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Why will the colour of heated copper pow...

Why will the colour of heated copper powder become black when air is passed over it?

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### Step-by-Step Solution: 1. **Understanding the Initial Condition**: - We start with copper powder, which is a reddish-brown solid. 2. **Heating the Copper Powder**: - When copper powder is heated, it becomes more reactive. ...
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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.

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.

A blue coloured salt of copper sulphate becomes white on heating. Give reason.

Why does nitric oxide become brown when released in air ?

When the powder of a common metal is heated in an open china dish, colour turns black. However, when hydrogen gas is passed over the hot black substance formed, it regains its original colour. Based on this information, answer the following questions : (i) What type of chemical reaction takes place in each of the two given steps ? (ii) Name the metal initially taken in the powder form. Write balanced chemical equations for both these reactions.

When ammonia is passed over heated copper oxide, the metallic coper is obtained. The reaction shows that ammonia is :

(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.

VK GLOBAL PUBLICATION-CHEMICAL REACTIONS AND EQUATIONS-VERY SHORT ANSWER QUESTIONS
  1. What is wrong with the following equation? Mg+OrarrMgO Identify th...

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  2. Potassium chlorate (KClO(3)) on heating forms potassium chloride and o...

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  3. On heating blue coloured powder of copper(II) nitrate in a boiling tub...

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  4. Convey the following information in the form of a balanced chemical eq...

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  5. Balance the following chemical equation: Pb(NO(3))(2)(s)overset("Hea...

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  6. Give one example of a combination reaction which is also exothermic.

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  7. Why will the colour of heated copper powder become black when air is p...

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  8. What is the difference between the following two types of reactions? ...

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  9. Why is hydrogen peroxide kept in coloured bottles?

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  10. Consider the following reactions: (i) Fe+CuSO(4)rarrFeSO(4)+Cu (ii...

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  11. Give one example of a reaction which is a double displacement reaction...

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  12. Why is photosynthesis considered an endothermic reaction ?

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  13. What type of reaction is represented by the digestion of food in our b...

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  14. How will you test for the gas which is liberated when hydrochloric aci...

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  15. Can a double displacement reaction take place when the products are hi...

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  16. What changes in the colour of iron nails and copper sulphate solution ...

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  17. Name the oxidising and reducing agent in the following reaction: 2H(...

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  18. A dilute ferrous sulphate solution was gradually added to the beaker c...

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  19. Define rancidity.

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  20. Name one synthetic antioxidant.

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