Page 131 - Nilam_Publication_module_Chemistry_Form.pdf

Chemistry Form 4 • MODULE

– Dissolve 20.0 g of NaOH in distilled water in a beaker.
Larutkan 20.0 g NaOH dalam air suling di dalam bikar.
3
– Transfer the content into a 500 cm volumetric flask .
3
Pindahkan kandungan ke dalam kelalang volumetrik 500 cm .
– Rinse the beaker with distilled water and transfer all the contents into the volumetric flask .
Bilas bikar dengan air suling dan pindahkan semua kandungan ke dalam kelalang volumetrik .
– Distilled water is added to the volumetric flask until the calibration mark .
Air suling ditambah kepada kelalang volumetrik hingga tanda senggatan .
– The volumetric flask is closed tightly with stopper and inverted a few times to get
homogeneous solution.
Kelalang volumetrik ditutup dengan penutup dan ditelangkupkan beberapa kali untuk mendapatkan larutan
yang homogen.
(ii) Describe how you would prepare 250 cm of 0.1 mol dm sodium hydroxide from the above solution.
–3
3
Huraikan bagaimana anda menyediakan 250 cm larutan natrium hidroksida 0.1 mol dm daripada larutan di atas.
3
–3
Calculate the volume of 1 mol dm sodium hydroxide used:
–3
–3
Hitung isi padu natrium hidroksida 1 mol dm yang digunakan:
– M × V = M × V
1 1 2 2
M × V 0.1 × 250
– V = 2 2 = = 25 cm 3
1
M
1 1
Preparation of 250 cm 1.0 mol dm sodium hydroxide solution:
–3
3
–3
3
Penyediaan 250 cm larutan natrium hidroksida 1.0 mol dm :
– A pipette is filled with 25 cm 3 of 1.0 mol dm sodium hydroxide solution.
–3
Sebuah pipet diisi dengan 25 cm 3 larutan natrium hidroksida 1.0 mol dm .
–3
–3
3
– 25 cm 3 of 1.0 mol dm NaOH is transferred into 250 cm volumetric flask .
3
25 cm 3 NaOH 1.0 mol dm dipindahkan kepada kelalang volumetrik 250 cm .
–3
– Distilled water is added to the volumetric flask until the calibration mark .
Air suling ditambah kepada kelalang volumetrik hingga tanda senggatan .
– The volumetric flask is closed tightly with stopper and inverted a few times to get
homogeneous solution.
Kelalang volumetrik ditutup dengan penutup dan ditelangkupkan beberapa kali untuk mendapatkan larutan
yang homogen.
EXERCISE / LATIHAN

1 The table below shows the pH value of a few substances / Jadual di bawah menunjukkan nilai pH bagi beberapa bahan.
Substance / Bahan pH value / Nilai pH
–3
Ethanoic acid 0.1 mol dm / Asid etanoik 0.1 mol dm –3 3
–3
Hydrochloric acid 0.1 mol dm / Asid hidroklorik 0.1 mol dm –3 1
Glacial ethanoic acid / Asid etanoik glasial 7
(a) (i) What is meant by weak acid and strong acid / Apakah yang dimaksudkan dengan asid lemah dan asid kuat ?

Weak acid / Asid lemah : An acid that partially ionises in water to produce low concentration of hydrogen ion,
+
H .
Strong acid / Asid kuat : An acid that completely ionises in water to produce high concentration of hydrogen
+
ion, H .

129
Nilam Publication Sdn. Bhd.

06-Chem F4 (3P).indd 129 12/9/2011 5:55:56 PM