pH Scale, Strong vs Weak Acids/Bases, and Titration Curves

Understanding the pH Scale

The pH scale measures how acidic or basic a solution is. It ranges from 0 to 14:

• Acidic solutions have a pH less than 7.
• Neutral solutions have a pH of 7.
• Basic (alkaline) solutions have a pH greater than 7.

The pH scale is logarithmic, meaning each whole number change on the scale represents a tenfold change in acidity or basicity.

Strong vs Weak Acids and Bases

Acids and bases can be classified as strong or weak based on their ability to dissociate in water:

• Strong acids/bases dissociate completely in water. Examples include hydrochloric acid (HCl) and sodium hydroxide (NaOH).
• Weak acids/bases only partially dissociate in water. Examples include acetic acid (CH₃COOH) and ammonia (NH₃).

Titration Curves

A titration curve is a graph showing the change in pH as a titrant is added to a solution. It helps identify the equivalence point, where the amount of acid equals the amount of base.

For weak acid-strong base titrations:

• The initial pH is higher than that of a strong acid.
• The pH rises gradually at first, then more steeply as it approaches the equivalence point.
• The equivalence point is above pH 7, indicating a basic solution.