DPS - MIS, DOHA QATARAssignmentClass XII Chemistry Date:11/05/2015 Last date for submission 14th May 20151. .Formulate the galvanic cell in which the following reaction takes place.Zn(s) +2 Ag+ (aq) Zn2+ (aq) +2Ag (s)a. Which one of its electrodes is negatively charged?b. The reaction taking place at each of its electrode.c. The carriers of current within this cell.2. In the button cell , widely used in watches , the following reaction takes placeZn(s) + Ag 2O (s) + H2O Zn 2+ (aq) +2 Ag(s) +2OH- (aq)(Given E0 Ag+/Ag = +0.80V, E0Zn2+/Zn = -0.76V) Determine E0and G 0 for the reaction.3. A voltaic cell is set up at 25o C with the following half cells Al/Al3+ (0.001M) and Ni/Ni2+(0.50M)Write an equation for the reaction that occurs when the cell generates an electric current and determine the cell potential. E0 Ni2+/Ni = -0.25V, E0 Al3+/Al = -1.66V (log 8x10-6 = -5.0969)4. Determine the values of equilibrium constant (Kc) and G 0 for the following reaction. Ni(s) +2Ag+ (aq) Ni2+ (aq) + 2Ag(s) Eo =1.05V, (1F= 96500 C/mol)5. Write the Nernst equation and compute the emf of the following cell at 298 K. Sn(s) / Sn2+ (0.05M) // H+ (0.02M)/ H2, 1atm/Pt, [ E0= Sn2+/Sn = -0.144V]6. How is molar conductivity related to conductivity?7. State and explain Kohlrauschs law of independent migration of ions. Write an expression for the molar conductivity of acetic acid at infinite dilution according to Kohlrauch law.8. Define molar conductivity of a substance and describe how for weak and strong electrolytes, molar conductivity changes with concentration of solute. How is such change explained?9. Calculate the degree of dissociation of acetic acid at 298 k , given that m( CH3COOH) =11.7 Scm2/mol, 0m (CH3COO-)= 40.9 Scm2/mol, 0m(H+) =349.1 Scm2/mol10. The resistance of a conductivity cell containing 0.001 M KCI solution at 298K is1500. What is the cell constant if the conductivity of 0.001M KCl solution at 298K is 0.146 x 10-3 S/ cm?11. Conductivity of 0.00241 M acetic acid solution is 7.896 x10-5 S cm-1. Calculate its molar conductivity in this solution If 0m for acetic acid be 390.5 Scm2/mol, what would be its dissociation constant?12. What type of battery is the lead storage battery? Write the anode and the cathode reactions and the overall reaction occurring in a lead storage battery when current is drawn from it.13. Mention the reactions occurring at a) anode & b)cathode, during working of a mercury cell. Why does the voltage of a mercury cell remain constant during its operation?14. Give an example of a fuel cell and write the cathode and anode reactions for it.15. What is a nickel cadmium cell? State its one merit and one demerit over lead storage cell. Write the overall reaction that occurs during discharging of this cell.16. Silver is electrodeposited on a metallic vessel of total surface area 900cm2 by passing a current of 0.5A for 2 hrs. Calculate the thickness of silver deposited. Given density of silver = 10.5g/cm3.17. Identify the reaction order from the following rate constant, k= 2.3 x 10-5L/mol/s18. For the reaction Cl2(g) + 2 NO(g) 2NOCl(g). The rate law is expressed as rate= k[Cl2] [NO2]2. What is the overall order of this reaction?19. Express the rate of the following reaction in terms of disappearance of hydrogen in the reaction. 3H2(g) + N2 (g) 2NH3(g)20. For the reaction, A B the rate of reaction becomes 27 times when the concentration of A is increased 3 times. What is the order of the reaction?21. A reaction is of second order with respect to a reactant. How is its rate affected if the concentration of the reactant is (i) doubled (ii) reduced to half.22. Distinguish between the rate expression and rate constant of a reaction.23. Distinguish between molecularity and order of a reaction.24. For a chemical reaction, what is the effect of a catalyst on the following?i) Activation energy of the reaction ii) Rate constant of the reaction.25. Nitric oxide reacts with hydrogen to give nitrogen and water.2NO + 2H2 N2 + 2H2O. the kinetics of this reaction is explained by the following steps.i) 2NO + H2 N2 + H2O2 (slow)ii) H2O2 + H2 2H2O (fast) What is the predicted rate law?26. The data given below is for the reaction 2N2O5 4NO2 + O2Sl.noN2O5 mol/LRate of disappearance of N2 O5(mol/L/min)

11.13 x 10-234 x 10-5

20.84 x 10-225 x10-5

30.62 x 10-218 x10-5

Determine for this reactioni) Order of reaction ii) Rate law iii) Rate constant27. The rate constant for a zero order reaction in A is 0.0030mol/L/s. How long will it take for the initial concentration of A to fall from0.1M to 0.075M?28. A first order reaction is 20% complete in 5 min. Calaculate the time taken for the reaction to be 60% complete.29. A certain reaction is 50% complete in 20 min at 300K and the same reaction is again 50% complete complete in 5 min at350K. Calculate activation energy if it is first order reaction.[R =8.314J/K/mol]30. The activation energy for the reaction 2HI(g)H2(g) + I2(g) is 209.5kJ/mol at 581K.Calculate the fraction of molecules having energy equal to or greater than activation energy.

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