Question

Complete and balance each acid-base equation. a. \(\mathrm{H}_{2} \mathrm{SO}_{4}(a q)+\mathrm{Ca}(\mathrm{OH})_{2}(a q) \longrightarrow\) b. \(\mathrm{HClO}_{4}(a q)+\mathrm{KOH}(a q) \longrightarrow\) c. \(\mathrm{H}_{2} \mathrm{SO}_{4}(a q)+\mathrm{NaOH}(a q) \longrightarrow\)

Short answer

a. \(\mathrm{H}_{2} \mathrm{SO}_{4} + \mathrm{Ca}(\mathrm{OH})_{2} \longrightarrow \mathrm{CaSO}_{4} + 2\mathrm{H}_{2}\mathrm{O}\) b. \(\mathrm{HClO}_{4} + \mathrm{KOH} \longrightarrow \mathrm{KClO}_{4} + \mathrm{H}_{2}\mathrm{O}\) c. \(\mathrm{H}_{2} \mathrm{SO}_{4} + 2\mathrm{NaOH} \longrightarrow \mathrm{Na}_{2}\mathrm{SO}_{4} + 2\mathrm{H}_{2}\mathrm{O}\)

Step-by-step solution

Identify the Acid and Base in Each Reaction

For part a, \(\mathrm{H}_{2} \mathrm{SO}_{4}\) is the acid and \(\mathrm{Ca}(\mathrm{OH})_{2}\) is the base. For part b, \(\mathrm{HClO}_{4}\) is the acid and \(\mathrm{KOH}\) is the base. For part c, \(\mathrm{H}_{2} \mathrm{SO}_{4}\) is the acid and \(\mathrm{NaOH}\) is the base.

Write the Products for Each Reaction

The products of an acid-base reaction are typically water and a salt. For part a, water \(\mathrm{H}_{2}\mathrm{O}\) and calcium sulfate \(\mathrm{CaSO}_{4}\) are formed. For part b, water \(\mathrm{H}_{2}\mathrm{O}\) and potassium perchlorate \(\mathrm{KClO}_{4}\) are formed. For part c, again water \(\mathrm{H}_{2}\mathrm{O}\) and sodium sulfate \(\mathrm{Na}_{2}\mathrm{SO}_{4}\) are the products.

Balance the Water Molecules

Since each \(\mathrm{OH}^{-}\) from the base and each \(\mathrm{H}^{+}\) from the acid come together to form \(\mathrm{H}_{2}\mathrm{O}\), we need to balance the number of hydroxide ions and hydrogen ions to determine how many water molecules are produced.

Balance the Salts

For the salts, we need to ensure that the cations from the base match the number of anions from the acid to form a neutral salt.

Balance the Complete Equation

Using coefficients, we ensure the equation is balanced with the same number of each type of atom on both sides of the equation.

Key concepts

Acid-Base Reactions

Acid-base reactions are a foundational concept in chemistry, often categorized by the transfer of a proton (a hydrogen ion, \( H^+ \) ) from an acid to a base. An acid is a substance that can donate a hydrogen ion, while a base is one that can accept it. When acids and bases are mixed, they react to form water (\( H_2O \) ) and a salt, which is referred to as the products of a neutralization reaction.

To understand acid-base reactions, one must be familiar with the concept of ionization. Acids ionize in water to produce hydrogen ions, whereas bases produce hydroxide ions (\( OH^- \) ). The strength of an acid or base is determined by its ability to donate or accept hydrogen ions. For instance, \( HCl \) (hydrochloric acid) is considered a strong acid as it completely ionizes in solution, whereas \( CH_3COOH \) (acetic acid) is a weak acid because it only partially ionizes.

Here are some properties of acids and bases:

• Acids taste sour and turn blue litmus paper red.
• Bases taste bitter, feel slippery, and turn red litmus paper blue.
• Strong acids and bases can be corrosive, while weak acids and bases are generally less harmful.

In the textbook exercise, acids such as sulfuric acid (\( H_2SO_4 \) ) and perchloric acid (\( HClO_4 \) ) are reacting with bases like calcium hydroxide (\( Ca(OH)_2 \) ) and potassium hydroxide (\( KOH \) ), demonstrating the classic acid-base reaction leading to the production of water and a respective salt.

Chemical Equation Balancing

Balancing chemical equations is a crucial skill in chemistry that involves making sure the number of each type of atom and the total charge is the same on both sides of the equation. The Law of Conservation of Matter states that matter cannot be created or destroyed in an ordinary chemical reaction. Therefore, what goes into a reaction must come out in some form, and balancing the equation validates this law.

To balance a chemical equation, start by writing the unbalanced equation. Make a list of the number of atoms for each element present in both reactants and products. Then, adjust coefficients (the numbers in front of compounds or elements in the equation) to ensure that there are equal numbers of each atom on both sides. It's important to remember that you can only change coefficients and not the subscripts in chemical formulas because changing a subscript would change the compound's identity.

For example, to balance the equation \( H_2 + O_2 \rightarrow H_2O \) you'd adjust the coefficients to \( 2H_2 + O_2 \rightarrow 2H_2O \), ensuring there are 4 hydrogen atoms and 2 oxygen atoms on both sides. The goal is to have the smallest whole number coefficients without fractions. In the exercise provided, part a presented \( H_2SO_4 + Ca(OH)_2 \rightarrow H_2O + CaSO_4 \) which has to be balanced step by step, considering the number of \( H^+ \) and \( OH^- \) ions to balance both water molecules and salts.

Neutralization Reactions

Neutralization reactions are a category of acid-base reactions where an acid reacts with a base to produce salt and water. This type of reaction is important not only in chemical analysis but also has practical applications, such as antacid medications relieving heartburn by neutralizing excess stomach acid. The general form of a neutralization reaction is:\[ \text{Acid} + \text{Base} \rightarrow \text{Water} + \text{Salt} \]

In a neutralization reaction, the \( H^+ \) ions from the acid combine with the \( OH^- \) ions from the base to form water (\( H_2O \) ), and the remaining ions form the salt. Not all neutralization reactions involve strong acids and strong bases; weak acids or weak bases can also participate, and the resulting pH of the solution can be neutral, acidic, or basic, depending on the strengths of the reactants:

• A strong acid and a strong base will typically result in a neutral solution (\( pH = 7 \)).
• A strong acid and a weak base will yield an acidic solution (\( pH < 7 \)).
• A weak acid and a strong base will create a basic solution (\( pH > 7 \)).

Referring back to the textbook exercise, by combining \( HClO_4 \) and \( KOH \) as in part b, we see a neutralization reaction where potassium perchlorate (\( KClO_4 \) ) and water are the products. These reactions are not only simple to understand but also serve as a great example of acid-base behavior in aqueous solutions.