pH Scale Lesson for Kids: Definition & Facts

Instructor: Elizabeth Foster

Elizabeth has been involved with tutoring since high school and has a B.A. in Classics.

Scientists use the pH scale to measure how basic (alkaline) or acidic things are. Learn about the pH scale and take a look at some familiar foods and cleaning products with different pHs, like water, milk, and baking soda.

Using pH in Your Life

Have you ever tasted a lemon and puckered up? Lemons have that puckery taste because they're acidic, just like vinegar and some other foods. In this lesson, you'll learn about the pH scale, which scientists use to describe whether something is acidic or basic. Basic is the opposite of acidic. Another word for 'basic' is 'alkaline:' they mean the same thing.

The pH Scale

The pH scale goes from 0 to 14: 0 is the most acidic and 14 is the most basic, or alkaline.

the pH scale
pH scale

So if something has a low pH (close to 0), then it's very acidic, and if it has a high pH (close to 14), it's very basic or alkaline. Plain water is right in the middle of the scale with a pH of 7. This is called a neutral pH, because it's not very acidic or very basic (alkaline).

pH in Real Life

To get a better idea of pH, it can help to look at some examples from real life. We'll start with the middle of the pH scale: with a pH of 7, plain water is exactly in the center. So if you want to feel and taste something with a neutral pH, go pour yourself a glass of water and take a big drink.

Acidic pH

Moving on down the scale towards things with a more acidic pH, you could try some milk: milk has a pH between 6 and 7, so it's just a little more acidic than water. If you drank some coffee instead of milk, you'd be down to a pH of 5. If you had some grapefruit juice, you'd be looking at a pH around 3, and ordinary vinegar has a pH of 2.

Coffee has a pH around 5.

Below a pH of 2, things aren't safe for people to eat. For example, battery acid has a pH close to 0, but you'd definitely never eat that!

Basic (Alkaline) pH

Now let's head back to our neutral pH of 7 - remember, that's a glass of plain water - and go up the scale to look at things that are more basic or alkaline than water. The first step up from tap water is...sea water! If you took a cup of water out of the ocean instead of pouring it from a faucet, the pH would be about 8.

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