Answer :
The percentage of Calcium carbonate in chalk = 100%
Further explanation
Given
1.51 g piece of chalk produces 0.665 g of carbon dioxide
Required
percentage of calcium carbonate
Solution
Reaction
CaCO3 (s) + 2 HCl (aq) → CaCl2 (aq) + H2O (l) + CO2 (g)
mol CO2 :
= 0.665 g : 44 g/mol
= 0.015
From the equation, mol CaCO3 = mol CO2 = 0.015
mass CaCO3 :
= mol x MW
= 0.015 x 100
= 1.5 g