Page 46 - ACE YR IGCSE A TOP APPROACH TO CHEM

All nitrate compounds are soluble. Bubbles formed in ammonium chloride / gases
All sodium compounds are soluble. formed in ammonium chloride turns the damp
or red litmus paper blue. [1]
Any aqueous solution containing both lead Ammonia gas is produced.
ions and iodide ions. [1] (e) Add sodium hydroxide [1]
An aqueous solution is used to make a precipitate. A blue precipitate is formed for copper(II)
(b) Mix the two aqueous solutions [1] bromide [1]
Filter [1] Copper(II) hydroxide is a blue solid.
A precipitate will be collected in a filter paper. or
Rinse [1] flame test [1]
Rinse it with water to ensure a pure salt is obtained. Lithium gives a red flame. / Copper gives a
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blue-green flame. [1]
Dry with an oven [1]
The drying step must be handled carefully to avoid 9 (a) A [1]
overheating. Dilute hydrochloric acid [1]
Hydrochloric acid contains chloride ions.
(c) Pb + 2I ➞ PbI 2 Zinc carbonate + hydrochloric acid ➞ zinc
–
2+
Correct formula [1] chloride + carbon dioxide + water [1]
Balanced equation [1]
(b) C [1]
(d) Spectator ions [1]
Sodium bromide [1]
(e) Will decompose [1] All sodium compounds are soluble.
7 (a) Silver nitrate [1] Pb + 2Br [1]
–
2+
All nitrate compounds are soluble.
(c) B [1]
Potassium bromide [1] Dilute sulfuric acid [1]
Bromide ions must be present to form silver Sulfuric acid contains sulfate ions.
bromide.
2KOH + H SO ➞ K SO + 2H O
2
4
+
–
(b) Ag (aq) + Br (aq) ➞ AgBr(s) Correct formula 2 4 2 [1]
All the formulas of ions and compound are Balanced equation [1]
correct. [1]
All state symbols are correct. [1] 10 (a) Proton donor [1]
completely dissociated in aqueous solution. [1]
(c) Potassium ion [1]
and nitrate ion [1] (b) (i) Barium sulfate [1]
2+
2–
(d) Silver chloride is insoluble. [1] (ii) Ba + SO ➞ BaSO [1]
4
4
(e) Making coloured pigment for paints / Removal (c) (i) Sulfuric acid + sodium hydroxide ➞
of harmful substances when cleaning up waste sodium sulfate + water [1]
–
+
water. [1] (ii) H + OH ➞ H O [1]
2
8 (a) Lighted splint [1] (d) (i) lithium sulfate + water [1]
Oxygen makes the flame burn brighter. / (ii) zinc sulfate + hydrogen [1]
Hydrogen makes a ‘pop’ sound. [1] (iii) copper(II) sulfate + carbon dioxide + water
(b) Add barium chloride [1] [1]
A white precipitate is formed with zinc sulfate.
[1] 8 The Periodic Table
Barium sulfate is a white solid.
or Part 1: Multiple-choice Questions
Dilute sodium hydroxide and aluminium foil 1 A
and heat [1] The most significant differences between metals and
Zinc nitrate turns the damp red litmus paper transition metals are:
blue. [1] Transition metals have variable oxidation states.
Ammonia gas is produced. Transition metals form coloured compounds.
Transition metals can act as catalysts.
(c) Use damp litmus paper [1] Transition metals form complex ions.
Sulfur dioxide bleaches the litmus paper. [1]
Sulfur dioxide is a bleach. 2 B
As going down Group I, reactivity increases.
(d) Add sodium hydroxide [1] As going down Group VII, reactivity decreases.

Cambridge IGCSE TM
158 Ace Your Chemistry

Answers.indd 158 3/4/22 3:54 PM