You have 4.271 x 102 mL of oxygen gas (O2) at 7.656 x 102 mm of Hg and 78 oC. What is the mass of the sample in milligrams?
When alcohol evaporates according to the equationC2H5OH(l) --> C2H5OH(g), how many liters of gaseous alcohol, measured at STP, are created by the evaporation of 566.1 grams of alcohol?
Use PV = nRT and solve for n = number of mols O2. Then n = grams/molar mass. You know n and molar mass, solve for grams.
mols alcohol = n = grams/molar mass
Then PV = nRT and solve for V in liters.