Answered

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?

A95 g
B180
C280

d.380

Verified Answer :

scme1702

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.

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