Section 4.3 Pg

 This often involves integrating two or more concepts.  I.e. Boyle’s and Charles’ Laws were combined to create the Combined Gas Law  Similarly, Avogadro’s Theory and the Mole concept can also be combined:  Avogadro: “Equal volumes of any gases at the same temperature and pressure contain equal numbers of entities”  Therefore, for all gases at a specific temperature and pressure, there must be a certain volume, the ___________________________, that contains one mole of entities  Molar Volume:

 Molar volume is the ______________ for all gases at the same temperature and pressure (remember, all gases have the same physical properties)  At STP, molar volume = ________________( kPa and 0°C)  At SATP, molar volume = _______________(100 kPa and 25°C)  This can be used as a conversion factor just like molar mass! At STP, one mole of gas has a volume of 22.4 L, which is approximately the volume of 11 “empty” 2 L pop bottles. STP = 22.4L/mol SATP = 24.8 L/mol

 Chemists created the concept of molar volume to convert between volume and chemical amount Molar Volume as a Conversion Factor V n litres mol Remember the conversion factor will be different at STP and SATP!

 Why are we dealing with molar volume instead of molar mass???  It’s a lot ____________________ to measure the volume of a gas than trying to measure its mass.  You would have to trap the gas in a container and measure its mass on a balance and them make corrections for the buoyant force of the surrounding air... not easy

1. Calculate the volume occupied by mol of carbon dioxide at SATP. 2. What chemical amount of oxygen is available for a combustion reaction in a volume of 5.6 L at STP? STP = 22.4L/mol SATP = 24.8 L/mol

3. What volume does 3.50 g of helium gas (He) occupy at SATP?  Once these calculations are clearly understood, they can be combined into a single calculation using unit analysis. All units except the final unit will cancel. STP = 22.4L/mol SATP = 24.8 L/mol

4. A propane tank for a barbecue contains liquefied propane. IF the tank mass drops by 9.1 kg after a month’s use, what volume of propane gas at SATP was used for cooking? Molar mass (M): C 3 H 8(g) =  What if I wanted your answer in litres? STP = 22.4L/mol SATP = 24.8 L/mol 5.1 kL x 1000L = 5100 L= 5.1 x 10 3 L 1 kL

STP = 22.4L/mol SATP = 24.8 L/mol Molar volume: the volume that one mole of a gas occupies at a specified temperature and pressure Homework: pg. 171 #5 - 12