Question

Mg + 2HCl → MgCl2 + H2
How many grams of Mg is needed to produce 100 g of H2?

Answer 1

H2

n=m÷Mr

n=100×2

n=200 moles

Mole ratio

Mg : H2

1 : 1

x : 200

cross multiply= x=200

Mg

make m the subject

m=n×Mr

m=200×24.305

m=4861 g