Quiz Questions. 1. There are three methods of preparing salts. Method A – use a burette and an indicator. Method B – mix two solutions and obtain the salt by precipitation. Method C – add an excess of base or a metal to a dilute acid and remove the excess by filtration. For each of the following salt preparations, choose one of the methods A, B or C, name any additional reagent needed and then write or complete the equation. i) the soluble salt, zinc sulphate, from the insoluble base, zinc oxide method : ……………………………………………………………………………………… reagent : ……………………………………………………………………………………… word equation : ……………………………………………………………………………...[3] ii) the soluble salt, potassium chloride, from the soluble base, potassium hydroxide method : ……………………………………………………………………………………… reagent : ………………………………………………………………………………………... equation : ……… +………….. → KCl + H2O [3] (iii) the insoluble salt, lead(II) iodide, from the soluble salt, lead(II) nitrate method : ………………………………………………………………………………………... reagent : ………………………………………………………………………………………... equation : Pb2+ +…………….. →……………… [4] 2. A length of magnesium ribbon was added to 50 cm3 of sulfuric acid, concentration 1.0 mol / dm3. The time taken for the magnesium to react was measured. The experiment was repeated with the same volume of different acids. In all these experiments, the acid was in excess and the same length of magnesium ribbon was used. (a) (i) Write these experiments in order of reaction speed. Give the experiment with the fastest speed first. …………................................................................................................................................ [1] (ii) Give reasons for the order you have given in (i). ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ................................................................................................................................................ [5] (b) Suggest two changes to experiment C which would increase the speed of the reaction and explain why the speed would increase. The volume of the acid, the concentration of the acid and the mass of magnesium used were kept the same. change 1 ........................................................................................................................... explanation ....................................................................................................................... ........................................................................................................................................... change 2 ........................................................................................................................... explanation ....................................................................................................................... ..................................................................................................................................... [5] [Total: 11]
