Skip to main content
Ch.22 - Chemistry of the Nonmetals
Chapter 22, Problem 81

Complete the exercises below. Write a balanced equation for the reaction of the following compound with water: Na₂O₂ (s).

Verified step by step guidance
1
Step 1: Identify the reactants and products. The reactant is sodium peroxide (Na₂O₂) and it reacts with water (H₂O). The products of this reaction are sodium hydroxide (NaOH) and oxygen gas (O₂).
Step 2: Write the unbalanced chemical equation for the reaction: Na₂O₂ (s) + H₂O (l) → NaOH (aq) + O₂ (g).
Step 3: Balance the sodium (Na) atoms. There are 2 sodium atoms in Na₂O₂, so you need 2 NaOH molecules on the product side: Na₂O₂ (s) + H₂O (l) → 2 NaOH (aq) + O₂ (g).
Step 4: Balance the oxygen (O) atoms. There are 2 oxygen atoms in Na₂O₂ and 1 in H₂O, making a total of 3 oxygen atoms on the reactant side. On the product side, there are 2 oxygen atoms in 2 NaOH and 2 in O₂, making a total of 4. Adjust the water to balance: Na₂O₂ (s) + 2 H₂O (l) → 2 NaOH (aq) + O₂ (g).
Step 5: Balance the hydrogen (H) atoms. There are 4 hydrogen atoms on the reactant side (from 2 H₂O), and there are 4 hydrogen atoms on the product side (from 2 NaOH). The equation is now balanced.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Balanced Chemical Equations

A balanced chemical equation represents a chemical reaction where the number of atoms for each element is the same on both sides of the equation. This is crucial for obeying the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction. Balancing involves adjusting coefficients to ensure that the total number of each type of atom is equal before and after the reaction.
Recommended video:
Guided course
01:32
Balancing Chemical Equations

Hydrolysis Reactions

Hydrolysis reactions involve the reaction of a compound with water, leading to the breakdown of that compound. In the case of sodium peroxide (Na₂O₂), hydrolysis results in the formation of sodium hydroxide (NaOH) and hydrogen peroxide (H₂O₂). Understanding hydrolysis is essential for predicting the products of reactions involving ionic compounds and water.
Recommended video:
Guided course
01:30
Alcohol Reactions: Dehydration Reactions

Ionic Compounds and Solubility

Ionic compounds, such as sodium peroxide, consist of positively and negatively charged ions held together by ionic bonds. When these compounds react with water, they often dissociate into their constituent ions, which can then participate in further reactions. Knowledge of solubility rules helps determine whether a compound will dissolve in water and how it will behave in aqueous solutions.
Recommended video:
Guided course
02:11
Ionic Compounds Naming