Sometimes in lab we collect the gas formed by a chemical reaction over water. This makes it easy to isolate and measure the amount of gas produced. Suppose the H2, gas evolved by a certain chemical reaction taking place at 40.0 °C is collected over water, using an apparatus something like that in the sketch, and the final volume of gas in the collection tube is measured to be 80.0 mL. Required:
Calculate the mass of H2 that is in the collection tube.