# Lesson Plan: The pH Scale Chemistry • 7th Grade

This lesson plan includes the objectives, prerequisites, and exclusions of the lesson teaching students how to define pH as a logarithmic measure of acid concentration and use it to determine the relative acidity or basicity of a substance.

#### Objectives

Students will be able to

- recall that pH is a relative measure of acidity and basicity,
- define pH in qualitative terms as a logarithmic measure of the concentration of ions,
- draw and interpret a pH scale including common acids and bases,
- identify acids and bases from their pH values,
- estimate the pH values of common acids and bases (e.g., lemon juice),
- understand and explain the change in pH during an experiment (e.g., adding powdered calcium hydroxide to dilute hydrochloric acid),
- describe the use of simple indicators to provide an approximation of the pH of a solution (e.g., litmus paper, universal indicators).

#### Prerequisites

Students should already be familiar with

- acidity and basicity.

#### Exclusions

Students will not cover

- quantitative descriptions of pH,
- calculations of pH,
- the relationship between pH, pKa, and other dissociative constants.