Question

Write a neutralization reaction for each acid and base pair. (a) \(\mathrm{HI}(a q)\) and \(\mathrm{NaOH}(a q)\) (b) \(\mathrm{HBr}(a q)\) and \(\mathrm{KOH}(a q)\) (c) \(\mathrm{HNO}_{3}(a q)\) and \(\mathrm{Ba}(\mathrm{OH})_{2}(a q)\) (d) \(\mathrm{HClO}_{4}(a q)\) and \(\mathrm{Sr}(\mathrm{OH})_{2}(a q)\)

Short answer

The neutralization reactions are (a) \(\mathrm{HI} + \mathrm{NaOH} \rightarrow \mathrm{NaI} + \mathrm{H_2O}\)\, (b) \(\mathrm{HBr} + \mathrm{KOH} \rightarrow \mathrm{KBr} + \mathrm{H_2O}\)\, (c) \(\mathrm{HNO_3} + \mathrm{Ba(OH)_2} \rightarrow \mathrm{Ba(NO_3)_2} + 2\mathrm{H_2O}\)\, and (d) \(\mathrm{HClO_4} + \mathrm{Sr(OH)_2} \rightarrow \mathrm{Sr(ClO_4)_2} + 2\mathrm{H_2O}\).

Step-by-step solution

Identifying the Acid and Base Pairs

Firstly, identify the acid and the base in each pair. Acids typically start with an H and bases typically contain OH.

Writing the Neutralization Reaction

Write a chemical equation for each acid-base pair. In each reaction, the hydrogen ion (H+) from the acid combines with the hydroxide ion (OH-) from the base to form water (H2O). The remaining species form a salt.

Balancing the Chemical Equations

Ensure that the number of atoms of each element is equal on both sides of the equation. This may require multiplying the formulas by appropriate coefficients.

Neutralization Reaction for Pair (a)

The reaction for the pair \(\mathrm{HI}\rm{(aq)}\) and \(\mathrm{NaOH}\rm{(aq)}\) is \[\mathrm{HI}(aq) + \mathrm{NaOH}(aq) \rightarrow \mathrm{NaI}(aq) + \mathrm{H_2O}(l)\]\.

Neutralization Reaction for Pair (b)

The reaction for the pair \(\mathrm{HBr}\rm{(aq)}\) and \(\mathrm{KOH}\rm{(aq)}\) is \[\mathrm{HBr}(aq) + \mathrm{KOH}(aq) \rightarrow \mathrm{KBr}(aq) + \mathrm{H_2O}(l)\]\.

Neutralization Reaction for Pair (c)

The reaction for the pair \(\mathrm{HNO_3}\rm{(aq)}\) and \(\mathrm{Ba(OH)_2}\rm{(aq)}\) is \[\mathrm{HNO_3}(aq) + \mathrm{Ba(OH)_2}(aq) \rightarrow \mathrm{Ba(NO_3)_2}(aq) + 2\mathrm{H_2O}(l)\]\, note that the coefficients are adjusted to balance the equation.

Neutralization Reaction for Pair (d)

The reaction for the pair \(\mathrm{HClO_4}\rm{(aq)}\) and \(\mathrm{Sr(OH)_2}\rm{(aq)}\) is \[\mathrm{HClO_4}(aq) + \mathrm{Sr(OH)_2}(aq) \rightarrow \mathrm{Sr(ClO_4)_2}(aq) + 2\mathrm{H_2O}(l)\]\, also with coefficients adjusted to balance the water molecules.

Key concepts

Acid-Base Reactions

Acid-base reactions, also known as neutralization reactions, are fundamental chemical processes where an acid and a base react to form water and a salt. These reactions are pivotal in various scientific and industrial applications. The general form of an acid-base reaction can be represented as:
\[\text{Acid}(aq) + \text{Base}(aq) \rightarrow \text{Salt}(aq) + \text{Water}(l)\].

Acids are substances that can donate protons (H+ ions) when dissolved in water, while bases are substances that can accept protons. For example, in the reaction between hydroiodic acid (HI) and sodium hydroxide (NaOH), HI acts as the acid and NaOH as the base. When they react, HI donates a proton to the hydroxide ion from NaOH, forming water and an ionic compound called sodium iodide (NaI), the salt. The ability of acids and bases to neutralize each other is widely used to adjust pH in various processes, from industrial manufacturing to biological systems.

Chemical Equations

Chemical equations are concise representations of chemical reactions. They show the reactants (starting substances) and the products (resulting substances) using chemical formulas. These equations are crucial for understanding the nature of the chemical process. Writing a correct chemical equation requires knowledge of the reactants and products, as well as their physical states, indicated as (s) for solid, (l) for liquid, (g) for gas, and (aq) for aqueous or dissolved in water.

For example, the chemical equation for the neutralization reaction between hydrobromic acid (HBr) and potassium hydroxide (KOH) is written as: \[\text{HBr}(aq) + \text{KOH}(aq) \rightarrow \text{KBr}(aq) + \text{H}_2\text{O}(l)\].
In this equation, the reactants are HBr and KOH, and the products are potassium bromide (KBr) and water (H2O). Each formula represents a molecule or compound with specific physical properties and reactivity.

Balancing Chemical Equations

Balancing chemical equations is a vital skill in chemistry, ensuring the law of conservation of mass is upheld. This law states that matter cannot be created or destroyed in a chemical reaction, which means the number of each type of atom must be the same on both sides of the equation. This process may require adjusting coefficients—numbers placed before compounds—to ensure balance.

Take the neutralization reaction between nitric acid (HNO3) and barium hydroxide (Ba(OH)2) as an example: \[\text{HNO}_3(aq) + \text{Ba(OH)}_2(aq) \rightarrow \text{Ba(NO}_3)_2(aq) + \text{H}_2\text{O}(l)\].
Initially, this equation is unbalanced because there are two hydroxide ions on the left but only one water molecule on the right. To balance the equation, we place the coefficient '2' in front of H2O, reflecting that two water molecules form. As a result, the equation adheres to the conservation of mass and becomes balanced. Learning to balance equations not only helps students understand reactions better but also aids in predicting the quantities of products formed in a reaction.