Acids, bases, and pH are fundamental concepts in chemistry that describe the properties and behaviors of substances.
Acids:
- Definition: Acids are substances that can donate a proton (H⁺ ion) in a chemical reaction. They have a pH less than 7.
- Characteristics:
- Taste sour (e.g., citric acid in lemons).
- Can turn blue litmus paper red.
- React with bases to form salts and water (neutralization).
- Common examples include hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and acetic acid (CH₃COOH).
Bases:
- Definition: Bases are substances that can accept a proton or donate a hydroxide ion (OH⁻) in a chemical reaction. They have a pH greater than 7.
- Characteristics:
- Taste bitter and feel slippery (e.g., soap).
- Can turn red litmus paper blue.
- React with acids to form salts and water (neutralization).
- Common examples include sodium hydroxide (NaOH), potassium hydroxide (KOH), and ammonia (NH₃).
pH:
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Definition: pH is a measure of the acidity or basicity of a solution. It is a logarithmic scale that quantifies the concentration of hydrogen ions (H⁺) in a solution.
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Scale:
- The pH scale typically ranges from 0 to 14.
- pH < 7: Acidic solution (higher concentration of H⁺ ions).
- pH = 7: Neutral solution (pure water).
- pH > 7: Basic (alkaline) solution (lower concentration of H⁺ ions).
- The pH scale typically ranges from 0 to 14.
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Calculation: pH is calculated using the formula:
\[ \text{pH} = -\log[H^+] \]
where \([H^+]\) is the molar concentration of hydrogen ions in the solution.
Together, these concepts help in understanding chemical reactions, biological processes, and environmental science, among other fields.