Mr. Bouyer

Other Gas Calculations

More About Gas Laws link to an Internet Website

Avogadro's principle:

At equal temperature and pressure, equal volumes
of gases contain the same number of molecules.

 

Use this webtest link to an Internet Websiteto practice Avogadro's Law calculations.

 

Molar volume:

At STP, 22.4 dm3 of any gas contains one mole of molecules.

 

Ideal Gas: - An ideal gas is a theoretical gas that has mass, but no volume. Although this gas does not actually exist, the volume of a real gas molecules is so small that it does not greatly change calculations.             the key points to useful information on this page Lab #2

Ideal gas equation: PV = nRT

P - Standard pressure (kPa)
V - Molar volume
n - Number of moles
R - 8.31 dm3 . kPa / mole . K
T - Standard temperature (K)

 

Ideal gas equation modification

substituting for n (number of moles):

Sample problems using the ideal gas equation:

1. How many moles of gas are found in a 500 dm3 container if the conditions inside the container are 25 oC and 200 kPa?

2. What volume will 50 grams of chlorine gas occupy at STP?

3. What is the molecular weight of a gas if 150 grams of the gas occupy 250 dm3 at 500 mm Hg and 30 oC?   (this problem requires the ideal gas equation modification)

You should remember - the formula mass of a substance in grams is equal to one mole.
Therefore, the units "g/mole" represent the molecular weight, 23u.

 

Use this Java applet link to an Internet Websiteto perform experiments with an ideal gas.

 

Use this webtest link to an Internet Website to practice Ideal Gas Equation calculations.

 

Graham's Law:  (chem lab 234)

The relative rates at which two gases diffuse under identical conditions
vary inversely as the squareroots of their molecular masses.

Test Your Concept Understanding:

  1. At STP, how many molecules are found in 100 cm3 of gas?

  2. Work the following ideal gas equation practice problems:
    1. What pressure is exerted by 3 moles of a gas in a 1.5 dm3 container at 20 degrees C?
    2. At what Celsius temperature is a gas if 4.25 moles of it occupy 100 dm3 at a pressure of 96.5 kPa?
    3. What is the volume of 0.5 moles of a gas at 2 atmospheres of pressure and 15 degrees C?
    4. Oxygen at 22 oC is pumped into a 500 dm3 tank to a pressure of 2000 kPa. How many molecules of oxygen are pumped into the tank?

  3. Work the following Graham's Law practice problems:
    1. Compare the relative rate of diffusion of gaseous HCl and NH3.
    2. What is the molecular mass of a gas that diffuses half as fast as oxygen gas?
    3. If equal amounts of helium and argon are allowed to escape their open containers, which gas will be completely gone first and how much faster did it excape?

 

Use this webtest link to an Internet Websiteto practice calculations using all the gas laws.

 

Research Links:

Gas Laws Page