What is an acid? Select all that apply. a substance that releases hydrogen ions in water a substance that releases hydroxide ions in water a substance that tastes sour a substance that tastes bitter a substance with a pH below 7
The Correct Answer and Explanation is:
Correct Answers:
- ✅ A substance that releases hydrogen ions in water
- ✅ A substance that tastes sour
- ✅ A substance with a pH below 7
Explanation:
An acid is a chemical substance that has specific properties when dissolved in water or when reacting with other substances. Acids play a vital role in both chemistry and biological systems.
Firstly, according to the Arrhenius definition, an acid is a substance that releases hydrogen ions (H⁺) into an aqueous solution. These hydrogen ions are often associated with hydronium ions (H₃O⁺), which form when H⁺ bonds with water molecules. This property is key in many chemical reactions, especially in acid-base neutralization processes.
Secondly, acids commonly have a sour taste. This can be observed in many common acidic substances like lemon juice (which contains citric acid) and vinegar (which contains acetic acid). While taste is not a reliable or safe method to identify acids in a laboratory setting, it remains a traditional characteristic in descriptive chemistry.
Thirdly, acids are identified on the pH scale, which ranges from 0 to 14. Acids have a pH below 7, with lower values indicating stronger acidity. For example, battery acid (sulfuric acid) has a pH close to 0, while black coffee, a weaker acid, has a pH around 5.
The other choices are incorrect. A substance that releases hydroxide ions is classified as a base, not an acid. Bases tend to taste bitter, not sour. This difference in taste helps differentiate the two in everyday contexts, though again, direct tasting is not advised in chemical testing.
In summary, an acid is a substance that donates hydrogen ions in water, tastes sour, and has a pH below 7.
