Home >> Science & Nature >> Science

How to Use a pH Scale Worksheet

The pH scale measures how acidic or basic a substance is. The lower, or closer to 0, a substance is on the logarithmic pH scale, the more acidic it is. Substances higher on the scale are less acidic, or more basic. The middle of the scale is 7, which is considered neutral and is the pH of pure water. The scale measures the concentration of hydrogen ions in a substance. The higher the concentration of hydrogen items, the more acidic a substance is. To make the pH scale more understandable, a worksheet may contain examples of substances for each number on the scale.

Instructions

- 1
  Look at how the scale is marked. Some scales will run horizontally, while others will run vertically. It will be laid out with the most acidic substance on the left or at the top, while the most basic or most alkaline substances will be to the right or at the bottom.
- 2
  Read the numbers on the scale. The lower the number, the more acidic a substances is. So numbers from 0 to 4 are highly acidic to acidic. Numbers from 5 to 7 are less acidic to neutral. Substances from 8 to 14 are increasingly basic.
- 3
  Brush up on your exponents and logarithms, which will help you understand the pH scale. A difference of 1 in pH is equivalent to 10 times the difference in acidity. For example 2 on the pH scale is 10 times more acidic than 3, 100 times more acidic than 4 and 1,000 times more acidic than 5. In terms of exponents, a pH of 2 is 10^5, or 100,000 times, more acidic than neutral 7, which is five places higher on the scale.
- 4
  Look at numbers higher than 7, which is neutral on the pH scale. Any number higher than 7 on the scale is less acidic by a negative exponent. For example, 11 is 10 times less acidic than 10, 100 times less acidic than 9 and 1,000 times less acidic than 8. In terms of exponents, a pH of 11 is 10^-4, or 1/10,000, as acidic as neutral 7, which is four places lower on the scale.
- 5
  Read the examples next to the numbers. These are representative substances that have, or are close to, the pH values indicated by each number. Battery acid may represent 0 pH, which is very acidic, while black coffee may be at 5 on the scale, which is slightly acidic. Baking soda may represent a pH of 9, which is slightly basic, and a pH of 14, or very basic, may be represented by liquid drain cleaner.

Science