2024 4N Acids Bases 2024 with answers

4N Acids & Bases Clinic Name:…………………………………………………….. Date: 6 September 2024 1 Reactions involving acids 1 2 3 C A D

2 pH scale 4 5 6 B B B

3 7 8 Types of Oxides 9 D A B

4 10 11 12 13 B C B B

5 14 (a) Write the formula for the ion which makes hydrochloric acid, HCl, acidic. H+[1] (b) Name the ion present in aqueous sodium hydroxide, NaOH, that makes it an alkali. Hydroxide [1] (c) (i) Name the type of reaction which occurs between hydrochloric acid and sodium hydroxide. Neutralisation [1] (ii) Name the salt produced in this reaction. Sodium chloride [1] (iii) Write the chemical equation for this reaction. HCl + NaOH → NaCl + H2O [1] 15 Indigestion is caused by having too much hydrochloric acid, HC l, in the stomach. Tablets called antacids are used to treat indigestion. One of the chemicals used as an antacid is magnesium hydroxide, Mg(OH) 2. (a) Write a balanced chemical equation to show the reaction between hydrochloric acid and magnesium hydroxide. 2HCl + Mg(OH)2 → MgCl2 + 2 H2O [2] (b) What name is given to this type of reaction? Neutralisation [1]

6 16 29 As temperature increased, the percentage of ammonia decreased. aqueous Mr of (NH4)2SO4 = 2[14+4(1)] + 32 + 4(16) = 132 x

7 17 (a) Name all the three elements present in the fertiliser. Nitrogen, phosphorus, potassium [1] Y Controlling / reducing the acidity of soil They will react to form calcium sulfate, ammonia and water. [1] This will make both fertiliser and calcium hydroxide ineffective [1]

8

9 30 kg of phosphorus gives ideal maximum potato yield. Increasing mass of phosphorus further will not increase the yield as much.

10 Mass of phosphorus in each bag = 4% x 50 kg = 2 kg No. of bags = 30 kg / 2 kg = 15 bags Calcium hydroxide Calcium hydroxide is alkaline / basic and will neturalise the acid in soil.