AP Chemistry - Avogadro's Law of Combining Volumes STP:      22.4 L at 0oC and 1 atmosphere pressure (101.325 kPa) SATP:    24.8 L at 20oC and 100 kPa pressure 1. A sample of carbon dioxide gas has a volume of 55.0 mL at 45oC and 85.0 kPa. Determine the volume at STP and SATP. 2. What pressure will 37.18 grams of CO2 gas exert on a container at standard temperature? 3. Find the mass of 543 mL of acetylene gas, C2H2, collected at a pressure of 85.0 kPa and standard temperature. 4. What is the density of CO2 gas measured at 5oC and 200 kPa? 5. A sample of cooking gas, taken from a cylinder, was collected and its density measured at 27oC and 100 kPa. The density at those conditions was 1.768 g/L. What was the molar mass of the cooking gas? 6. At STP, how many molecules of hydrogen are in 22.4 L? 7. Given 4.80 g of O2 gas and 2.80 g of N2 gas. Calculate for each of these samples: (a)  the number of moles (b)  the number of molecules (c)  the number of atoms (d)  the volume of each at STP and SATP