On heating copper powder in air, the surface of copper powder becomes coated with black CuO. How can this black coating be converted into brown copper ? Write chemical equation for the reaction that occurs during the colour change.

On heating copper powder in air, the surface of copper powder becomes coated with black CuO. How can this black be converted into brown copper? Write chemical equation for the reaction that occurs during the colour change.

(a) Write the chemical equation in the balanced form. Fe(s) + H_(2)O(g) to Fe_(3)O_(4)(s) + H_(2)(g) (b) Identify the type of reaction from the equation given below : Na_(2)SO_(4)(aq) + BaCl_(2) (aq) to BaSO_(4)(s) + NaCI(aq) (c) You could have noted that when copper powder is heated in a china dish, the surface of copper powder gets coated with black coloured substance. (i) Why is this black coloured substance formed ? (ii) What is this black substance ? (iii) Write the chemical equation of the reaction taking place.

You are given the following materials : {:((i), "Iron nails",, (ii), "Copper sulphate solution"),((iii), "Barium chloride solution",, (iv), "Copper powder"),((v), "Ferrous sulphate crystals",, (vi), "Quick lime"):} Identify the type of chemical reaction taking place when : (a) Barium chloride solution is mixed with copper sulphate solution and a white precipitate is observed. (b) On heating, copper powder in air in a china dish, the surface of copper powder becomes black. (c) On heating green ferrous sulphate crystals, reddish brown solid is left and a gas having smell of burning sulphur is noticed. (d) Iron nails when left dipped in blue copper sulphate solution becomes brownish in colour and blue colour of copper sulphate solution fades away.

Why does the colour of copper sulphate solution change when an iron nail is dipped in it ? Write chemical equation for the reaction involved.

When copper powder is heated, it gets coated with Black copper oxide Yellow copper oxide Red copper oxide Brown copper oxide

You are given the following materials: (i) Iron nails (ii) Copper sulphate solution (iii) Barium chioride solution (iv) Copper powder (v) Ferrous sulphate crystals (vi) Quicklime Identify the type of chemical reaction taking place when: (a) Barium chloride solution is mixed with copper sulphate solution and a white precipitate is observed. (b) On heating copper powder in air in a china dish, the surface of copper powder turns black. (c) On heating green coloured ferrous sulphate crystals,reddish brown solid is left and smell of a gas having odour of burning sulphur is experienced. (d) Iron nails when left dipped in blue copper sulphate solution become brownish in colour and the blue colour of copper sulphate fades away. (e) Quick lime reacts vigorously with water releasing a large amount of heat. Write chemical equations for each one of the above reactions

A copper plate was dipped into a solution of AgNO_(3) . After sometime, a black layer was deposited on the copper plate. State the reason for it. Write the chemical equation for the reaction involved.

Write the chemical equation for tranishing of silver wear (black coatings on silver).