Chemical Equilibrium, Ionic Equilibrium, Conductance, and Solid State — DU B.Sc (hons) Chemistry Previous Year Question Papers

Conductance and Solid State (a) What is Walden's rule? Explain, why is it not applicable to cations of small size. (b) For the reaction, S02(g) + ≤ 0z(g) = S03(g) at 25°C, the standard molar Gibb's free energy of formation (4G,) of SO2(g) and SO3(g) are - 300 kJ mol' and -371 kJ mol-!. What will be the equilibrium constant (Kp) at this temperature? (R = 8.314 J mol ' K-1) (c) How is conductivity water prepared? The specific conductance of a solution prepared in this conductivity water is 0.176 S cm-' If the cell constant is 0.225 cm-', calculate the conductance (2-') of the solution. (d) What is the ionic product of water? Comment on "pH of water is 7 at 25°C but at other temperature, it may be more or less than 7.00". (e) What will be the entropy of mixing (JK-') when three moles of helium are mixed with one mole of neon at constant temperature and pressure (25°C and 1 atm.)? (t) What is the buffer solution? Explain it with appropriate examples. (g) Explain the law of rational indices and the law of symmetry? 2. (a) Derive the quantitative equations of Le Chatelier's principle. With the help of the principle, comment on the conditions of temperature and pressure that would favour the formation of nitric oxide in the following reaction. (b) What is meant by the degree of advancement of a chemical reaction and derive the law of chemical reaction for the ideal gas reaction, (c) Show with a diagram that the greatest decrease in Gibbs free energy on mixing is associated with formation of mixture having equal number of moles of two constituents. (d) Calculate the equilibrium constant (K) for a reaction, 25O,(g) = 250, (g) + O,(g) for which Kp is 3.5 × 10-23 atm at 27°C and the gas constant (R) is 3. (a) Show that the pH of a hydrolysed salt from a weak acid and a weak base can be determined through following equation: (b) A buffer solution is made of 0.2 moles of HA and 0.25 moles of NaA per litre. Calculate the change in pH of the solution if 0.1 mL of 1 M NaOH is added to it. Assume that the volume of the buffer remains unchanged. Provided: (KHA=1.0 × 10→). (c) Calculate the solubility in grams per litre of Al(OH, in water at 25°C when its solubility product is 8.5 × 10-32. (d) The base ionization constant (k) of ammonia in water is 1.8x10-s. What should be the value of acid ionization constant (k) of the conjugate acid? (4,4,4,3) 4. (a) What is meant by transport number of an ion? Explain the factors on which the transport number of an ion depends? (b) The conductivities of water and a saturated solution of a sparingly soluble salt, AB, are 7 and 21 uS m-' and ionic conductivities of cation and anion of AB, are 12.72 uS m? mol' and 7.64 mS m'mol-!. What is the solubility of AB,? (c) The specific conductance of 0.01 M solution of acetic acid was found to be 0.01 S2-1 m. Calculate the degree of dissociation of the acid when the limiting molar conductance of acetic acid is 400 × 10-4 2-' m'mol!.