Question

Small quantities of hydrogen gas can be prepared in the lab by addition of hydrochloric acid to zinc. The gas is typically collected over water (what does collected over water mean?). What volume of hydrogen can be collected from 0.625g Zn? The total pressure is 784torr at 30^oC. Water has a vapor pressure of 32torr at 30^oC.

Zn(s) + 2 HCl(aq) --> ZnCl₂(aq) + H₂)g)

a) 30mL b) 157mL c) 240mL d) 316mL e) 564mL