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Chemistry Form 4 • MODULE

8 The diagram below shows the formation of zinc nitrate and the changes to other compounds.
Rajah berikut menunjukkan pembentukan zink nitrat dan perubahannya kepada sebatian lain.
+ Substance X Heat
Zinc oxide + Bahan X Zinc nitrate Panaskan Brown gas
Zink oksida Zink nitrat Gas perang

+ Potassium carbonate solution/ + Larutan kalium karbonat

Precipitate Z + Potassium nitrate
Mendakan Z Kalium nitrat

(a) (i) Zinc oxide reacts with substance X to form zinc nitrate. State the name of substance X.
Zink oksida bertindak balas dengan bahan X untuk membentuk zink nitrat. Namakan sebatian X.

Nitric acid
(ii) Write the chemical equation for the reaction in (a)(i).
Tuliskan persamaan kimia untuk tindak balas dalam (a)(i).
ZnO + HNO → Zn(NO ) + H O
3 3 2 2
(b) (i) State the name of the brown gas formed.
Namakan gas perang yang terbentuk.
Nitrogen dioxide
(ii) Write the chemical equation for the reaction in (b)(i).
Tuliskan persamaan kimia untuk tindak balas dalam (b)(i).
2Zn(NO ) → 2ZnO + 2NO + O
3 2 2 2
(c) When potassium carbonate solution added to zinc nitrate solution, precipitate Z and potassium nitrate formed.
Apabila larutan kalium karbonat ditambah kepada larutan zink nitrat, mendakan Z dan kalium nitrat terbentuk.
(i) State the type of reaction occurs.
Namakan jenis tindak balas yang berlaku.
Precipitation

(ii) Write the ionic equation for the formation of compound Z.
Tulis persamaan ion untuk pembentukan sebatian Z.
Zn + CO → ZnCO
2+
2–
3 3
(iii) State how the precipitate Z separated from potassium nitrate.
Nyatakan bagaimana mendakan Z diasingkan daripada kalium nitrat.
Filtration
–3
3
(d) Excess of zinc nitrate solution is added to 100 cm of 1 mol dm potassium carbonate. Calculate the mass of zinc
carbonate formed. [Relative atomic mass: Zn = 65, C = 12, O = 16]
Larutan zink nitrat berlebihan ditambah kepada 100 cm larutan kalium karbonat 1 mol dm . Hitungkan jisim zink karbonat yang
–3
3
terbentuk. [Jisim atom relatif: Zn = 65, C = 12, O = 16]
Zn(NO ) + K CO → ZnCO + 2KNO
3 2 2 3 3 3
100
Mol of K CO = 1× = 0.1 mol
2 3 1 000
From the equation, 1 mol K CO : 1 mol ZnCO 3
3
2
0.1 mol K CO : 0.1 mol ZnCO
2 3 3
Mass of ZnCO = 0.1 mol × 125 g mol = 12.5 g
–1
3
(e) Sodium hydroxide solution is added until excess to zinc nitrate solution. State the observation that can be made.
Larutan natrium hidroksida ditambah sedikit demi sedikit hingga berlebihan kepada larutan zink nitrat. Nyatakan pemerhatian yang
dapat dibuat.
White precipitate soluble in excess of sodium hydroxide solution.
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