TB solution 1B(Topic 4&5).doc - Topic 4 Unit 13 Suggested...

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Topic 4 Unit 13Suggested answers to in-text activitiesLibrary Search (page 2)Some possible items are listed in the table below.Household itemAcid it containsCitrus fruitsCitric acidTomato sauceEthanoic acidSoft drinkCarbonic acidKettle cleanerMethanoic acidCar batterySulphuric acidToliet bowl cleanerHydrochloric acidDiscussion (page 8)1Test whether the colourless solution shows the typical properties of an acid.2a)Baking powder is a mixture of sodium hydrogencarbonate and a solid acid.b)Water and a little baking powder are added to flour when making cakes. The cake mixture is then heated in an oven.When sodium hydrogencarbonate is heated, it decomposes to give carbon dioxide gas:2NaHCO3(s) Na2CO3(s) + CO2(g) + H2O(l)The solid acid in the powder gives hydrogen ions when dissolved in water. Carbon dioxide gas is also liberated by the action of hydrogen ions on sodium hydrogencarbonate. The carbon dioxide makes the cake ‘rise’.Check Your Understanding (page 16)1Gas bubbles are given off.Fe(s) + 2H+(aq) Fe2+(aq) + H2(g)2Effervescence occurs.CO32-aq) + 2H+(aq) CO2(g) + H2O(l)3A pale blue precipitate forms.Cu2+(aq) + 2OH-(aq) Cu(OH)2(s)Problem Solving (page 16)1
-First add sodium carbonate solid to the reagents. Effervescence will occur for dilute sulphuric acid.-Then add copper(II) chloride solution to the remaining three reagents. Both ammonia solution and dilute sodium hydroxide solution will give a pale blue precipitate. However, the pale blue precipitate will redissolve in excess ammonia solution.-The remaining reagent is distilled water.Internet Search and Presentation (page 18)Concentrated hydrochloric acidHazard warning symbolRisk descriptionsCauses burns Irritating to respiratory systemSafety precautionsIn case of contact with eyes, rinse immediately with pkenty of water and seek medical advice.In case of accident and if you feel unwell, seek medical immediately.Concentrated nitric acidHazard warning symbolRisk descriptionsCauses severe burnsContact with combustible material may cause fireSafety precautionsDo not inhale fumes / vapour / spray.In case of contact with eyes, rinse immediately with pkenty of water and seek medical advice.In case of accident and if you feel unwell, seek medical immediately.Concentrated sulphuric acidHazard warning symbolRisk descriptionsReacts violently with waterCauses severe burnsIrritating to respiratory systemSafety precautionsNever add water to concentrated sulphuric acid.In case of contact with eyes, rinse immediately with pkenty of water and seek medical advice.In case of accident and if you feel unwell, seek medical immediately.Hazard warning symbol2
Concentrated sodiumhydroxide solutionRisk descriptionsCauses severe burnsSafety precautionsWear protective gloves and eye/face protection.

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