Page 31 - Nilam_Publication_module_Chemistry_Form.pdf

Chemistry Form 4 • MODULE

3 (a) Calculate the number of atoms in the following substances / Hitungkan bilangan atom yang terdapat dalam bahan berikut:
23
[Relative atomic mass: N = 14; Zn = 65; Avogadro Constant = 6.02 × 10 ]
[Jisim atom relatif: N = 14; Zn = 65; Pemalar Avogadro = 6.02 × 10 ]
23
(i) 13 g of zinc / 13 g zink
13
Number of mol of zinc atom = = 0.2 mol
65
Number of zinc atom = 0.2 × 6.02 × 10 23
= 1.204 × 10 23

(ii) 5.6 g of nitrogen gas / 5.6 g gas nitrogen
5.6
Number of mol of N atom = = 0.4 mol
14
Number of N atom = 0.4 × 6.02 × 10 23
= 2.408 × 10 23

(b) Calculate the number of molecules in the following substances / Hitungkan bilangan molekul dalam bahan berikut:
[Relative atomic mass: N = 14, H = 1, Cl = 35.5, Avogadro Constant = 6.02 × 10 ]
23
[Jisim atom relatif: N = 14, H = 1, Cl = 35.5, Pemalar Avogadro = 6.02 × 10 ]
23
(i) 8.5 g of ammonia gas, NH / 8.5 g gas ammonia, NH 3
3
8.5
× 6.02 × 10 23
17
= 2.408 × 10 23

(ii) 14.2 g of chlorine gas, Cl / 14.2 g gas klorin, Cl 2
2
14.2
× 6.02 × 10 23
71
= 1.2 × 10 23

4 A gas jar contains 240 cm of carbon dioxide gas. Calculate:
3
3
Suatu balang gas berisi 240 cm gas karbon dioksida. Hitungkan:
[Relative atomic mass: C = 12, O = 16; Molar volume of gas = 24 dm mol at room conditions]
3
–1
[Jisim atom relatif: C = 12, O = 16; Isi padu molar gas: 24 dm mol pada keadaan bilik]
–1
3
(a) Number of moles of carbon dioxide gas / Bilangan mol gas karbon dioksida:
240
Number of moles of CO = = 0.01 mol
2
24 000
(b) Number of molecules of carbon dioxide gas / Bilangan molekul gas karbon dioksida:
Number of molecules of CO = 0.01 × 6.02 × 10
23
2
= 6.02 × 10 21
(c) Mass of carbon dioxide gas / Jisim gas karbon dioksida:
Mass of CO = 0.01 mol × [12 + 2 × 16] g mol
–1
2
= 0.44 g
5 What is the mass of chlorine molecules (Cl ) that contains twice as many molecules as that found in 3.6 g of water?
2
Berapakah jisim molekul klorin (Cl ) yang mengandungi dua kali ganda bilangan molekul yang terdapat dalam 3.6 g air?
2
[Relative atomic mass / Jisim atom relatif : H = 1, O = 16, Cl = 35.5]
Number of moles of chlorine molecule = 2 × no of mol in H O
2
3.6
= 2 × = 0.4 mol
18
Mass of Cl = 0.4 × 71= 28.4 g
2
6 Calculate the mass of carbon that has the same number of atoms as found in 4 g of magnesium.
Hitungkan jisim karbon yang mempunyai bilangan atom yang sama seperti yang terdapat dalam 4 g magnesium.
[Relative atomic mass / Jisim atom relatif : C = 12, Mg = 24]
2 g

29
Nilam Publication Sdn. Bhd.

02-Chem F4 (3P).indd 29 12/9/2011 5:59:06 PM