1. Avogadro’s Principal & Molar Volume LG: I can use Avogadro’s Principal to equate volume and number of entities in a gas.

2. Avogadro's Principal Avogadro determined that different gases with equal volume, pressure, and temperature must contain the same number of particles

3. Avogadro's Principal (cont.) We can explain this using kinetic-molecular theory, but this concept was not understood in Avogadro’s time

4. Sample Problem 1 A balloon with a volume of 34.5 L is filled with 3.2 mol of helium gas. To what volume will the balloon expand is another 8.0 g of helium is added? (assuming pressure and temperature remain constant)

5. Molar Volume of a Gas Under standard conditions, 1 mole of a gas (any gas) will occupy a constant volume – STP (0⁰C and 101.3 kPa) = 22.4 L – SATP (25⁰C and 100 kPa = 24.8 L STP V = 22.4 L

6. Sample Problem 2 A sample of helium at SATP has a mass of 32.0 g. What volume does this mass of gas occupy?

7. Law of Combining Volumes Avogadro’s theory explained a previous observation about combining gases Joseph Gay-Lussac had previously observed that gases react in whole-number ratios (just like the coefficients in a balanced equation) Balanced Equation: 2 H 2 + O 2  2 H 2 O Mole Ratio: 2 : 1 : 2

8. Homework Text (Avogadro’s principal): Pg. 581 # 1 – 4 Read Section 12.4 “Gas Mixtures and the law of Partial Pressures” (Pg. 592-594) – Explain what is meant by “partial pressure” using a specific example – State Dalton’s law of partial pressures and include the formula – Read sample problems 1 & 2 (on pg. 594) and complete practice problems # 1-4 that follow