calculate the mass of Ca(OH)2 in a sample if the calcium hydroxide is neutralized by 22.50mL of 0.500M HCL?

Answer 1

Ca(OH)₂ + 2HCl ==> CaCl₂ + 2H₂O .. balanced equation

How many moles of HCl were used?

22.50 ml HCl x 1 L / 1000 ml x 0.500 mol / L = 0.01125 moles HCl used

From the mole ratio in the balanced equation, we can determine moles Ca(OH)₂ present:

0.01125 mols HCl x 1 mole Ca(OH)₂ / 2 mols HCl = 0.005625 moles Ca(OH)₂ present

Using the molar mass of Ca(OH)₂, we can finally calculate mass of Ca(OH)₂ present:

0.005625 moles Ca(OH)₂ x 74.09 g / mole = 0.417 g Ca(OH)₂ in the sample (to 3 sig.figs.)