Classes
Class 9Class 10First YearSecond Year
Q3. Label the sentences as True or False.i) When a reversible reaction attains equilibrium both reactants and products are present in a reaction mixture.ii) The K_{c} of the reaction$\mathrm{A}+\mathrm{B} \square \mathrm{C}+\mathrm{D}$is given by$\mathrm{K}_{\mathrm{c}}=\frac{[\mathrm{C}][\mathrm{D}]}{[\mathrm{A}][\mathrm{B}]}$therefore it is assumed that$[\mathrm{A}]=[\mathrm{B}]=[\mathrm{C}]=[\mathrm{D}]$iii) A catalyst is a substance which increases the speed of the reaction and consequently increases the yield of the product.iv) Ionic product \mathrm{K}_{\mathrm{w}} of pure water at 25^{\circ} \mathrm{C} is 10^{-14} \mathrm{~mol}^{2} \mathrm{dm}^{-6} and is represented by an expression \mathrm{K}_{\mathrm{w}} =\left[\mathrm{H}^{+}\right]\left[\mathrm{OH}^{-}\right]=10^{-14} \mathrm{~mol}^{2} \mathrm{dm}^{-6} v) \mathrm{AgCl} is a sparingly soluble ionic solid in water. Its solution produces excess of \mathrm{Ag}^{+} and \mathrm{Cl}^{-} ions.

Q14 In the equilibrium$\mathrm{PCl}_{5}(\mathrm{~g}) \square \mathrm{PCl}_{3}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g}) \Delta \mathrm{H}=+90 \mathrm{~kJ} \mathrm{~mol}^{-1}$What is the effect on(a) the position of equilibrium(b) equilibrium constant? ifi) temperature is increased

$Q8 (a) Write down \mathrm{K}_{c} for the following reversible reactions. Suppose that the volume of reaction mixture in all the cases is V^{\prime \prime} \mathrm{dm}^{3} at equilibrium stage.V) \mathrm{N}_{2}+3 \mathrm{H}_{2} \square 2 \mathrm{NH}_{3}$

$ii) Which statement about the following equilibrium is correct 2 \mathrm{SO}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \square 2 \mathrm{SO}_{3}(\mathrm{~g}) \ddot{A} \mathrm{H}=-188.3 \mathrm{~kJ} \mathrm{~mol}{ }^{-1} (a) The value of K_{p} falls with a rise in temperature(b) The value of K_{p} falls with increasing pressure(c) Adding \mathrm{V}_{2} \mathrm{O}_{5} catalyst increase the equilibrium yield of sulphur trioxide(d) The value of K_{0} is equal to K_{\text {c. }} .$

$Example:Calculate the \mathrm{pH} of a buffer solution in which 0.11 molar \mathrm{CH}_{3} \mathrm{COONa} and 0.09 molar acetic acid solutions are present. \mathrm{K}_{\mathrm{a}} for \mathrm{CH}_{3} \mathrm{COOH} is 1.85 \times 10^{-5}$

1. For the decomposition of dinitrogen oxide \left(\mathrm{N}_{2} \mathrm{O}\right) into nitrogen and oxygen reversible reaction takes place as follows$2 \mathrm{~N}_{2} \mathrm{O}_{(\mathrm{g})} \rightleftharpoons 2 \mathrm{~N}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})}$The concentration of \mathrm{N}_{2} \mathrm{O} \mathrm{N}_{2} and \mathrm{O}_{2} are 1.1 \mathrm{~mol} \mathrm{dm}^{-3} 3.90 \mathrm{~mol} \mathrm{dm}^{-3} and 1.95 \mathrm{~mol} \mathrm{dm}^{-3} respectively at equilibrium. Find out \mathrm{K}_{\mathrm{c}} for this reaction.

$11. Write note on :(ii) dynamic equilibrium$