Question

Calcium oxide reacts with water in a combination reaction to produce calcium hydroxide:



CaO (s) + H2O (l) → Ca(OH)2 (s)



A 3.50-g sample of CaO is reacted with 3.38 g of H2O. How many grams of water remain after completion of reaction?

Answer 1

n(CaO) = ${\frac {3.50} {56}}=0.0625$ mol

for reaction with this amount of CaO the same amount of H₂O needed

n(H₂O) reacted = 0.0625 mol

m(H₂O) reacted = 0.0625*18 = 1.125 g

m(H₂O) remained = 3.38 - 1.125 = 2.255 g