1. Chapter 11: Molecular Composition of Gases

2. Sect. 11-1: Volume-Mass Relationships of Gases Gay-Lussac’s Law of combining volumes of gases – at constant temperature and pressure, the volume of gaseous reactants and products can be expressed as ratios of small whole numbers

3. Avogadro’s law – equal volumes of gases at the same temperature and pressure contain equal number of molecules Coefficients in a balanced equation show relative # of molecules, moles, and volumes

4. Standard molar volume of a gas – the volume occupied by one mole of a gas at STP  Numerically 22.4 L = 1 mol

5. Ex: A chemical reaction produces 0.0680 mol of oxygen gas. What volume in liters is occupied by this gas sample at STP?

6. Ex.: A chemical reaction produced 98.0 mL of sulfur dioxide gas at STP. What was the mass (in grams) of the gas produced?

7. Sect. 11-2: The Ideal Gas Law Ideal gas law – mathematical relationship between pressure, volume, temperature, and number of moles of gas  Relationships are the same as in other gas laws

8. PV = nRT Ideal gas constant – the constant, R, in the ideal gas law  Pg. 342 in textbook  Value depends upon pressure units

9. Ex: What is the volume, in liters, of 0.250 mol of oxygen gas at 20.0°C and.974 atm pressure?

10. What mass of chlorine gas, Cl 2, in grams, is contained in a 10.0 L tank at 27°C and 3.50 atm of pressure?

11. Ideal gas law can be rearranged to accommodate mass or density  M = mRT/PV, where M is molar mass and m is mass of sample  D = MP/RT, where M is molar mass and D is density

12. At 28°C and 0.974 atm, 1.00 L of gas has a mass of 5.16 g. What is the molar mass of this gas?

13. Sect. 11-4: Effusion and Diffusion Diffusion – gradual, random mixing of gas particles Effusion – gas particles escaping from a tiny opening in their container

14. Graham’s Law of Effusion – the rates of effusion of gases at the same temperature and pressure are inversely proportional to the square roots of their molar masses Rate of A = √Molar Mass B Rate of B √Molar Mass A

15. Ex: A sample of hydrogen gas effuses about 9 times faster than an unknown gas. What is the molar mass of the unknown gas?