alkaline

Everyday

1. Alkaline describes a substance that is the opposite of an acid: it has a pH above 7, such as soap, baking soda or bleach. tree →
2. An alkaline battery is a common kind of battery that uses an alkaline chemical inside. tree →

In the lessons

In science lessons, the pH scale goes from 0 to 14: acids are below 7, neutral is 7 (pure water), and alkaline is above 7. Indicators such as red cabbage juice or litmus change colour: alkalis turn red litmus blue. Strong alkalis like bleach and oven cleaner can burn skin, so safety goggles and gloves are needed. Some soils are alkaline, which matters to gardeners.

Examples

• Soap is slightly alkaline. tree →
• Red litmus paper turns blue in an alkaline solution. tree →
• Baking soda makes the water alkaline. tree →
• Bleach is strongly alkaline, so handle it with care. tree →
• The TV remote uses alkaline batteries. tree →
• Some plants grow best in alkaline soil. tree →
• Our cabbage indicator turned green in the alkaline liquid. tree →

Note

Adjective only. The noun is alkali (plural alkalis). Opposite: acidic. A substance that is neither is neutral. Trap: alkaline does not mean safe; strong alkalis are as dangerous as strong acids. Myth: alkaline water does not change the pH of your blood.