Acid and Alkali Concepts

Acid and Alkali Concepts

• Indicator: A dye that changes color in the presence of acids or alkalis.
• Neutral: Refers to a substance with a pH of 7, indicating it is neither acidic nor alkaline.

pH Scale

• pH Scale: Ranges from 1 to 14, measuring acidity or alkalinity.
  • Acids: pH below 7.
  • Neutral substances: pH of 7.
  • Alkalis: pH greater than 7.

Chemical Processes

• Chemical Reaction: Involves a transformation where new substances are created.
• Neutralisation: A reaction between an acid and an alkali (or base) resulting in the formation of salt and water.

Chemical Entities

• Products: New substances formed during a chemical reaction, located on the right side of a word equation.
• Reactants: The starting substances in a chemical reaction, noted on the left side of a word equation.
• Salt: The substance produced (apart from water) when an acid reacts with an alkali or base.

Practical Applications

• Antacid: A remedy for indigestion, containing a base that neutralises excess stomach acid.
• Base: Any substance that can neutralize an acid, yielding a salt and water in the process.

pH Values

• pH 2: Highly acidic.
• pH 4: Mildly acidic.
• pH 5: Slightly acidic.
• pH 7: Neutral.
• pH 7.4: Slightly basic, typical for bodily fluids.
• pH 10: Mildly basic.
• pH 12: Strongly basic.