Page 73 - Chemistry_Form_2

Chemistry
for Secondary Schools

Exercise 3.4

1. A compound has 1.121 g of nitrogen, 0.161 g of hydrogen, 0.480 g of
carbon and 0.640 g of oxygen. Deduce its empirical formula.

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2. A compound has an empirical formula CH. If it has a relative molecular
mass of 78.11, deduce its molecular formula.

3. A compound is analysed and found to contain 52.17% carbon, 13.04%
hydrogen, and 34.78% oxygen. Determine its
(a) empirical formula.

(b) molecular formula, if its relative molecular mass is 46.

Nomenclature of binary inorganic compounds
Everything in the universe bears a name to differentiate it from others. Chemical
substances also bear names that range from those of elements to those of
compounds. The name of a substance can originate from some factors such as
the place of origin, founder, use, and type or classification. Items or substances
that fall under a particular group or classification are named systematically. A
systematic way of assigning names to items that belong to a particular group or
classification is called nomenclature.

Scientists use IUPAC nomenclature in naming chemical compounds so that
experts and other interested persons around the world understand exactly what
the substance is. IUPAC stands for International Union of Pure and Applied
Chemistry.

Binary inorganic compounds

While an inorganic compound is any substance in which two or more chemical
elements (usually other than carbon) are combined, always in definite proportions,
a binary compound is the one which is formed by two chemical substances.
Examples of binary inorganic compounds are CaO, NaCl, and PCl .
3
Inorganic compounds are categorised into ionic and covalent. The nomenclature
of ionic compounds differs slightly from that of covalent compounds.

66 Student’s Book Form Two

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CHEMISTRY FORM TWO NEW 2025 DUMMY.indd 66 01/08/2025 11:20:56