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MODULE • Chemistry Form 4

7 Compare the number of molecule in 32 g of sulphur dioxide (SO ) with 7 g of nitrogen gas (N ). Explain your answer.
2
2
Bandingkan bilangan molekul dalam 32 g sulfur dioksida (SO ) dengan 7 g gas nitrogen (N ). Terangkan jawapan anda.
2
2
[Relative atomic mass / Jisim atom relatif : S = 32, O = 16, N = 14]
32
Number of moles of molecules in 32 g SO = = 0.5 mol
2 64
7
Number of moles of molecules in 7 g N = = 0.25 mol
2 28
Number of molecule in 32 g SO is two times more than 7 g N .
2
2
Number of mole in sulphur dioxide molecule is two times more than number of mole of nitrogen molecule.
8 Compare number of atoms in 1.28 g of oxygen to the number of atoms in 1.3 g of zinc. Explain your answer.
Bandingkan bilangan atom dalam 1.28 g oksigen dengan bilangan atom dalam 1.3 g zink. Terangkan jawapan anda.
[Relative atomic mass / Jisim atom relatif : O = 16, Zn = 65]
1.28
Number of mol of O atoms in 1.28 g SO = 16 = 0.08 mol
2
1.30
Number of mol of Zn atoms in 1.3 g Zn = = 0.04 mol
65
Number of oxygen atoms in 1.28 g oxygen is 2 times more than number of zinc atoms in 1.3 g zinc.
Number of mol of oxygen atom is 2 times more than zinc atom.

CHEMICAL FORMULAE AND CHEMICAL EQUATIONS / FORMULA KIMIA DAN PERSAMAAN KIMIA

1 Symbol of elements – use capital letters for the first alphabet and use small letters if there is a second alphabet.
Simbol unsur – gunakan huruf besar untuk huruf pertama dan huruf kecil jika ada huruf kedua.
Example / Contoh: Potassium / Kalium – K, Sodium / Natrium – Na
Calcium / Kalsium – Ca, Nitrogen / Nitrogen – N
Iron / Ferum – Fe, Fluorine / Fluorin – F

Chemical Formula – A set of chemical symbols for atoms of elements in whole numbers representing chemical
substances.
Formula kimia – Satu set simbol kimia bagi atom-atom unsur dengan gandaan nombor bulat yang mewakili bahan kimia.
Chemical substance Chemical formula Notes
Bahan kimia Formula kimia Catatan
Water H O 2 atoms of H combines with 1 atom of O.
Air 2 2 atom H bergabung dengan 1 atom O.
Ammonia NH 3 atoms of H combines with 1 atom of N.
Ammonia 3 3 atom H bergabung dengan 1 atom N.
Propane C H 3 atoms of C combines with 8 atoms of H.
Propana 3 8 3 atom C bergabung dengan 8 atom H.

2 Information that can be obtained from the chemical formula / Maklumat yang diperoleh daripada formula kimia:
(i) All the elements present in the compound / Jenis unsur yang terdapat dalam sebatian,
(ii) Number of atoms of each element in the compound / Bilangan atom setiap unsur yang terdapat dalam sebatian,
(iii) Calculation of RMM/RFM of the compound / Pengiraan JMR/JFR bagi sebatian.
3 Two types of chemical formula / Dua jenis formula kimia:
(i) Empirical formula / Formula empirik,
(ii) Molecular formula / Formula molekul.

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