zinc is mixed with Hydrochloric acid to form zinc chloride and hydrogen gas. if 7.3 grams of zinc completely reacts how much hydrogen gas will be created? if you collect the hydrogen over water at 23 degrees celcius and a barometric pressure of 770 mmHg and you recover 2.30 liters of H2 what is the percent yield? how much H2 did you recover adjusted to stp ?