Seema took a small amount of copper powder in a china dish and heated it. What changes will she observe on…
Seema took a small amount of copper powder in a china dish and heated it. What changes will she observe on heating ? When H2 gas is passed over this heated substance, what visible changes will be seen in it ? Give the chemical equations of the reactions involved, along with the names and colours of the products in each case.
Solution
• Colour of copper powder changes from brown to black.
• On passing H2 gas, the colour turns brown.
•
heat
2Cu + O2 → 2CuO ½+ ½
copper oxide
(Black)
heat
CuO + H 2 → Cu + H 2O ½+ ½
copper (Brown)
(Award ½ mark for equation and ½ mark for name and colour in each
case.)
