Electrochemical Cells, Chemical Kinetics, and Catalysis — DU B.Sc (hons) Chemistry Previous Year Question Papers

(b) Construct cell having the reaction H,(g) + ½ for cell potential. 0,(g) → 11,0(1), Write half-cell reactions and expressio (c) Why does a potential develop at the boundary of two electrolyte solutions having same chemical composition but different concentrations? How can this potential be removed? 5 7. (a) Write the electrode reactions, transference reactions and, cell reaction and calculate cell potential for the cell CUSO, (0.02mol kg', Y 7= 0.32)/PbSO (s)/Pb given that trust = 0.37. (b) Compute standard reduction potential for the reaction Cr?t + 2e → Cr from the following data and derive the Nerat equation for the half cell with above reaction. (c) What are reference electrodes ? Give an example of reference electrode along with an expression for its reduction potential. Give one application of a reference electrode. 5 8. (a) Consider the following reaction A _Ky B_K→ C. If and k, =15s" and the reaction is carried out with pure A at initial concentration of 1 moldm-3 what will of 10 mins? be the composition of the reaction mixture after an interval (b) Deseribe the salient features of collision theory for bimolecular reactions ? (e) What are secondary cells? Explain its working using 3, suitable example. Chemical Kinetics and (a) Why is the polarity of electrodes reversed in galvanic and electrolytic cells? (0) Will 'b react with AgNO, ifE® 0.126V Ast/Ag and and E P62+p=- (c) Why is there a potential jump at the equivalence point in the titration of K, CrO, with Mh's salt ? What will be the order of the reaction A + 2B→C? (e) Why does the rate of a reaction usually increase on increasing temperature? (f) Identify the following as initiation, propagation, branching or termination reaction 2. (a) The following data were obtained for dimerization of butadiene according to the equation C,1, → 2C,Hz 5 Show that the reaction is of second order and determine the rate constant. (b) Describe Lindemann mechanism for unimolecular reactions. Under what conditions does the reaction becomes of second (c) Explain the terms enzyme selectivity and specificity giving suitable examples. .. (a The half life of a first order decomposition reaction is 363 min at 298K and the energy of activation is 217.6 kJmol decomposed at 650K. Calculate the time required for 75% of the reactant to be i (b). Setup mechanism of a unimolecular surface catalyzed reaction and derive its rate law. catalyst, promoter and Inhibitor. Explain the following bretty giving example of each 4. . (a). The enzyme catalase catalyses the reaction 2H, 0, (ag) → 2H, 0(1) 0, (g) It has a Michaelis Menten constant of 25 × 103 moldm and a turnover number of 4 × 107s1. If the total concentration of the enzyme is 1.6 × 108-moldm and the initial substrate concentration is 4.32 × 106 moldm" calculate the initial rate and the maximum rate of the reaction. (b) The following mechanism has been suggested for the pyrolysis of monosilane 5 Show that