Hydrogen gas is produced when zinc reacts with hydrochloric acid. If the actual yield of this reaction is 85%?

how many grams of zinc are needed to produce 112 l of H2 at STP?

a. 95 g

b. 180

c. 280

d. 380

Reaction equation:

Zn + 2HCl → ZnCl₂ + H₂

One mole of gas occupies 22.4 L at STP

Moles of H₂ = 112/22.4

= 5 moles

The theoretical amount of Zn needed is 5 mol

The actual amount = 5/0.85

= 5.88 moles

mass = moles x Mr

mass = 5.88 x 65

mass = 382.2 g

The answer is D.