Q94 of 400 Page 195

No chemical reaction takes place when granules of a rusty-brown solid A are mixed with the powder of another solid B. However, when the mixture is heated, a reaction takes place between its components. One of the products C is a metal and settles down in the molten state while the other product D floats over it. It was observed that the reaction is highly exothermic.

(a) What could the solids A and B be?


(b) What are the products C and D most likely to be?


(c) Write the chemical equation for the reaction between A and B leading to the formation of C and D.


(d) What is the special name of such a reaction? State one use of such a reaction.


(e) Name any two types of chemical reactions under which the above reaction can be classified.

(a) From the above given statement solid A is iron (III) and the solid B is aluminium.

(b) The products C and D most likely to be iron and aluminium oxide respectively.


(c) The chemical equation for the reaction between A and B leading to the formation of C and D is like



Mention the physical states of all the reactants and products in this equation and indicate the heat change which takes place.


(d) The special name of such a reaction is Thermite reaction. One use of such a reaction is in Welding of broken pieces of heavy iron objects like railway tracks, etc.


(e) The two types of chemical reactions under which the above reaction can be classified are displacement reactions and Oxidation-reduction reactions.



More from this chapter

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92 An element A which is a part of common salt and kept under kerosene reacts with another element B of atomic number 17 to give a product C. When an aqueous solution of product C is electrolyzed then a compound D is formed and two gases are liberated.

(a) What are A and B?


(b) Identify C and D.


(c) What will be the action of C on litmus solution? Why?


(d) State whether element B is a solid, liquid or gas at room temperature.


(e) Write formula of the compound formed when element B reacts with an element E having atomic number 5.

 93 A metal which exists as a liquid at room temperature is obtained by heating its sulphide ore in the presence of air.

(a) Name the metal and write its chemical symbol.


(b) Write the name and formula of the sulphide ore.


(c) Give the equations of chemical reactions involved in the production of metal from its sulphide ore.


(d) Name a common 'device in which this metal is used.


(e) Can this metal displace copper from copper sulphate solution? Why?

 95 In an electrolytic tank, aluminium metal is being extracted by the electrolysis of molten aluminium oxide using carbon electrodes. It is observed that one of the carbon electrodes is gradually burnt away and has to be replaced.

(a) Which carbon electrode (cathode or anode) is burnt away?


(b) Why is this carbon electrode burnt away?

 96 A metal X which is resistant to corrosion is produced by the electrolysis of its molten oxide whereas another metal Y which is also resistant to corrosion is produced by the reduction of its oxide with carbon. Metal X can be used in powder form in thermite welding whereas metal Y is used in making cathodes of ordinary dry cells.

(a) Name the metals X and Y.


(b) Which of the two metals is more reactive: X or Y?


(c) Name one ore or metal X. Also write its chemical formula.


(d) Name one ore of metal Y. Also write its chemical formula.


(e) Name one alloy of metal X and one alloy of metal Y.