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MODULE • Chemistry Form 4

8 Calculate the volume of nitric acid, 1 mol dm needed to be diluted by distilled water to obtain 500 cm of nitric acid,
3
–3
0.1 mol dm .
–3
–3
3
Hitung isi padu asid nitrik 1 mol dm yang diperlukan untuk dilarutkan oleh air suling bagi menghasilkan 500 cm asid nitrik 0.1 mol dm .
–3

Answer / Jawapan : 50 cm 3
3
3
–3
+
9 (a) Compare the number of mol of H ions which are present in 50 cm of 1 mol dm of sulphuric acid and 50 cm of
1 mol dm of hydrochloric acid. Explain your answer.
–3
–3
3
–3
+
3
Bandingkan bilangan mol ion H yang hadir dalam 50 cm asid sulfurik 1 mol dm dengan 50 cm asid hidroklorik 1 mol dm .
Terangkan jawapan anda.
–3
Acid 50 cm of 1 mol dm of sulphuric acid 50 cm of 1 mol dm of hydrochloric acid
3
–3
3
3
3
Asid 50 cm asid sulfurik 1 mol dm –3 50 cm asid hidroklorik 1 mol dm –3
Calculate number of 50 × 1 50 × 1
hydrogen ion, H + Number of mol of sulphuric acid = 1 000 Number of mol of hydrochloric acid = 1 000
Hitung bilangan mol = 0.05 mol = 0.05 mol
ion hidrogen, H +
H SO 2H + SO 2– HCl H + Cl –
+
+
2 4 4
From the equation, From the equation,
+
1 mol of H SO : 2 mol of H 1 mol of HCl : 1 mol of H
+
2 4
0.05 mol of H SO : 0.1 mol of H + 0.05 mol of HCl : 0.05 mol of H +
2 4
–3
+
Compare the number The number of H in 50 cm of 1 mol dm of sulphuric acid is twice of the number of H in
3
+
of hydrogen ions 50 cm of 1 mol dm of hydrochloric acid.
–3
3
Bandingkan bilangan
ion hidrogen
Explanation Sulphuric acid is diprotic acid whereas hydrochloric acid is monoprotic acid.
Penerangan 1 mol of sulphuric ionises to 2 mol of H whereas 1 mol of hydrochloric acid ionises to 1 mol of H .
+
+
The number of H in the same volume and concentration of both acids is doubled in sulphuric acid
+
compared to hydrochloric acid.
(b) Suggest the volume of 1 mol dm of hydrochloric acid that has the same number of H with 50 cm of 1 mol dm
–3
+
3
–3
of sulphuric acid.
Cadangkan isi padu asid hidroklorik 1 mol dm yang mempunyai bilangan ion H yang sama dengan 50 cm asid sulfurik 1 mol dm .
+
3
–3
–3
100 cm 3
NEUTRALISATION / PENEUTRALAN
1 Neutralisation is the reaction between an acid and a base to form only salt and water:
Peneutralan ialah tindak balas antara asid dan bes untuk membentuk garam dan air sahaja:
Acid / Asid + Base / Bes Salt / Garam + Water / Air

Example / Contoh :
HCl (aq/ak) + NaOH (aq/ak) NaCl (aq/ak) + H O (l/ce)
2
2HNO (aq/ak) + MgO (s/p) Mg(NO ) (aq/ak) + H O (l/ce)
2
3 2
3
2 In neutralisation, the acidity of an acid is neutralised by an alkali. At the same time the alkalinity of an alkali is
neutralised by an acid. The hydrogen ions in the acid react with hydroxide ions in the alkali to produce water:
Dalam peneutralan, keasidan asid dineutralkan oleh alkali. Pada masa yang sama, kealkalian alkali dineutralkan oleh asid. Ion hidrogen
dalam asid bertindak balas dengan ion hidroksida dalam alkali:
+
H (aq/ak) + OH (aq/ak) H O (l/ce)
–
2
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