Question

A 6.89 gram sample of CaO is reacted with 13.79 grams of H2O. How many grams of water non limiting reactant remain after completion of the reaction. answer to two decimal places

Answer 1

11.58 g

Step-by-step explanation:

• CaO + H₂O→ Ca(OH)₂

First we convert the given masses of both reactants into moles, using their respective molar masses:

• 6.89 g CaO ÷ 56 g/mol = 0.123 mol CaO

• 13.79 g H₂O ÷ 18 g/mol = 0.766 mol H₂O

As 1 H₂O mol reacts completely with 1 CaO mol, and there are more H₂O moles than CaO moles, water is the non limiting reactant.

We calculate the mass of the reacting moles of water (the same number of CaO moles, 0.123):

• 0.123 mol H₂O * 18 g/mol = 2.21 g

Finally we calculate how many grams of water remained after the reaction:

• 13.79 g - 2.21 g = 11.58 g