If you start with 82.4 g of hydrochloric acid, how many liters of hydrogen gas at STP will form? Zn(s) + 2 HCl(aq) ZnCl2(aq) + H2(g)

Answer 1

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

Assuming that Zn(s) is not limiting, we can find the moles of H2 gas formed, and then knowing the conditions of STP, we can convert the moles of H2 (g) to liters of H2(g).

moles of HCl used = 82.4 g HCl x 1 mol HCl / 36.5 g = 2.26 moles HCl

moles H2 gas produced = 2.26 moles HCl x 1 mole H2 gas / 2 moles HCl = 1.13 moles H2 gas

At STP, 1 mole of any ideal gas = 22.4 liters. Thus, we can set up a proportion...

1 mole/22.4 L = 1.13 mole/x L and x = 25.3 liters