What is the difference between an acid and a base?

Verified step by step guidance

1. An acid is a substance that donates hydrogen ions (H⁺) or protons in a chemical reaction, while a base is a substance that accepts hydrogen ions (H⁺) or protons.
2. In aqueous solutions, acids increase the concentration of hydronium ions (H₃O⁺), while bases increase the concentration of hydroxide ions (OH⁻).
3. Acids typically have a pH less than 7, whereas bases have a pH greater than 7. A pH of 7 is considered neutral.
4. Acids often taste sour (e.g., citric acid in lemons), while bases tend to taste bitter and feel slippery (e.g., soap).
5. The reaction between an acid and a base is called a neutralization reaction, which typically produces water (H₂O) and a salt as products.

Key Concepts

Acids

Acids are substances that can donate protons (H⁺ ions) in a chemical reaction. They typically have a sour taste and can turn blue litmus paper red. Acids are characterized by their ability to increase the concentration of hydrogen ions in a solution, which can lead to a decrease in pH. Common examples include hydrochloric acid (HCl) and sulfuric acid (H₂SO₄).

Bases

Bases are substances that can accept protons or donate hydroxide ions (OH⁻) in a chemical reaction. They usually have a bitter taste and can turn red litmus paper blue. Bases increase the concentration of hydroxide ions in a solution, resulting in an increase in pH. Common examples include sodium hydroxide (NaOH) and ammonia (NH₃).

pH Scale

The pH scale is a measure of the acidity or basicity of a solution, ranging from 0 to 14. A pH of 7 is considered neutral, while values below 7 indicate acidity and values above 7 indicate basicity. The scale is logarithmic, meaning each whole number change represents a tenfold change in hydrogen ion concentration. Understanding the pH scale is essential for distinguishing between acids and bases.