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Chemistry & Chemical Reactivity
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Chapter 21 / Exercise 48
Chemistry & Chemical Reactivity
Kotz/Treichel
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Section A(Answer ALLquestions in this Section.)1.Rubidium (Rb) and potassium belong to the same group in the Periodic Table. The relativeatomic mass of rubidium is larger than that of potassium.(a)Explain whether rubidium is more reactive than potassium.(b)Write a chemical equation for the reaction between rubidium and water. (Statesymbols should be given.)(c)Suggest how rubidium can be stored safely in the laboratory.(d)Suggest ONE safety precaution for handling rubidium in the laboratory.(5 marks)
12.In each of the following groups of substances, there is ONE substance which is differentfrom the others in terms of their properties. In each group, identify the substance which isdifferent from the others and explain your choice.(a)argon, fluorine, helium, neon(b)nylon, perspex, polyethene, urea-methanal(c)milk of magnesia, soap, vinegar, window cleaner(d)carbon monoxide, hydrogen, methane, nitrogen(8 marks)2.(a)fluorinefluorine is reactive/yellow/coloured gas1+1or, others are inert/unreactive/stable/colourless (gases).(DO NOT accept noble gas/halogens.group VII (0) element)(b)Urea-methanalIt is a thermosetting plastic (cannot be softened by heat)/the othersubstances are thermoplastics (can be softened by heat)1+1(c)VinegarIt is acidic/the others are alkaline1+1(d)NitrogenIt cannot burn in air/the others can burn in air1+13.Some of the ingredients present in a certain brand of cheese sticks are as follows:benzoic acid, corn meal, cheese, monosodium glutamate (MSG),sunset yellow (E110), vegetable oilWhich of the above ingredients are food additives? Suggest ONE function for each of thefood additives.(6 marks)
(3 marks for the correct choice of 3 food additives, if more than 3 substances areFor questions 4 and 5, candidates are required to give paragraph-Iength answers. 3 out ofthe marks for each of these two questions will be awarded for the effective communicationof knowledge in Chemistry.
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Chemistry & Chemical Reactivity
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Chapter 21 / Exercise 48
Chemistry & Chemical Reactivity
Kotz/Treichel
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