Science · Physical Science

Acids and Bases — Reading Comprehension Lesson

Reading comprehension passage and printable worksheet about acids, bases, and the pH scale for grades 3–6.

Reading Passage

Acids and Bases

Acids and bases are two important groups of chemicals found all around us. Many of the foods we eat, the cleaning products in our homes, and even the chemicals in our own bodies are either acids or bases. Chemists study acids and bases to understand how different substances react with one another.

An acid is a substance that has a sour taste and can react with metals to release hydrogen gas. Common examples include the citric acid in lemons and oranges, the acetic acid in vinegar, and the hydrochloric acid that helps your stomach digest food. Strong acids can be dangerous and need to be handled carefully.

A base is a substance that often feels slippery and tastes bitter. Bases include things like baking soda, soap, and ammonia. When a base mixes with water, it produces hydroxide ions. Like acids, some bases are mild, but others are very strong and can burn skin if not handled safely.

Scientists measure how acidic or basic a substance is using a number scale called pH. The pH scale runs from 0 to 14. A pH of 7 is neutral — water is a good example. Numbers below 7 are acidic, and the lower the number, the stronger the acid. Numbers above 7 are basic, and the higher the number, the stronger the base.

When an acid and a base are combined, they react in a process called neutralization. The acid and base cancel each other out, often producing water and a salt. This is why people who have heartburn sometimes take antacids — the basic medicine helps neutralize extra stomach acid and ease the pain.

Printable Worksheet

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