Question

consider the reaction of calcium oxide and water:
cao + h₂o → ca(oh)₂
0.20 moles of calcium oxide and 0.40 moles of water were mixed. which of the following statements about the reaction is correct?
calcium oxide is a limiting reagent.
it is a redox reaction.
water is a limiting reagent.
0.20 g of calcium oxide and 0.40 g of water were mixed.

Explanation:

Step1: Analyze reaction stoichiometry

The balanced equation is $CaO + H_2O
ightarrow Ca(OH)_2$, which has a 1:1 mole - ratio between $CaO$ and $H_2O$.

Step2: Determine moles of reactants

We have 0.20 moles of $CaO$ and 0.40 moles of $H_2O$. Since the mole - ratio of $CaO$ to $H_2O$ is 1:1, the reactant with fewer moles will be the limiting reagent. Here, $CaO$ has fewer moles.

Step3: Check for redox nature

In the reaction, the oxidation states of $Ca$, $O$, and $H$ do not change. So, it is not a redox reaction. Also, the amounts given in the problem are in moles, not grams for the last option.

Answer:

Calcium oxide is a limiting reagent.