Question

Complete and balance the following neutralization reactions: (a) \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}(a q)+\mathrm{Sr}(\mathrm{OH})_{2}(a q) \longrightarrow\) (b) \(\mathrm{H}_{2} \mathrm{SO}_{4}(a q)+\mathrm{NH}_{4} \mathrm{OH}(a q) \longrightarrow\)

Short answer

(a) \( 2\mathrm{HC}_2\mathrm{H}_3\mathrm{O}_2 + \mathrm{Sr(OH)}_2 \rightarrow 2\mathrm{H}_2\mathrm{O} + \mathrm{Sr(C}_2\mathrm{H}_3\mathrm{O}_2)_2 \) (b) \( \mathrm{H}_2\mathrm{SO}_4 + 2\mathrm{NH}_4\mathrm{OH} \rightarrow 2\mathrm{H}_2\mathrm{O} + \mathrm{(NH}_4)_2\mathrm{SO}_4 \)

Step-by-step solution

Identify the reactants and products for equation (a)

The reactants given are acetic acid \( \mathrm{HC}_2\mathrm{H}_3\mathrm{O}_2 \) and strontium hydroxide \( \mathrm{Sr(OH)}_2 \). The products of this neutralization reaction will be water \( \mathrm{H}_2\mathrm{O} \) and the salt strontium acetate, \( \mathrm{Sr(C}_2\mathrm{H}_3\mathrm{O}_2)_2 \).

Write the unbalanced chemical equation for (a)

The unbalanced equation is:\[ \mathrm{HC}_2\mathrm{H}_3\mathrm{O}_2(aq) + \mathrm{Sr(OH)}_2(aq) \rightarrow \mathrm{H}_2\mathrm{O}(l) + \mathrm{Sr(C}_2\mathrm{H}_3\mathrm{O}_2)_2(aq) \]

Balance the chemical equation for (a)

Balance the number of each type of atom on both sides. Starting with strontium and acetate ions:- 2 acetic acid molecules needed per formula unit of strontium acetate.- Since \( \mathrm{Sr(OH)}_2 \) has 2 hydroxide ions, it will produce 2 water molecules.The balanced equation becomes:\[ 2\mathrm{HC}_2\mathrm{H}_3\mathrm{O}_2(aq) + \mathrm{Sr(OH)}_2(aq) \rightarrow 2\mathrm{H}_2\mathrm{O}(l) + \mathrm{Sr(C}_2\mathrm{H}_3\mathrm{O}_2)_2(aq) \]

Identify reactants and products for equation (b)

The reactants are sulfuric acid \( \mathrm{H}_2\mathrm{SO}_4 \) and ammonium hydroxide \( \mathrm{NH}_4\mathrm{OH} \). The products formed will be water \( \mathrm{H}_2\mathrm{O} \) and ammonium sulfate \( \mathrm{(NH}_4)_2\mathrm{SO}_4 \).

Write the unbalanced chemical equation for (b)

The unbalanced equation is:\[ \mathrm{H}_2\mathrm{SO}_4(aq) + \mathrm{NH}_4\mathrm{OH}(aq) \rightarrow \mathrm{H}_2\mathrm{O}(l) + \mathrm{(NH}_4)_2\mathrm{SO}_4(aq) \]

Balance the chemical equation for (b)

To balance, consider ammonium and hydroxide:- 2 ammonium hydroxide molecules are needed per one sulfuric acid molecule to form one ammonium sulfate.- 2 water molecules are produced.The balanced equation is:\[ \mathrm{H}_2\mathrm{SO}_4(aq) + 2\mathrm{NH}_4\mathrm{OH}(aq) \rightarrow 2\mathrm{H}_2\mathrm{O}(l) + \mathrm{(NH}_4)_2\mathrm{SO}_4(aq) \]

Key concepts

Chemical Equation Balancing

In every chemical reaction, the law of conservation of mass must be upheld. This means that the same number of each type of atom must be present on both sides of the equation.
Balancing equations ensures that this rule is followed. When balancing, begin by identifying the different atoms in the reactants and products. For instance, in the reaction involving acetic acid and strontium hydroxide, we have carbon, hydrogen, oxygen, and strontium atoms. For the reaction with sulfuric acid and ammonium hydroxide, we see hydrogen, sulfur, oxygen, and nitrogen.
An effective strategy is to start balancing with the most complex molecule or the element that appears the least. Adjust the coefficients of the molecules to ensure the number of atoms of each element is equal on both sides. In the case of acetic acid and strontium hydroxide, this meant ensuring sufficient acetic acid molecules to form the desired salt and water molecules.
For more complicated reactions, it is sometimes helpful to write out each element separately and adjust coefficients accordingly. Always recheck your work to ensure the equation is completely balanced.

Acid-Base Reactions

Acid-base reactions are a fundamental type of chemical reaction where an acid and a base interact to form a salt and water. This type of reaction can be seen in our given exercises with acetic acid neutralizing strontium hydroxide and sulfuric acid neutralizing ammonium hydroxide.
These reactions are known for producing water, as water is a product of the hydrogen ions ( H^+ ) from the acid reacting with the hydroxide ions ( OH^− ) from the base. The salt formed in these equations consists of the remaining ions from the acid and base.
A great way to identify an acid-base reaction is by recognizing the formation of water and the resulting salt. These are known as neutralization reactions because the acid ( H^+ ) and base ( OH^− ) cancel each other out, creating a neutral solution.
The balancing of these reactions, as shown in the practice problems, reflects the stoichiometry involved both in the H^+ / OH^− neutralization and in the formation of the salt.

Stoichiometry

Stoichiometry is the section of chemistry that studies the quantitative relationships between the reactants and products in a chemical reaction. This concept is vital in understanding how chemical equations are balanced and how reactions proceed in definite proportions.
Stoichiometry allows us to predict how much product will form from a given amount of reactant, as seen in both exercises provided. To practice stoichiometry, first ensure that the chemical equation is balanced. Once balanced, the coefficients tell you the mole ratios of the reactants and products involved.
For example, in the balanced equation for acetic acid and strontium hydroxide, the coefficients showed a 2:1:2:1 ratio. This tells us that two molecules of acetic acid react with one molecule of strontium hydroxide to produce two molecules of water and one formula unit of strontium acetate.
Understanding stoichiometry is essential for accurately solving problems involving the amount of substances and is widely applied in fields such as chemical engineering, pharmacology, and material science.