Why is a coloured solution formed in the reaction of copper oxide with dilute acid?
Answer and explanation
Correct answer: Copper salt forms
The governing reaction is neutralisation between a metal oxide and an acid. Copper oxide reacts with dilute hydrochloric acid to form copper chloride and water: CuO + 2HCl → CuCl₂ + H₂O. Dissolved copper(II) ions give the solution its characteristic blue-green colour. Therefore a copper salt forms; sugar, hydrogen gas, or water alone cannot explain the colour.
Frequently asked questions
What is the correct answer to this question?
Copper salt forms
Why is this the correct answer?
The governing reaction is neutralisation between a metal oxide and an acid. Copper oxide reacts with dilute hydrochloric acid to form copper chloride and water: CuO + 2HCl → CuCl₂ + H₂O. Dissolved copper(II) ions give the solution its characteristic blue-green colour. Therefore a copper salt forms; sugar, hydrogen gas, or water alone cannot explain the colour.
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.
