When acid and base are added dropwise separately to a solution, its pH changes each time. What does this show?
Answer and explanation
Correct answer: pH depends on the balance of hydrogen and hydroxide ions
The governing concept is that pH reflects the relative concentration of hydrogen ions and hydroxide ions in an aqueous solution. Adding an acid generally increases hydrogen-ion concentration, so pH decreases. Adding a base increases hydroxide-ion concentration and usually lowers the relative hydrogen-ion concentration, so pH increases. Colour and the container do not determine pH, and pH can change readily. Therefore option A is correct.
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What is the correct answer to this question?
pH depends on the balance of hydrogen and hydroxide ions
Why is this the correct answer?
The governing concept is that pH reflects the relative concentration of hydrogen ions and hydroxide ions in an aqueous solution. Adding an acid generally increases hydrogen-ion concentration, so pH decreases. Adding a base increases hydroxide-ion concentration and usually lowers the relative hydrogen-ion concentration, so pH increases. Colour and the container do not determine pH, and pH can change readily. Therefore 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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