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MODULE • Chemistry Form 4

3 2.08 g of element X combines with 4.26 g of element Y to form a compound with formula XY . Calculate the relative
3
atomic mass of element X. [RAM: Y = 35.5]
2.08 g unsur X bergabung dengan 4.26 g unsur Y untuk membentuk sebatian dengan formula XY . Hitung jisim atom relatif unsur X.
3
[JAR: Y = 35.5]
Element / Unsur X Y x = relative atomic mass of X
Mass of element (g) 2.08 4.26
Jisim unsur (g) Mol X = 1
Mol Y 3
Number of mole of atoms 2.08 4.26 = 0.12 2.08
Bilangan mol atom x 35.5 x 1
=
Simplest ratio of moles 1 3 0.12 3
Nisbah mol teringkas x = 52

4 2.07 g of element Z reacts with bromine to form 3.67 g of a compound with empirical formula ZBr . Calculate the
2
relative atomic mass of element Z. [RAM: Br = 80]
2.07 g unsur Z bertindak balas dengan bromin membentuk 3.67 g sebatian dengan formula empirik ZBr . Hitung jisim atom relatif bagi
2
unsur Z. [JAR: Br = 80]
Element / Unsur Z Br z = relative atomic mass of Z
Mass of element (g) 2.07 1.6 Mol Z = 1
Jisim unsur (g) Mol Br 2
2.08
Number of mole of atoms 2.07 1.6 = 0.02
Bilangan mol atom z 80 z = 1
0.02 2
Simplest ratio of moles 1 2 z = 207
Nisbah mol teringkas

5 The statement below is about compound J / Pernyataan berikut adalah mengenai sebatian J.

• It is black solid / Merupakan pepejal hitam.
• Contains 12.8 g copper and 0.2 mol of oxygen / Mengandungi 12.8 g kuprum dan 0.2 mol oksigen.
[Relative atomic mass / Jisim atom relatif : Cu = 64]

(a) What is meant by empirical formula / Apakah maksud formula empirik?
A formula that shows the simplest whole number ratio of atoms of each element in a compound.
(b) (i) Calculate the number of mol of copper atom / Hitung bilangan mol atom kuprum.
12.8
= 0.2 mol
64
(ii) What is the empirical formula of compound J / Apakah formula empirik sebatian J ?
0.2 mol Cu : 0.2 mol O.
1 mol Cu : 1 mol O.
Empirical formula of Compound J is CuO.

(c) Compound J reacts completely with hydrogen to produce copper and compound Q.
Sebatian J bertindak balas lengkap dengan hidrogen menghasilkan kuprum dan sebatian Q.
(i) State one observation for the reaction / Nyatakan satu pemerhatian daripada tindak balas tersebut.
Black solid change to brown
(ii) Name two the substances that can be used to prepare hydrogen gas.
Namakan dua bahan yang digunakan untuk menyediakan gas hidrogen.
Zinc/magnesium and hydrochloric acid/nitric acid/sulphuric acid.

(iii) Name compound Q / Nama sebatian Q.
Water
(iv) Write a balanced equation for the reaction.
Tuliskan persamaan kimia yang seimbang bagi tindak balas tersebut.
CuO + H → Cu + H O
2 2
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