Calcium oxide reacts with water in a combination reaction to produce calcium hydroxide: CaO(s) + H₂O(l) → Ca(OH) ₂(s)
In a particular experiment,a 2.50-g sample of CaO is reacted with excess water and 2.80 g of Ca(OH) ₂ is recovered.What is the percent yield in this experiment?

Question

Quizplus · Accepted Answer

The balanced equation for the reaction is:
CaO + H2O → Ca(OH)2

The molar mass of CaO is 56.08 g/mol.
The number of moles of CaO used in the experiment is:
2.50 g / 56.08 g/mol = 0.0446 mol

According to the equation, 1 mole of CaO reacts to give 1 mole of Ca(OH)2.
Therefore, 0.0446 mol of CaO would react to give 0.0446 mol of Ca(OH)2.

The molar mass of Ca(OH)2 is 74.10 g/mol.
The theoretical yield of Ca(OH)2 is:
0.0446 mol × 74.10 g/mol = 3.30 g

The actual yield is 2.80 g.

The percent yield is calculated as:
(actual yield / theoretical yield) × 100%
= (2.80 g / 3.30 g) × 100%
= 84.9%

Therefore, the answer is D, 84.9.

Calcium Oxide Reacts with Water in a Combination Reaction to Produce