CHEM 103 module 3 problem set 6 study guide

1. A sample of hydrogen (H2) gas is collected over water at 35oC and 725 mm. The volume of the gas collected is 72.0 ml. How many moles of H2 gas has been collected? How many grams of H2 gas has been collected? Your Answer: P(H2) = 725 - P(H2O) (from table) = 725 - 42.2 = 682.8 x 1 atm / 760 mm = 0.898 atm H2 from Ideal Gas Law: n(H2) = PV / RT = (0.898 atm) (72.0 ml x 1 liter / 1000 ml) / (0.0821) (308K) n(H2) = 0.0647 / 25.2868 n(H2) = 0. moles grams(H2) = moles x MW = 0. moles x 2.016 grams / 1 mole = 0.00516 grams PH2 = 725 - P H2O (from table) = 725 - 42.2 = 682.8 x 1 atm / 760 mm = 0.898 atm H2 from Ideal Gas Law: n H2 = PV / RT = (0.898 atm) (72.0 ml x 1 liter / 1000 ml) / (0.0821) (308oK) n H2 = 0. moles grams H2 = moles x MW = 0. moles x 2.016 grams / 1 mole = 0.00515 grams Question 2 Not yet graded / 0 pts COLLECTION OF GA