Scientists Say: Alkaline

This is an adjective for a chemical base

a photo of brown hands washing with soap and water

Alkaline substances are basic chemicals. Some basic chemicals, when combined with oils or fats, can make soap.

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Alkaline (adjective, “AL-kah-line”)

This word describes a chemical that is basic. A basic chemical is one that produces hydroxide ions (-OH) in solution. These chemicals have a pH higher than 7.0.

The word “alkaline” comes from the word alkali, which refers to salts of alkali metals. Alkali metal salts such as sodium bicarbonate — or baking soda — are always basic, and so alkaline can now be used to describe any chemical that is a base.

Both alkaline and alkali come from the Arabic word “al-qili.” This is the word for the ashes of saltwort plants. Once these plants are burned, their ashes produce a strong base. That base is the salt of the alkali metal potassium. When alkaline chemicals like these are mixed with oil or other fats, they form soap.

In a sentence

The right alkaline chemicals could help astronauts make soil-based concrete on Mars.

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Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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