Q10 of 22 Page 1

Calculate the time to deposit 1.27 g of copper at cathode when a current of 2 A was passed through the solution of CuSO4. (Molar mass of Cu = 63.5 g mol−1, 1 F = 96500 C mol−1)

Given, mass of Cu deposited (z) = 1.27 g


Current, I = 2A


Molar mass of Cu = 63.5 g mol−1, 1 F = 96500 C mol−1


Reaction taking place: Cu2+ + 2e-→ Cu


By Faraday’s first law,


W= zQ (since, Q = It)


W = zIt …(1)


Where, W, amount of substance deposited = 1.27g


I, current = 2A and t = time


Z = =


Substituting all values in equation (1),


1.27 =


t = 1930 s


Therefore, time to deposit 1.27 g of copper at cathode is 1930s.


More from this chapter

All 22 →
8

Write the reagents required in the following reactions:

(i) CH2 = CH − CH2OH ¾ CH2 = CH − CHO


(ii) CH3− COOH ¾ CH3− CONH2


OR


Arrange the following compounds in increasing order of their property as indicated:


(i) CH3COCH3, C6H5COCH3, CH3CHO (reactivity towards nucleophilic addition reaction)


(ii) Cl − CH2− COOH, F − CH2− COOH, CH3 − COOH (acidic character)


 9

(i) On mixing liquid X and liquid Y, volume of the resulting solution decreases. What type of deviation from Raoult’s law is shown by the resulting solution? What change in temperature would you observe after mixing liquids X and Y?

(ii) What happens when we place the blood cell in water (hypotonic solution)? Give reason.


 11

A solution is prepared by dissolving 10 g of non-volatile solute in 200 g of water. It has a vapour pressure of 31.84 mm Hg at 308 K. Calculate the molar mass of the solute. (Vapour pressure of pure water at 308 K = 32 mm Hg)

 12

(i) Name the method of refining to obtain silicon of high purity. (ii) What is the role of SiO2 in the extraction of copper?

(iii) What is the role of depressants in froth floatation process?