While cookies may be sweet, some of their ingredients, like baking soda, are very bitter. The taste of baking soda is due to the fact that its pH is very basic, or alkaline.

An alkaline solution has an increased concentration of hydroxide ions. The opposite of alkaline is acidic: sour foods, like lemons and vinegar, are acidic. Acidic solutions have an increased concentration of hydronium ions. You may know that mixing baking soda (which is high in hydroxide ions) with vinegar (which has more hydronium ions) can create a terrific explosion! This is because when you mix an acid with a base, the exchange of atoms releases energy. Cooking is just one situation in which knowing pH is important.

“Hydronium” refers to a positively charged ion formed when a hydrogen ion (H+) combines with a water molecule (H2O).

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