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MODULE • Chemistry Form 4

5 The general steps used in any calculation involving neutralisation:
Langkah umum dalam penghitungan yang melibatkan peneutralan:
Step / Langkah 1 : Write the balanced equation / Tulis persamaan yang seimbang.
Step / Langkah 2 : Write the information from the question above the equation.
Tulis maklumat daripada soalan di atas persamaan.
Step / Langkah 3 : Write the information from the chemical equation below the equation (number of moles of substance
involved).
Tulis maklumat daripada persamaan kimia di bawah persamaan (bilangan mol bahan yang terlibat).
Step / Langkah 4 : Change the information to mole / Tukar maklumat kepada mol.
Step / Langkah 5 : Use the relationship between the number of moles of the substances in Step 3.
Guna hubungan di antara bilangan mol bahan-bahan dalam Langkah 3.
Step / Langkah 6 : Convert the number of mol to the required unit with the formula:
Tukar bilangan mol kepada unit yang diperlukan dengan menggunakan formula:

Mv
n = atau n = MV
1 000
n = Number of moles of solute / Bilangan mol bahan terlarut
M = Concentration in mol dm (molarity) / Kepekatan dalam mol dm (kemolaran)
–3
–3
3
V = Volume of solution in dm / Isi padu larutan dalam dm 3
3
v = Volume of solution in cm / Isi padu larutan dalam cm 3

EXERCISE / LATIHAN

3
–3
3
1 50 cm of 1 mol dm sodium hydroxide solution is neutralised by 25 cm of sulphuric acid. Calculate the concentration
of sulphuric acid in mol dm and g dm . [RAM: H = 1, S = 32, O = 16]
–3
–3
–3
3
50 cm larutan natrium hidroksida 1 mol dm dineutralkan oleh 25 cm asid sulfurik. Hitung kepekatan asid sulfurik dalam mol dm dan
–3
3
–3
g dm . [JAR: H = 1, S = 32, O = 16]
–3
M = 1 mol dm M = ? Concentration of H SO = n mol
3
V = 50 cm 3 V = 25 cm 2 4 V dm 3
0.025 mol
2NaOH + H SO Na SO + 2H O = = 1 mol dm –3
2 4 2 4 2 25
1 000 dm 3
Number of mol of NaOH = 1 × 50 = 0.05 mol
1 000 Concentration of H SO
2
4
–3
–1
From the equation, 2 mol of NaOH : 1 mol of H SO 4 = 1 mol dm × (2 × 1 + 32 + 16 × 4) g mol
2
0.05 mol of NaOH : 0.025 mol of H SO = 98 g dm –3
2 4
–3
–3
2 Calculate the volume of 2 mol dm sodium hydroxide needed to neutralise 100 cm of 1 mol dm hydrochloric acid.
3
–3
Hitung isi padu larutan natrium hidroksida 2 mol dm yang diperlukan untuk meneutralkan 100 cm asid hidroklorik 1 mol dm .
3
–3
–3
–3
M = 2 mol dm M = 1 mol dm
3
V = ? cm V = 100 cm
3
NaOH + HCl NaCl + H O
2
100
Number of mol of HCl = 1 × = 0.1 mol
1 000
From the equation, 1 mol of HCl : 1 mol of mol NaOH
0.1 mol of HCl : 0.1 mol of mol NaOH
n mol
Volume of NaOH =
M mol dm –3
0.1 mol
=
2 mol dm –3
= 0.05 dm –3
= 50 cm 3
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