Question

Complete and balance each of the following neutralization reactions: (a) \(\mathrm{HNO}_{2}(a q)+\mathrm{Ba}(\mathrm{OH})_{2}(a q) \rightarrow\) (b) \(\mathrm{H}_{2} \mathrm{SO}_{3}(a q)+\mathrm{NaOH}(a q) \rightarrow\)

Short answer

(a) \\(2 \, \mathrm{HNO}_2(aq) + \mathrm{Ba(OH)}_2(aq) \rightarrow \mathrm{Ba(NO}_2)_2(aq) + 2 \, \mathrm{H}_2\mathrm{O}(l)\\); (b) \\(\mathrm{H}_2\mathrm{SO}_3(aq) + 2 \, \mathrm{NaOH}(aq) \rightarrow \mathrm{Na}_2\mathrm{SO}_3(aq) + 2 \, \mathrm{H}_2\mathrm{O}(l)\\).

Step-by-step solution

Understand Neutralization Reactions

A neutralization reaction involves an acid reacting with a base to produce water and a salt. Recognize that in the given reactions, you need to identify the acid (which donates \( ext{H}^+\)) and the base (which donates \( ext{OH}^-\)).

Identify the Acid and Base (a)

For (a), notice that \( ext{HNO}_2 \) is the acid, and \( ext{Ba(OH)}_2 \) is the base. This will produce water and the salt, barium nitrite (\( ext{Ba(NO}_2)_2\)).

Balance Reaction (a)

Write the unbalanced equation: \[\text{HNO}_2 + \text{Ba(OH)}_2 \rightarrow \text{Ba(NO}_2)_2 + \text{H}_2\text{O}\]Balance the equation by adjusting coefficients: \[2 \text{HNO}_2 + \text{Ba(OH)}_2 \rightarrow \text{Ba(NO}_2)_2 + 2 \text{H}_2\text{O}\]

Identify the Acid and Base (b)

For (b), the acid is \( ext{H}_2 ext{SO}_3\) and the base is \( ext{NaOH}\). The products will include water and sodium sulfite (\( ext{Na}_2 ext{SO}_3 \)).

Balance Reaction (b)

Write the unbalanced equation: \[\text{H}_2\text{SO}_3 + \text{NaOH} \rightarrow \text{Na}_2\text{SO}_3 + \text{H}_2\text{O}\]Balance by adding coefficients: \[\text{H}_2\text{SO}_3 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SO}_3 + 2\text{H}_2\text{O}\]

Final Check

Ensure both equations are balanced by verifying that atoms and charges are equal on both sides of the equations.

Key concepts

Balancing Chemical Equations

Balancing chemical equations is an essential skill in chemistry. In any chemical reaction, the number of atoms for each element must be equal on both sides of the equation. This ensures the conservation of mass.
To balance a chemical reaction, follow these steps:

• Start with the unbalanced equation.
• Count the number of atoms for each element on both sides.
• Add coefficients in front of compounds to balance the atoms for each element.
• Verify that the total number of atoms for each element matches on both sides of the equation.

In Example (a), you have: \[ \text{HNO}_2 + \text{Ba(OH)}_2 \rightarrow \text{Ba(NO}_2)_2 + \text{H}_2\text{O} \]Start by balancing barium atoms; you see there is one \( \text{Ba} \) on each side, so it's already balanced. Next, balance \( \text{NO}_2 \) by placing a coefficient of 2 in front of \( \text{HNO}_2 \). Then balance the hydrogen and oxygen by ensuring the number of \( \text{H}_2\text{O} \) matches on both sides.For Example (b), the process is similar. First, balance sodium by realizing that two sodium atoms are needed in the sodium sulfite, so adjust the \( \text{NaOH} \) coefficient to 2. Finally, verify that sulfur and hydroxide ions are balanced to complete the equation.

Acid-Base Reactions

Acid-base reactions are a central concept in chemistry. In these reactions, an acid reacts with a base resulting in the formation of water and a salt, known as neutralization.
An acid is a substance that donates protons, or \( \text{H}^+ \) ions, to a solution, while a base provides \( \text{OH}^- \) ions.For example:

• In Example (a), \( \text{HNO}_2 \) acts as the acid while \( \text{Ba(OH)}_2 \) is the base.
• The products are water and barium nitrite, forming when the \( \text{H}^+ \) from the acid combines with the \( \text{OH}^- \) ions from the base to produce water.

In Example (b), \( \text{H}_2\text{SO}_3 \) gives \( \text{H}^+ \) ions and reacts with \( \text{OH}^- \) from \( \text{NaOH} \) to form two molecules of water and sodium sulfite as the salt.The outcome is a balanced chemical reaction, accompanied by the release of heat in many cases, identifying neutralization as an exothermic process.

Stoichiometry

Stoichiometry is the quantitative relationship between reactants and products in a chemical reaction. Understanding stoichiometry allows chemists to predict the amounts of substances consumed and produced in a given reaction.
Key elements of stoichiometry include:

• Using balanced chemical equations to determine the mole ratio between substances.
• Using these mole ratios to calculate the quantities of missing reactants or products.

For the neutralization reactions we've discussed, stoichiometry helps us calculate the exact amount of each reactant needed to completely react with one another without any leftover.
In Example (a):

• The balanced equation \( 2 \text{HNO}_2 + \text{Ba(OH)}_2 \rightarrow \text{Ba(NO}_2)_2 + 2 \text{H}_2\text{O} \) indicates a 2:1 ratio between \( \text{HNO}_2 \) and \( \text{Ba(OH)}_2 \).

In Example (b):

• The balanced equation \( \text{H}_2\text{SO}_3 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SO}_3 + 2\text{H}_2\text{O} \) shows a 1:2 ratio between \( \text{H}_2\text{SO}_3 \) and \( \text{NaOH} \).

This ensures that all substances are utilized optimally, with the reactions driven to completion in the practical scenarios using these stoichiometric calculations.