A 8.07g sample of impure Ag2O decomposes into solid silver and O2(g). If 395mL of O2(g) is collected over water at 25 degrees Celsius and 749.2 mmHg barometric pressure, then what is the percent by mass of Ag2O in the sample? The vapor pressure of water at 25 degrees Celsius is 23.8 mmHg. What is the volume of the gas collected?

Answer 1

first, find the moles of O2 (n=PV/RT)
then, in the compound Ag2O, that is one half the moles of O , so the moles of Ag2O is 1/2 n above. convert that number of moles of silveroxide to grams, then
percent= mass/8.07