How many grams of hydrochloric acid are required to react completely with 61.8 grams of calcium hydroxide according to the following unbalanced chemical equation? HCl + Ca(OH)2 → CaCl2 + H2O

Answer 1

First, balancing the chemical equation gives us 2HCl + Ca(OH)₂ -> CaCl₂ + 2H₂O

Next, find the moles of reactant using the molar mass of calcium hydroxide.

(61.8 g Ca(OH)₂) / (74.093 g/mol) = 0.8341 mol Ca(OH)₂

Next, use the mole ratio given by the balanced chemical reaction to find moles of HCl

0.8341 mol Ca(OH)₂ x 2 mol HCl / 1 mol Ca(OH)₂ = 1.668 mol HCl

Finally, use the molar mass of HCl to find the grams of HCl needed.

1.668 mol HCl x 36.458 g/mol = 60.8 g HCl

Keep in mind, we use 3 significant figures because we were given 3 significant figures in the question.