passwella.
Menu

JAMB Chemistry 1980 Question 10

Question 10

Mole Concept and Stoichiometry

How many grams of hydrogen gas will be liberated when 6 g of magnesium ribbon dissolves in 500 cm3 of 6 M HCl? (Mg = 24, H = 1, Cl = 35.5).

  1. A.1.2 g
  2. B.0.7 g
  3. C.0.5 g
  4. D.0.3 g
  5. E.0.12 g
Show the answer and explanation

Answer: C (0.5 g)

Explanation

Mg + 2HCl → MgCl2 + H2. 6 g Mg = 0.25 mol (the acid, 3 mol, is in excess), giving 0.25 mol H2 = 0.5 g.