(a) (i) Define nuclear fission. (ii) A certain natural decay series starts with \(^{238}_{92}U\) and ends with\(^{230}_{90}Th\). Each step involves the loss of an alpha or a beta particle. Using the given information, deduce how many alpha beta particpes were emitted. (b) Consider the equilibrium reaction represented by the following equation: A\(_{2(9)}\) + 3B\(_{2(9)}\) \(\rightleftharpoons\) 2AB\(_{3(g)}\); \(\Delta\)H = + xkJmol\(^{-1}\) Explain briefly the effect of each of the following changes on the equilibrium composition: (i) increase in concentrat of B; (ii) decrease in pressure of the system; (iii) addition of catalyst. (c) The lattice energies of three sodium halides are as follows:
Compound
NaF
NaBr
Nal
Lattice energy/kJmol\(^{-1}\)
890
719
670
Explain briefly the trend. (d) State the property exhibited by nitrogen (IV) oxide in each of the following reactions: (i) 4Cu + 2NO\(_2\) \(\to\) 4CuO + N\(_2\); (ii) H\(_2\)O + 2NO\(_2\) \(\to\) HNO\(_3\) + HNO\(_2\). (e) Iron is manufacturcd in a blast furnace using iron ore (Fe\(_2\)O\(_3\)), coke and limestone. Write the equation for the reaction(s) at the: (i) top of the furnace; (ii) middle of the furnace; (iii) bottom of the furnace. (f) (i) Name two products of destructive distillation of coal. (ii) Give one use of each product in (f)(i).
Explanation
(a)(i) It is the splitting of a heavy nucleus into smaller nuclei accompanied by the release of large amount of energy. (ii)\(^{238}_{92}U\) and ends with\(^{230}_{90}Th\) + \(2^{4}_{2}He\) + \(2^{o}_{-1e}Th\) \(\alpha\) [articles = 2 \(\beta\) particles = 2
(b)(i) Equilibrium positicn shifts to the right and more of AB\(_3\) is formed or decrease in concentration of A\(_2\) (ii) Equilibrium shifts to the left and more of A\(_2\) and; B\(_2\) formed / decrease in concentration of AB\(_3\) (iii) No effect. Catalyst affects both forward and backward reactions equally.
(c) For a constant cation Na\(^+\) lattice energy decreases with ircreases in size of the anion / decrease in electronegativity of the anion. F\(^-\), Br\(^-\), I\(^-\) increasing order of size. Hence the decreasing crder ofilattice energy.
(d)(i) NO\(_2\) is an oxidizing agent (ii) NO\(_2\) is acting as an oxidizing as well as reducing agents OR acid anhydride.
(e)(i) Fe\(_2\) O\(_3\) + 3CO --> 2Fe + 3CO\(_2\) (ii) CaCO\(_3\) —› CaO + CO\(_2\), CaO + SiO\(_2\) \(\to\) CaSiO3 (iii) C + O\(_2\) —> CO\(_2\), CO\(_2\) + C \(\to\) 2CO
(f) Coke I Coal Tar / Coal Gas /Ammonical Liquor (ii) Coke — Solid fuels I production of water gas, extraction of ME Coal Tar — Synthesis of chemicals — perfumes, dyes, paints, drugs, plastic and explosives, etc. Coal Gas — as fuels in homes and industries Ammonical liquor — production of (NH\(_4\))\(_2\) SO\(_4\) for fertilizer
