In one roasting unit, 1000 kg of an ore concentrate of the composition given below is roasted using excess air ni3s 21% fes 40% sio2 31% h20 8% the roasting unit is heated by oil of composition 85% cand 15% h, the amount of oil is 6.2 % of the weight of the ore. the gases from combustion and roasting mix together and are carried through as flue gases s is converted to so2 the roasted product consists of nio, fe: o, and sio2 and the roasting reactions are given as; ni3s27/2023nio 250 2 2fes2 11/202 fe2o3 4s0 (i) explain how you would increase the kinetics of roasting and hence the production rate (5 marks) (i) calculate: a) weight of roasted product (10 marks) volume of the fuel oil given that its density is 0.89 g/cm2 (5 marks) b) volume of so2 in m2 (5 marks) c) (note: atomic weights are ni 59, fe 56, s 32, o= 16, h - 1 )

7. using your knowledge of colligative properties explain whether sodium chloride or calcium chloride would be a more effective substance to melt the ice on a slick sidewalk. use 3 – 4 sentences in your explanation. 8. when a 2.5 mol of sugar (c12h22o11) are added to a certain amount of water the boiling point is raised by 1 celsius degree. if 2.5 mol of aluminum nitrate is added to the same amount of water, by how much will the boiling point be changed? show all calculations leading to your answer or use 3 – 4 sentences to explain your answer. 9. if 5.40 kcal of heat is added to 1.00 kg of water at 100⁰c, how much steam at 100⁰c is produced? show all calculations leading to an answer. 10. the freezing of water at 0⁰c can be represented as follows: h2o (l) ↔ h2o(s) the density of liquid water is 1.00 g/cm3. the density of ice is 0.92 g/cm3. in 3 – 4 sentences explain why applying pressure causes ice to melt.

Which type of precipitation would most likely form when the surface air temperature is slightly below freezing and the air temperature increases as you move upward away from the ground?

)benzene and toluene form nearly ideal solutions. consider an equimolar solution of benzene and toluene. at 20 °c the vapour pressures of pure benzene and toluene are 9.9 kpa and 2.9 kpa, respectively. the solution is boiled by reducing the external pressure below the vapour pressure. calculate (i) the pressure when boiling begins, (ii) the composition of each component in the vapour, and (iii) the vapour pressure when only a few drops of liquid remain. assume that the rate of vaporization is low enough for the temperature to remain constant at 20 °c.