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ICSE Class 8 Chemistry Question 17 of 18

Hydrogen — Question 5

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Question 10

State a reason why, when hydrogen is passed over heated copper oxide, the resultant product formed, differs in colour from the original reactant.

Answer

As hydrogen is a strong reducing agent hence it reduces heated copper (II) oxide to copper. Therefore, the original black copper (II) oxide changes to reddish brown copper.

CuO[black]+H2⟶Cu[reddish brown]+H2O\underset{\text{[black]}}{\text{CuO}} + \text{H}_2 \longrightarrow \underset{\text{[reddish brown]}}{\text{Cu}} + \text{H}_2\text{O}