General Principles and Processes of Isolation of Elements Test

These equilibria can be discussed in terms of thermodynamic functions.

For the reaction :

(i) $$\displaystyle M_{(s)} + \frac{1}{2} O_{2(g)} \rightarrow MO_(s)$$

(ii) $$\displaystyle \frac{1}{2} C_{(s)} + \frac{1}{2} O_{2(g)} \rightarrow \frac{1}{2} CO_{2(g)}$$

(iii) $$\displaystyle C_{(s)} + \frac{1}{2} O_{2(g)} \rightarrow CO_{(g)}$$

(iii) $$\displaystyle CO_{(g)} + \frac{1}{2} O_{2(g)} \rightarrow CO_{2(g)}$$

The temperature dependence of $$\Delta \mathring{G}$$ of reaction (i) to (iv) is shown in the given diagram. This is known as the Ellingham diagram. With the help of the Ellingham diagram, one can easily predict the most suitable reducing agent for the reduction of metal oxides.

$$AI_2O_3$$ can be reduced by carbon at a temperature of:

General Princip...

Question 1

$$ZnO, Fe_2O_3, SnO_2$$

$$ZnO, SnO_2, MgO$$

$$MgO, Al_2O_3$$

$$MgO, SnO_2, Al_2O_3$$,

Question 2

$$CuFeS_2$$

$$MgCl_2.6H_2O$$

$$Al_2O_3.2H_2O$$

$$Fe_2O_3$$

Question 3

distillation process

cupellation

liquation

Bett's electrolysis

Question 4

Upto 710$$^{\circ}$$C, the reaction of forrnation of $$CO_2$$ is energetically more favorable, but above 710$$^{\circ}$$C, the formation of CO is preferred.

In principle, carbon can be used to reduce any metal oxide at a sufficiently high temperature.

$$\Delta S(C_{(s)} + 1/2 O_{2(g)} \longrightarrow CO_{(g)}) < \Delta S (C_{(S)} + O_{2(g)} \longrightarrow CO_{2(g)}$$

Carbon reduces many oxides at elevated temperature because $$\Delta G$$ vs temperature line has a negative slope.

Question 5

distillation

poling

liquation

reduction

Question 6

cathode

anode

electrolyte

none of these

Question 7

lies above the line for one of the reactions (ii) to (iv)

intersects the line for one of the reactions (ii) to (iv)

lies below the line for one of the reactions (ii) to (iv)

may lie above or below the line for one of the reactions (ii) to (iv) depending upon the temperature

Question 8

approximately equal to room temperature

above room temperature

below room temperature

at all temperature

Question 9

$$Na_3GeF_6$$

$$Na_3AlF_6$$

$$Al_2O_3$$

none of these

Question 10

$$30^{\circ}$$C

$$500^{\circ}$$C

$$2000^{\circ}$$C

$$> 2500^{\circ}$$C

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