How many grams of hydrogen gas will be liberated when 6g of magnesium ribbon dissolves in 500cm3 of 6M HCl?


(Mg=24, H=1, Cl=35.5)

A.

1.2 g

B.

0.7 g

C.

0.5 g

D.

0.3 g

E.

0.12 g

Correct answer is C

Mg + 2HCl → MgCl2 + H2
6 molar contains 6 Χ 36.5 gms 1000 cc

Solution i.e 6 Χ 36.5/2gms in 500 cc
= 3 Χ 36.5
24 gms of mg will react with 2 Χ 36.5 HCl to liberate 2 gm of hydrogen
∴ 6 gms will liberate 6 Χ 2/24 Χ 1 = 0.5 gm of H2