What is Acid? Definition, Meaning & Example
A substance that contains hydrogen ions and turns blue litmus paper red, with pH less than 7.
TL;DR: A substance that contains hydrogen ions and turns blue litmus paper red, with pH less than 7.
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Acid: A substance that contains hydrogen ions and turns blue litmus paper red, with pH less than 7.
Explanation
Acids are compounds that release hydrogen ions (H+) when dissolved in water. Common acids include hydrochloric acid in the stomach, citric acid in lemons, and acetic acid in vinegar. The strength of an acid depends on how completely it releases hydrogen ions. Strong acids like hydrochloric acid completely dissociate, while weak acids like acetic acid only partially dissociate. Acids react with bases to form salt and water in neutralization reactions. In India, the pH scale is taught to measure acidity, where pH 0-6 indicates acidic substances, pH 7 is neutral, and pH 8-14 indicates basic substances.
Example
Lemon juice contains citric acid, which makes it sour. When you add lemon juice to blue litmus paper, it turns red, confirming the presence of acid.
Frequently Asked Questions
What makes a substance acidic?
A substance is acidic when it contains hydrogen ions (H+) that are released when it dissolves in water, or when its pH is less than 7.
Are all acids dangerous?
No, some acids like citric acid in fruits are safe to eat, while others like sulfuric acid are extremely dangerous and corrosive.
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