Question

Write a balanced equation for each of the following neutralization reactions: (a) Lithium hydroxide solution is added to carbonic acid. (b) Calcium hydroxide solution is added to nitric acid.

Short answer

(a) 2LiOH + H2CO3 → Li2CO3 + 2H2O; (b) Ca(OH)2 + 2HNO3 → Ca(NO3)2 + 2H2O.

Step-by-step solution

Understanding the Concept

Before writing the balanced equations, it's important to understand that neutralization reactions occur when an acid and a base react to form water and a salt. Here, lithium hydroxide and calcium hydroxide are bases, and carbonic acid and nitric acid are acids.

Identifying the Reactants and Products for Reaction (a)

For the reaction between lithium hydroxide (LiOH) and carbonic acid (H2CO3), the acid provides H+ ions and the base provides OH- ions, leading to the formation of water (H2O) and the salt lithium carbonate (Li2CO3).

Balancing Reaction (a)

The unbalanced chemical equation is: LiOH + H2CO3 → Li2CO3 + H2O. To balance it, we observe that the two lithium ions are needed to form lithium carbonate, so we need two lithium hydroxide molecules: 2LiOH + H2CO3 → Li2CO3 + 2H2O.

Identifying the Reactants and Products for Reaction (b)

For the reaction between calcium hydroxide (Ca(OH)2) and nitric acid (HNO3), the acid provides H+ ions, and the base provides OH- ions, forming water (H2O) and the salt calcium nitrate (Ca(NO3)2).

Balancing Reaction (b)

The unbalanced chemical equation is: Ca(OH)2 + HNO3 → Ca(NO3)2 + H2O. To balance it, two nitric acid molecules are required to interact with one calcium hydroxide molecule: Ca(OH)2 + 2HNO3 → Ca(NO3)2 + 2H2O.

Key concepts

Balancing Chemical Equations

In chemistry, balancing chemical equations is essential to accurately represent a chemical reaction. An unbalanced equation suggests incorrect quantities of reactants and products, failing to obey the Law of Conservation of Mass. It stipulates that matter cannot be created or destroyed in a reaction.
To balance an equation:

• Start by writing the correct formulas for all reactants and products.
• Count the number of each type of atom on both sides of the equation.
• Adjust coefficients (numbers in front of molecules) to get the same number of each type of atom on both sides.
• Ensure the smallest set of whole numbers is used for coefficients.

For example, in the reaction between lithium hydroxide and carbonic acid, the equation starts as:\[\text{LiOH} + \text{H}_2\text{CO}_3 \rightarrow \text{Li}_2\text{CO}_3 + \text{H}_2\text{O}\]Counting atoms shows the imbalance in lithium, so we adjust to:\[2\text{LiOH} + \text{H}_2\text{CO}_3 \rightarrow \text{Li}_2\text{CO}_3 + 2\text{H}_2\text{O}\]Balancing ensures the reaction fully abides by the laws of chemistry.

Acid-Base Reactions

Acid-base reactions, also known as neutralization reactions, occur when an acid reacts with a base to form water and a salt. Acids are substances that increase the concentration of hydrogen ions (H\(^+\)) when dissolved in water, while bases increase hydroxide ions (OH\(^-\)).
When they react, hydrogen ions from the acid and hydroxide ions from the base combine to form water. The remaining ions form a salt, a compound composed of the cation from the base and the anion from the acid.
Let's examine reaction (a) in our exercise for better understanding:

• Lithium hydroxide (LiOH) acts as the base, providing OH\(^-\).
• Carbonic acid (H\(_2\)CO\(_3\)) acts as the acid, providing H\(^+\).
• These ions combine to form water (H\(_2\)O) and lithium carbonate (Li\(_2\)CO\(_3\) ).

In neutralization reactions such as this, the products are always water and a salt.

Chemical Reaction Types

Chemical reactions can be classified into several types based on the nature of the reactants and products. One such classification is into synthesis, decomposition, single replacement, double replacement, and combustion reactions.
Neutralization reactions, specifically, are a subset of double replacement reactions. In a double replacement reaction, ions from two compounds interchange to form new compounds.
In our examples:

• Reactants lithium hydroxide and carbonic acid form products lithium carbonate and water.
• In reaction (b) calcium hydroxide and nitric acid yield calcium nitrate and water.

These reactions involve the swapping of ions between the acid and the base. Such reactions are essential in various industrial and biological processes, including the manufacturing of fertilizers, pharmaceuticals, and in digestion.