**Acids and Bases: An Overview**

Acids and bases are two fundamental concepts in chemistry. They are substances that have distinct properties and play essential roles in various chemical reactions.

**Acids: Definition and Properties**

Acids are substances that can donate protons (H+) or accept a pair of electrons during a chemical reaction. This ability to donate protons is what gives acids their characteristic properties. Some key features of acids include:

1. **Sour taste**: Many acids, such as lemon juice or vinegar, have a sour taste.
2. **Corrosive**: Acids can corrode certain materials, such as metals or skin, due to their ability to react with them.
3. **Turn litmus paper red**: Litmus paper is a pH indicator that turns red in the presence of acids.
4. **Release hydrogen gas**: When an acid reacts with certain metals, it produces hydrogen gas.
5. **Conduct electricity**: Acids in solution can conduct electricity due to the presence of ions.

**Acidic Solutions and pH Scale**

Acids are often dissolved in water to form acidic solutions. The concentration of hydrogen ions (H+) in a solution determines its acidity. The pH scale is used to measure the acidity or basicity of a solution. It ranges from 0 to 14, with pH 7 considered neutral, pH less than 7 acidic, and pH greater than 7 basic.

**Common Examples of Acids**

There are various types of acids, including:

1. **Hydrochloric acid (HCl)**: Found in our stomach, it aids in digestion.
2. **Sulfuric acid (H2SO4)**: Widely used in industries for various purposes.
3. **Citric acid**: Found in citrus fruits like lemons and oranges.
4. **Acetic acid (CH3COOH)**: Present in vinegar.
5. **Carbonic acid (H2CO3)**: Formed when carbon dioxide dissolves in water.

**Bases: Definition and Properties**

Bases, also known as alkalis, are substances that can accept protons (H+) or donate a pair of electrons during a chemical reaction. Some key features of bases include:

1. **Bitter taste**: Many bases, such as baking soda, have a bitter taste.
2. **Slippery feel**: Bases can feel soapy or slippery when touched.
3. **Turn litmus paper blue**: Litmus paper turns blue in the presence of bases.
4. **Release hydroxide ions**: Bases produce hydroxide ions (OH-) in solution.
5. **Conduct electricity**: Bases in solution can conduct electricity due to the presence of ions.

**Basic Solutions and pH Scale**

Bases are often dissolved in water to form basic solutions, which have a higher concentration of hydroxide ions (OH-). The pH scale is also used to measure the basicity of a solution. Basic solutions have a pH greater than 7.

**Common Examples of Bases**

Some common examples of bases include:

1. **Sodium hydroxide (NaOH)**: Commonly known as caustic soda, it is used in manufacturing processes.
2. **Ammonia (NH3)**: Used in household cleaning products.
3. **Baking soda (NaHCO3)**: Used in cooking and cleaning.
4. **Magnesium

Acid, any substance that in water solution tastes sour, changes the colour of certain indicators (e.g., reddens blue litmus paper), reacts with some metals (e.g., iron) to liberate hydrogen, reacts with bases to form salts, and promotes certain chemical reactions (acid catalysis).