Slaked lime (Ca(OH)2) is formed from quicklime (CaO) by the addition of water: CaO(s) + H2O(ℓ) → Ca(OH)2(s). What mass of slaked lime can be produced from a mixture of 20.7 g of CaO and 11.6 g of H2O?

Question

Slaked lime (Ca(OH)2) is formed from quicklime (CaO) by the addition of water:

CaO(s) + H2O(ℓ) → Ca(OH)2(s).

What mass of slaked lime can be produced from a mixture of 20.7 g of CaO and 11.6 g of H2O?

Answer in units of g

Answer 1

From calcium oxide we get (20.7g CaO) * (1 mol CaO / 56.1g CaO) * (1 mol Ca(OH)₂ / 1 mol CaO) = 0.369 mol Ca(OH)₂.

From water we get (11.6g H₂O) * (1 mol H₂O / 18.0g H₂O) * (1 mol Ca(OH)₂ / 1 mol H₂O) = 0.644 mol Ca(OH)₂. So water is excess and CaO is the limiting reactant.

Then (0.369 mol Ca(OH)₂) * (74.1g Ca(OH)₂ / 1 mol Ca(OH)₂) = 27.3g Ca(OH)₂.