Acids and Bases

Acids and Bases

pH - potential of Hydrogen

pH measures how acidic or basic a substance is, using a scale from 0 to 14.

A pH of 7 is neutral, below 7 is acidic, and above 7 is basic (alkaline).

Acids

• Acids have a pH less than 7 and produce H⁺ ions in water.

• Acids release hydrogen ions (H⁺) when dissolved in water, making the solution more acidic.

• The more H⁺ ions in a solution, the stronger the acid.

Bases

• Bases have a pH greater than 7 and produce OH⁻ ions in water.

• Bases release hydroxide ions (OH⁻) when dissolved in water, making the solution more alkaline.

• Strong bases can neutralize acids by reacting with H⁺ ions to form water.

Strong vs Weak

Weak acids and bases partially dissociate, releasing fewer ions (e.g., vinegar, ammonia).

Weak

Strong acids and bases fully dissociate in water, releasing more H⁺ or OH⁻ ions e.g., HCl, NaOH.

Strong

Neutralisation Reaction

When acids and bases react, they form water and a salt. This is called neutralisation.

Example: HCl + NaOH → NaCl + H₂O

Multiple Choice

What does pH measure?

• The amount of water in a substance

• The temperature of a solution

• How acidic or basic a substance is

• The amount of sugar in a solution

Multiple Choice

What is the pH of a neutral substance?

• 0

• 7

• 14

• 10

Multiple Choice

Which of the following is a characteristic of an acid?

• Produces OH⁻ ions in water

• Has a pH above 7

• Feels slippery to the touch

• Produces H⁺ ions in water

Multiple Choice

What is the pH range of strong acids?

• 7-14

• 4-7

• 0-3

• 8-14

Categorize

Options (7)

Lemon juice

Vinegar

Stomach acid

Baking soda

Soap

Ammonia cleaner

Pure water

Classify the following substances as acid, base, or neutral.

Acid

Base

Neutral