Q. 50g CaCO3 will react with ......g of 20% HCl by weight-
(i) 36.5 gm (ii)73 gm (iii)109.5 gm (iv)182.5 gm
Equation of the reaction between calcium carbonate and hydrochloric acid
2HCl (l) + CaCO3 (s) → CaCl2 (aq) + H2O (l) + CO2 (g)
The molar mass of CaCO3 is 100 g/mol. Thus the amount of 50g of CaCO3 is 0.5 mol. One mol of calcium carbonate reacts with two mol of hydrochloric acid. Thus, 0.5 mol of CaCO3 reacts with 1 mol of HCl. The molar mass of HCl is 36.5 g/mol. The mass of 1 mol HCl is 36.5 g. The concentration of HCl in the solution by weight is w(HCl) = m(HCl) / m(solution) Thus, the mass of the 20% solution of 36.5 g of HCl is m(HCl solution) = m(HCl) / w(HCl) = 36.5 g / 0.2 = 182.5 g.
Answer: (iv) 182.5 g 50g CaCO3 will react with 182.5 g of 20% HCl by weight.