Page 9 - Focus SPM KSSM F4 2020 - Chemistry

Chemistry Form 4 Chapter 3 The Mole Concept, Chemical Formula and Equation
4. The particles referred depends on the type of substance (Table 3.3).
Table 3.3 Type of substance and type of particles

Type of Atomic substance Molecular substance Ionic substance
substance (consists of atoms) (consists of molecules) (consists of ions)

Example of • All metal elements • Most non-metal elements such as All ionic compounds
substances • All noble gases hydrogen (H ), oxygen (O ), nitrogen such as sodium chloride
2
2
• Some non-metal elements (N ), fluorine (F ), chlorine (Cl ), and zinc oxide
2
2
2
such as carbon and silicon bromine (Br ), iodine (I ), sulphur (S )
8
2
2
and phosphorus (P ).
4
• All covalent compounds
The meaning 1 mole of atomic substance 1 mole of molecular substance has 6.02 1 mole of ionic substance
of 1 mole of has 6.02 × 10 atoms. For × 10 molecules. For example, 1 mole has 6.02 × 10 formula
23
23
23
substance example, 1 mole of zinc of oxygen gas contains 6.02 × 10 O units. For example, 1 Chapter
23
2
contains 6.02 × 10 zinc molecules. mole of sodium chloride
23
atoms. contains 6.02 × 10 NaCl
23
3
units.
5. We can calculate the number of particles in a fraction of mole of substance by using the Avogadro’s
constant, N as follows. (N : 6.02 × 10 mol )
23
-1
A A
Number × N A Number of
of moles ÷ N particles
A
EXAMPLE 3.4
Calculate the number of atoms in:
1. 0.5 mole of copper
2. 2 moles of hydrogen gas
Solution
1. Copper is an atomic substance.
So, 1 mole of copper has 6.02 × 10 of copper atoms.
23
The number atoms in 0.5 mole of copper
= Number of mole × N A
= 0.5 × 6.02 × 10 atoms
23
= 3.01 × 10 atoms
23
2. Hydrogen gas is a molecular substance.
So, 1 mole of hydrogen gas has 6.02 × 10 H molecules.
23
2
The number of H molecules in 2 moles of hydrogen gas
2
= number of mole × N A
= 2 × 6.02 × 10 H molecules
23
2
Based on the formula H , each H molecule is made up of 2 H atoms.
2
2
Therefore, the number of H atoms in 2 moles of hydrogen gas
23
= 2 × 2 × 6.02 × 10 atoms
= 24.08 × 10 atoms
23
= 2.408 × 10 atoms
24
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03 SPM CHEMISTRY F4.indd 37 27/02/2020 11:23 AM

Bilangan mol ÷ N A Bilangan zarah
x N
A