Metallurgy Archives - Page 9 Of 9

In the extraction of aluminium :
(i) Which soln. is used to react with bauxite as a first step in obtaining pure aluminium oxide.
(ii) The aluminium oxide for the electrolytic extraction of aluminium is obtained by heating aluminium hydroxide. Write the equation for this reaction.
(iii) Name the element which serves as the anode and cathode in the extraction of aluminium.
(iv) Write equation for the reaction at the cathode during the extraction of aluminium by electrolysis.
(v) Give the equation for the reaction at the anode when aluminium is purified by electrolysis.

(i) Sodium hydroxide is used to react with bauxite as a first step in obtaining pure aluminium oxide. (ii) Conversion of Al(OH)3 - to pure alumina by heating Al(OH)3 2Al(OH)3 Al2O3 + 3H2O…

When a metal atom becomes an ion : [Choose the correct answer from the choices A, B, C and D]
A : it loses electrons and is oxidized
B : it gains electrons and is reduced
C : it gains electrons and is oxidized
D : it loses electrons and is reduced

it loses electrons and is oxidized Reason — metals readily give the valence electron during reactions and are hence oxidised.

A strip of copper is placed in four different colourless salt solutions. They are KNO3, AgNO3, Zn(NO3)2, Ca(NO3)2. Which one of the solutions will finally turn blue.

Silver Nitrate (AgNO3) Reason — Copper displaces silver from AgNO3 soln. forming the blue copper [II] nitrate soln.

Name the following :
(i) A metal which is liquid at room temperature.
(ii) A compound added to lower the fusion temp. of the electrolytic bath in the extraction of Al.
(iii) The process of heating an ore to a high temperature in the presence of air.

(i) Mercury is liquid at room temperature. (ii) Cryolite [Na3AlF6] is added to lower the fusion temp, of the electrolytic bath in the extraction of Al (iii) Roasting is the process of heating an ore to…

Calcium, Copper, Lead, Aluminium, Zinc, Chromium, Magnesium, Iron. Choose the major metals from the list given above to make the following alloys :
(i) Stainless steel
(ii) Brass.

(i) Iron and Chromium are used to make stainless steel (ii) Copper and Zinc are used to make brass.

A to F below relate to the source and extraction of either Zinc or aluminium
A : Bauxite,
B : Coke,
C : Cryolite,
D : Froth floatation,
E : Sodium hydroxide solution,
F : Zinc blended.
(i) Write down the three letters each from the above list which are relevant to – Aluminium.
(ii) Fill in the blanks using the most appropriate words from A to F :
(a) The ore from which aluminium is extracted must first be treated with …………… so that pure Aluminium oxide can be obtained.
(b) Pure Aluminium oxide is dissolved in …………… to make a conducting solution.
(iii) Write the formula of Cryolite.

(i) A : Bauxite and C : Cryolite are ores of aluminium. E : Sodium hydroxide solution is used in the dressing of the ore. (ii) Fill in the blanks : (a) The ore…

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