2 HCl + Zn --> ZnCl2 + H2 When you use 25 ml. of 4.0 M HCl to produce H2 gas, how many grams of zinc does it react with? What volume of H2 gas is produced at STP?

Answer 1

2HCl + Zn ==> ZnCl₂ + H₂ .. balanced equation

moles HCl = 25 ml x 1 L / 1000 ml x 4.0 mol / L = 0.10 moles HCl

moles Zn reacted = 0.10 mols HCl x 1 mol Zn / 2 mol HCl = 0.050 mols Zn

grams Zn reacted = 0.050 mols Zn x 65.4 g Zn / mol = 3.2 g Zn reacted

To find volume of H₂ gas, we will first find moles, and then use the fact that @ STP 1 mole of gas = 22.4 L

mols H₂ = 0.10 mols HCl x 1 mol H₂ / 2 mols HCl = 0.05 mols H₂

Volume H₂ = 0.05 mols H₂ x 22.4 L / mole = 1.12 L H₂