What is the difference between an acid and a base?
Acids release hydrogen ions in water and taste sour, like lemon juice. Bases accept hydrogen ions, taste bitter and feel slippery, like soap. They are measured on the pH scale.
The pH scale runs from 0 to 14. Pure water is neutral at pH 7. Acids have a pH below 7, such as vinegar at about 3 and stomach acid at about 1.5 to 3.5. Bases, also called alkalis when they dissolve in water, have a pH above 7, such as baking soda at about 8 or 9 and bleach at about 12 or 13.
When an acid and a base react, they neutralize each other, producing water and a salt. This is why antacid tablets, which are mildly basic, can relieve heartburn caused by stomach acid. Strong acids and bases, such as hydrochloric acid and sodium hydroxide, can burn skin and must be handled carefully.
Testing acidity
Scientists use indicators that change color depending on pH. Litmus paper turns red in acids and blue in bases. Red cabbage juice works as a natural indicator, turning pink in acids and green or yellow in bases.
Did You Know?
Hydrangea flowers can change color depending on soil pH, producing blue flowers in acidic soil and pink flowers in more alkaline soil.