: RATE OF REACTION (SECTION B)
SET 3 : RATE OF REACTION (SECTION B)
3. (a) Smaller pieces of wood burn faster compare to bigger pieces of wood. Explain why . Kayu bersaiz kecil terbakar lebih cepat berbanding kayu bersaiz besar. Terangkan mengapa [2 marks]
(b) A student carried out two experiment to investigate the decomposition of hydrogen peroxide. Diagram 3.1 shows the apparatus set-up and observation when a glowing wooden splinter is placed at the mouth of each test tubes of both experiments.
Seorang pelajar menjalankan dua eksperimen untuk mengkaji kesan mangkin mangan (IV) oksida ke atas kadar penguraian hidrogen peroksida. Rajah
3.1 menunjukkan susunan radas dan pemerhatian apabila kayu uji berbara diletakkan pada mulut setiap tabung uji di kedua-Eksperimen
I dan Eksperimen II.
Experiment [Eksperimen] Observation [Pemerhatian] Experiment I
Eksperimen I The wooden splinter glows dimly and
Wooden splinter
Kayu uji berbara Kayu uji
slowly.
Kayu uji berbara akan menyala malap
menyala
dan perlahan.
5 cm 3 of 20-volume of hydrogen No effervescence occurs. peroxide solution. Tiada pembuakan berlaku.
5 cm 3 larutan hidrogen peroksida
20-isipadu.
Experiment II
Eksperimen II The wooden splinter lighted brightly.
Wooden splinter Kayu uji
Kayu uji berbara akan menyala
menyala
Kayu uji berbara
terang.
5 cm of 20-volume of hydrogen
peroxide solution Effervescence occurs.
5 cm 3 larutan hidrogen peroksida
Pembuakan berlaku.
20-isipadu
Catalyst X Mangkin X
Diagram 3.1/ Rajah 3.1
Based on Diagram 3.1 : Berdasarkan Rajah
(i) Identify which experiment has a higher rate of reaction. Give a reason to your answer Kenal pasti eksperimen yang mempunyai mempunyai kadar tindak balas yang tinggi. Berikan
alasan kepada jawapan anda
[2 marks] (ii)
Write a chemical equation to represent the decomposition of hydrogen peroxide.
Tuliskan persamaan kimia bagi penguraian hidrogen peroksida.
[2 marks]
(iii) Draw an energy profile diagram for the decomposition of hydrogen peroxide in Experiment I. Label the activation energy Lukis satu gambar rajah profil tenaga untuk penguraian hidrogen peroksida dalam Eksperimen
I. Label tenaga pengaktifan.
[3 marks]
(c) Diagram 3.2 shows Curve I and Curve II obtained from an experiment using zinc and hydrochloric acid.
Rajah
3.2 menunjukkan Lengkung I dan Lengkung II yang diperolehi daripada suatu eksperimen apabila zink bertindak balas dengan asid hidroklorik
Volume of hydrogen gas/cm 3
Isi padu gas hidrogen /cm 3
Curve I
Curve II
Time/s Masa/s
Diagram 3.2
(i)
Write the chemical equation for the reaction between zinc and hydrochloric acid . Tuliskan persamaan kimia bagi tindak balas di antara zink dan asid hidroklorik.
[2 marks]
3 (ii) -3 Curve I obtained from the reaction between excess zinc powder and 50 cm of 0.5 mol dm hydrochloric acid
3 Lengkung -3 I diperolehi daripada tindak balas antara 50 cm asid hidroklorik 0.5 mol dm . Calculate the maximum volume of gas released
3 -1 [Molar volume: 24 dm mol at room condition] Kirakan isi padu maksimum gas yang terbebas.
-1 [Isi padu molar gas pada keadaan bilik = 24 dm mol ] [3 marks]
(iii) Describe briefly how to obtain curve II Huraikan dengan ringkas bagaimana mendapatkan lengkung II [2 marks]
3 (iv) -3 The experiment is repeated using excess powder and 50 cm of 0.5 mol dm sulphuric acid to
3 replace excess zinc powder and 50 cm -3 of 0.5 mol dm .hydrochloric acid. Explain the rate of reaction and maximum volume of gas collected.
Eksperimen itu diulangi menggunakan serbuk zink berlebihan dan 3 50 cm asid hidroklorik 0.5 mol
3 dm -3 bagi menggantikan serbuk zink berlebihan dengan 50 cm asid hidroklorik 0.5 mol dm . Terangkan kadar tindak balas dan isi padu maksimum gas yang dikumpulkan.
[4 marks]
4. (a) Food in refrigerator last longer compared to food kept in kitchen cabinet at room temperature. Explain why? Makanan disimpan dalam peti sejuk lebih tahan lama berbanding makanan disimpan dalam kabinet dapur pada suhu bilik. Terangkan mengapa?
[3 marks]
(b) Experiment I, II and III are carried out to investigate the factors affecting the rate of reaction between
sulphuric acid and zinc. Diagram 4 shows the results of the Experiment I, II and III Eksperimen
I, II dan III dijalankan untuk mengkaji faktor-faktor yang mempengaruhi kadar tindak balas di antara asid sulfurik dan zink. Rajah 4 menunjukkan keputusan bagi Eksperimen I, II dan III tersebut.
Experiment
I II III Eksperimen
3 50 cm -3 of 1.0 mol dm 50 cm of 1.0 mol dm 50 cm of 0.5 mol dm sulphuric acid
3 -3
3 -3
sulphuric acid
sulphuric acid
3 3 50 cm 3 asid sulfurik 1.0 mol 50 cm asid sulfurik 1.0 mol 50 cm asid sulfurik
Hydrogen gas Gas hidrogen
Hydrogen gas Hydrogen gas
Gas hidrogen Set-up of
Gas hidrogen
apparatus Susunan radas
Zinc granules Serbuk zink
Zinc powder