Acids and Bases for Kids: The pH Scale Made Simple (Grade 6 and Grade 7 Science)

Hi, I'm Luna from DoodleBeez. What do lemon juice, soap and plain water have in common? They can all be placed on the pH scale. Today we will learn how scientists sort liquids into acids, bases and neutral.

The pH scale runs from zero to fourteen. Seven is right in the middle, and it means neutral. Pure water has a pH of seven. Below seven is acidic, and above seven is basic.

Acids have a pH below seven. They taste sour, like lemons and vinegar. The lower the number, the stronger the acid. Your stomach makes a strong acid, with a pH of about one or two, to help digest food.

Bases have a pH above seven. They often taste bitter and feel slippery, like soap. The higher the number, the stronger the base. Baking soda is about nine, and strong cleaners like bleach can reach about thirteen.

Scientists never taste chemicals to test them. Instead they use an indicator, which changes color. Litmus paper turns red in an acid and blue in a base. Red cabbage juice works too, and makes a rainbow of colors!

When an acid and a base are mixed, they cancel each other out. This is called neutralization. They react to make water and a salt, and the pH moves toward seven. That is how antacid tablets calm an upset stomach.

Now it's your turn. A mystery liquid has a pH of three. Is it an acid, a base or neutral? Pause and try. It is an acid, because three is below seven. It could be something like vinegar.

Great job! Remember, the pH scale goes from zero to fourteen. Seven is neutral, below seven is acidic, and above seven is basic. Indicators show which is which. Practice the pH scale in the Science Lab at doodlebeez.com. See you next time!