Question

Explain why salts can be acidic, basic, or neutral, and show examples. Do this without specific numbers

Short answer

Salts can be acidic, basic, or neutral depending on the properties of the cation and anion they consist of, as they are derived from the reactions between acids and bases. Acidic salts, such as ammonium chloride (NH4Cl), are formed when a strong acid reacts with a weak base, and they increase the concentration of H+ ions in a solution, lowering the pH. Basic salts, like sodium acetate (CH3COONa), are formed when a weak acid reacts with a strong base and decrease the concentration of H+ ions in the solution, raising the pH. Neutral salts, like sodium chloride (NaCl), result from the reaction between a strong acid and a strong base, and their cations and anions have no significant effect on the H+ or OH- concentrations, leading to a neutral solution with a pH close to 7.

Step-by-step solution

Introduction to Salts

Salts are ionic compounds formed when an acid reacts with a base. They consist of positively charged cations and negatively charged anions. The properties of the cation and anion in the salt determine whether the salt will be acidic, basic, or neutral.

Acidic Salts

Acidic salts are formed when a strong acid reacts with a weak base. In this case, the cation from the strong acid tends to donate a proton (H+) in solution, while the anion from the weak base accepts the proton poorly, resulting in a net increase in the concentration of H+ ions in the solution. This causes the solution to become acidic, with a pH less than 7. Example: Ammonium chloride (NH4Cl) is an example of an acidic salt. It is formed from the reaction between hydrochloric acid (a strong acid) and ammonia (a weak base). In water, the ammonium ion (NH4+) can donate a proton to water molecules, forming hydronium ions (H3O+), which lowers the pH of the solution.

Basic Salts

Basic salts are formed when a weak acid reacts with a strong base. In this case, the anion from the weak acid tends to accept a proton (H+) in solution, while the cation from the strong base donates the proton poorly, resulting in a net decrease in the concentration of H+ ions in the solution. This causes the solution to become basic, with a pH greater than 7. Example: Sodium acetate (CH3COONa) is an example of a basic salt. It is formed from the reaction between acetic acid (a weak acid) and sodium hydroxide (a strong base). When dissolved in water, the acetate ion (CH3COO-) can accept a proton from water molecules, forming the weak acid acetic acid, and leaving behind hydroxide ions (OH-), which raises the pH of the solution.

Neutral Salts

Neutral salts are formed when a strong acid reacts with a strong base. In this case, cations from the strong acid react with anions from the strong base to form a salt, but neither the cation nor the anion has a significant effect on the acidity or basicity of the solution. As a result, the salt becomes neutral, with a pH of approximately 7. Example: Sodium chloride (NaCl), commonly known as table salt, is an example of a neutral salt. It is formed from the reaction between hydrochloric acid (a strong acid) and sodium hydroxide (a strong base). When dissolved in water, neither the sodium ions (Na+) nor the chloride ions (Cl-) have a significant effect on the H+ or OH- concentrations, resulting in a neutral solution with a pH close to 7.

Key concepts

Acidic Salts

Acidic salts are fascinating compounds formed when a strong acid reacts with a weak base. This combination often results in a bit of a power struggle within the solution. The cation from the strong acid, usually potent at donating protons (H+), significantly influences the acidity. Coupled with an anion from the weak base that isn't very good at accepting protons, this leads to an increase in the concentration of hydrogen ions in the solution. This increase nudges the pH below 7, making the solution acidic.

A common example of an acidic salt is ammonium chloride (\( \text{NH}_4\text{Cl} \)). When ammonium chloride dissolves in water, the ammonium ion (\( \text{NH}_4^+ \)) can donate a proton to water, forming hydronium ions (\( \text{H}_3\text{O}^+ \)). This process lowers the pH, creating a more acidic environment. Isn't it intriguing how the nature of the initial acid-base combination influences the resulting characteristics of the solution?

• Formed by strong acids and weak bases
• Solution pH is less than 7
• Example: Ammonium chloride

Basic Salts

Basic salts are created when a weak acid joins forces with a strong base. Such combinations flip the scenario seen with acidic salts. Here, the anion from the weak acid is better at accepting protons compared to the cation's ability from the strong base to donate them.This tendency results in a decrease of hydrogen ion concentration in the solution, effectively increasing the pH beyond 7 and rendering the solution basic.

An illustrative example of a basic salt is sodium acetate (\( \text{CH}_3\text{COONa} \)). In water, the acetate ion (\( \text{CH}_3\text{COO}^- \)) can easily accept a proton, forming acetic acid, and simultaneously releasing hydroxide ions (\( \text{OH}^- \)). These hydroxide ions elevate the basicity of the solution. Isn't it interesting how a weak ingredient like acetic acid significantly contributes to forming a basic solution?

• Formed by weak acids and strong bases
• Solution pH is greater than 7
• Example: Sodium acetate

Neutral Salts

Neutral salts arise from the union of a strong acid with a strong base. In these cases, the interaction is more balanced, leading to neither significant contribution to the solution's overall pH.The ions involved do not have a considerable impact on modifying hydrogen or hydroxide ion concentrations, maintaining a pH approximately close to neutral, which is around 7.

A classic example is sodium chloride (\( \text{NaCl} \)), commonly known as table salt. Sodium chloride results from the reaction of hydrochloric acid and sodium hydroxide. When dissolved in water, neither the sodium ions (\( \text{Na}^+ \)) nor the chloride ions (\( \text{Cl}^- \)) alter the concentration of hydrogen or hydroxide ions, thus ensuring the solution remains neutral. It's quite fascinating how nature ensures balance with such combinations.

• Formed by strong acids and strong bases
• Solution pH is around 7
• Example: Sodium chloride