# 12th Chemistry Important Questions Unit 9 Electro chemistry

TN 12th Chemistry Important Questions Unit 9 Electro chemistry. 12th Chemistry Important Questions Chapter 9 Electro chemistry +2 Chemistry Important 2 Marks, 12th Chemistry Important 3 Marks, Chemistry Important 5 Marks Questions Based on reduced Syllabus 2021-2022. 12th Free Online Test (MCQs). HSC 12th Chemistry Revision Test Important Questions. 12th Tamil Full Guide.

## 12th Chemistry Important Questions

## Unit 9 Electro chemistry

### 12th Chemistry All Units Important Questions

### Chapyer 9 – Electro chemistry

- 1. Define anode and cathode
- 2. Why does conductivity of a solution decrease on dilution of the solution
- 3. State Kohlrausch Law. How is it useful to determine the molar conductivity of weak electrolyte at infinite dilution.
- 4. Describe the electrolysis of molten NaCl using inert electrodes
- 5. State Faraday‟s Laws of electrolysis
- 6. The conductivity of a 0.01M solution of a 1 :1 weak electrolyte at 298K is 1.5 ×10
^{-4}Scm^{−1}.

i) molar conductivity of the solution

ii) degree of dissociation and the dissociation constant of the weak electrolyte

Given that λ0_{cation}= 248.2 S cm^{2}mol^{-1}; λ0 = 51.8 S cm^{2}mol^{-1} - 7. Which of 0.1M HCl and 0.1 M KCl do you expect to have greater Λ0
_{m}and why? - 8. Arrange the following solutions in the decreasing order of specific conductance.

i) 0.01M KCl ii)0.005M KCl iii) 0.1M KCl iv) 0.25 M KCl v) 0.5 MKCl - 9. Why is AC current used instead of DC in measuring the electrolytic conductance?
- 10. 0.1M NaCl solution is placed in two different cells having cell constant 0.5 and 0.25cm
^{-1}respectively. Which of the two will have greater value of specific conductance. - 11. A current of 1.608A is passed through 250 mL of 0.5M solution of copper sulphate for 50 minutes. Calculate the strength of Cu
^{2+}after electrolysis assuming volume to be constant and the current efficiency is 100%. - 12. Can Fe
^{3+}oxidises bromide to bromine under standard conditions? Given: E_{Fe3+/Fe2}+=0.771E_{Br2/Br}=-1.09V - 13. Two metals M1 and M2 have reduction potential values of -xV and +yV respectively Which will liberate H2 and H
_{2}SO_{4} - 14. Calculate the standard emf of the cell: Cd| Cd
^{2+}|| Cu^{2+}| Cu and determine the cell reaction. The standard reduction potentials of Cu^{2+}|Cu and Cd^{2+}|Cd are 0.34V and -0.40 volts respectively. Predict the feasibility of the cell reaction. - 15. The same amount of electricity was passed through two separate electrolytic cells containing solutions of nickel nitrate and chromium nitrate respectively. If 2.935g of Ni was deposited in the first cell. The amount of Cr deposited in the another cell? Give : molar mass of Nickel and chromium are 58.74 and 52gm
^{-1}respectively. - 16. A copper electrode is dipped in 0.1M copper sulphate solution at 25
^{o}C . Calculate the electrode potential of copper. [Given: E_{Cu2+/Cu}= 0.34]. - 17. 8.2 ×10
^{12}litres of water is available in a lake. A power reactor using the electrolysis of water in the lake produces electricity at the rate of 2 ×10^{6}Cs^{−1}at an appropriate voltage. How many years would it like to completely electrolyse the water in the lake. Assume that there is no loss of water except due to electrolysis. - 18. Derive an expression for Nernst equation
- 19. Ionic conductance at infinite dilution of Al
^{3+}and SO4^{2-}are 189 and 160 mho cm^{2}equiv^{-1}. Calculate the equivalent and molar conductance of the electrolyte Al_{2}(SO_{4})_{3}at infinite dilution. - 20. Define specific conductance
- 21. Define molar conductivity
- 22. Define equivalent conductivity
- 23. What are the Factors affecting electrolytic conductance?
- 24. Write Applications of Kohlrausch’sLaw
- 25. Define Electro chemical equivalent
- 26. What is Electro chemical series?
- 27. Write a notes on salt bridge
- 28. Define specific resistance
- 29. If the temperature of the electrolytic solution increases, conductance also increases – give the reason.?
- 30. A conductivity cell has two platinum electrodes separated by a distance 1.5 cm and the cross sectional area of each electrode is 4.5sq.cm. Using this cell, the resistance of 1.5N electrolytic solution was measured 15W. Find the specific conductance of the solution.
- 31. The reaction Zn(s) + Co
^{2+}⇌ Co(s) + Zn^{2+}occurs in a cell. Compute the standard emf of the cell. Given that E^{0}_{Zn/Zn2+}= +0.76V, E^{0}Co/Co_{2+}= +0.28V - 32. What are electrochemical series? How is it useful to predict corrosion?
- 33. Write note on standard Hydrogen electrode (SHE)
- The equivalent conductance of M/36 solution of a weak monobasic acid is 6 mho cm
^{2}equiv^{-1}and at infinite dilution is 400 mho cm^{2}equiv^{-1}.Calculate the dissociation constant of this acid.