15
Answer the following :
(a) Write two observations when green coloured crystals of ferrous sulphate are heated in a boiling tube.
(b) Why brown coloured copper powder turns black on heating ?
(c) What happens when limestone is heated strongly ?
(a) Write two observations when green coloured crystals of ferrous sulphate are heated in a boiling tube.
(b) Why brown coloured copper powder turns black on heating ?
(c) What happens when limestone is heated strongly ?
Show SolutionHide Solution↓
(a) • Green colour of the crystal changes brown. (½ Mark)
• Colourless gases with odour of burning sulphur. (½ Mark)
(any other observation)
(b) Copper changes to copper (II) oxide which is black in colour. /
$\ce{2Cu(s) + O2(g) ->[Heat] 2CuO(s)}$ (Brown to Black) (1 Mark)
(Award full marks if chemical equation with colour changes is written)
(c) Calcium oxide (quick lime) and colourless gas ($\ce{CO2}$) is evolved /
$\ce{CaCO3(s) ->[Heat] CaO(s) + CO2(g)}$ (1 Mark)
• Colourless gases with odour of burning sulphur. (½ Mark)
(any other observation)
(b) Copper changes to copper (II) oxide which is black in colour. /
$\ce{2Cu(s) + O2(g) ->[Heat] 2CuO(s)}$ (Brown to Black) (1 Mark)
(Award full marks if chemical equation with colour changes is written)
(c) Calcium oxide (quick lime) and colourless gas ($\ce{CO2}$) is evolved /
$\ce{CaCO3(s) ->[Heat] CaO(s) + CO2(g)}$ (1 Mark)