The temperature rises slightly when sodium hydroxide is added to an acidic solution. What is the reason?
Answer and explanation
Correct answer: Neutralisation releases heat
When sodium hydroxide is added to an acid, hydroxide ions combine with hydrogen ions to form water: H+ + OH- -> H2O. This acid-base process is neutralisation, and the formation of water is generally exothermic, so some energy is released as heat and the temperature rises. The sodium hydroxide does not simply become a gas, the acid does not become a metal, and salt formation does not freeze water. Thus option A is correct.
Frequently asked questions
What is the correct answer to this question?
Neutralisation releases heat
Why is this the correct answer?
When sodium hydroxide is added to an acid, hydroxide ions combine with hydrogen ions to form water: H+ + OH- -> H2O. This acid-base process is neutralisation, and the formation of water is generally exothermic, so some energy is released as heat and the temperature rises. The sodium hydroxide does not simply become a gas, the acid does not become a metal, and salt formation does not freeze water. Thus option A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
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