(a)(i) Explain what is meant by an effective collision
(ii) What does each term represent in the following expression? \(\Delta G\) = \(\Delta H\) — T\(\Delta\)S
(iii) What deduction can be made about a system given that the value of its \(\Delta\)G is zero?
(b)(i) State Le Chatelier’s principle.
(ii) Suggest three conditions necessary for maximum yield of A\(_2\)B in the reaction represented by the following equation 2A\(_{2(g)}\) + B\(_{2(g)}\) \(\rightleftharpoons\) 2A\(_2\)B\(_{(g)}\) \(\Delta\)H = xkj.
(iii) Write an expression for the equilibrium constant of the reaction in (b)(ii) above.
(c)(i) Give the reason why a log of wood of a given mass does not burn out as quickly as sawdust of the same mass, under the same conditions.
(iii) List two examples of chemical reactions that are catalyzed by light
Explanation
(a)(i) An effective collision is one that results in the formation of the product(s)
(ii) \(\Delta\)G Stands for free energy change. \(\Delta\)H stands for change in heat content or enthalpy; T\(\Delta\)S stands for the entropy term
(iii) The system is in a state of (dynamic) equilibrium
(b)(i) Le Chatelier's principle states that if a chemical system is in equilibrium and one of the factors involved in the system is altered, the equilibrium position will shift so as to annul the effect of the change.
(ii) (1) Increase the pressure
(2) Concentration
(3) Lower the temperature.
(iii) KC = \(\frac{[A_2B]^2}{[A_2]^2[B_2]}\) or KP \(\frac{P^2A_2B}{P^2A_2PB_2}\)
(c)(i) Sawdust has a larger surface area than a log of wood of the same mass. Since reaction rate increases with increase in surface area hence the sawdust burns out faster.
(ii)(i) Grind/Pulverise the wire that will make the particle smaller
(2) Heat the reaction mixture or increase in temperature
(3) Use a more concentrated acid
(iii)(i) Decomposition of silver halides/trioxonitrate (v) (ii) Reaction of methane with chlorine.