.15 +degrees C.

Charles Law states that the volume of a fixed mass of gas at a constant pressure varies directly with the Kelvin temperature.

Gas volume and Kelvin temperature are directly proportional to each other at constant pressure.

Mathematically, Charles Law can be expressed as: V=KT or V/T=K where V is the volume, T is the Kelvin temperature, and K is a constant. the ratio V/T for any set of volume temperature values always equals the same K.

The equation reflects the fact that volume and temperature are directly proportional to each other at constant pressure.

The form of Charles Law that can be applied directly to most volume- temperature gas problems is: V1/T1 = V2/T2.

V1 and T1 represent initial conditions, and V2 and T2 represent another set of conditions.

Given three of the four values, V1, T1, V2, and T2, you can use this equation to calculate the 4th value for a system at constant pressure.

Gay-Lussacs Law: Pressure Temperature Relationship

At a constant volume, the pressure of a gas increases with increasing temperature.

Gas pressure is the result of collisions of molecules with container walls.

The energyu and frequency of collisions depend on the average kinetic energy of the molecues.

Pressure is directly proportional to Kelvin temperature.

Gay Lussacs Law: The pressure of a fixed mass of gas at constant volume varies directly with the Kelvin temperature.

This law is named after Joseph Gay-Lussac, who discovered it in 1802.

Mathematically, Gay Lussacs Law can be expressed as P=KT or P/T=K where P is pressure, T is the Kelvin temperaure, and K is a constant. The ratio P/T for any set of volume-temperature values always equals the same K.