MRSM Pengkalan Chepa Quick revision
-
Upload
austin-cooper -
Category
Documents
-
view
30 -
download
4
description
Transcript of MRSM Pengkalan Chepa Quick revision
![Page 1: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/1.jpg)
MRSM Pengkalan ChepaQuick revisionGive reasons
on form 4 chemistry topics
Name………………………..Class………………
![Page 2: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/2.jpg)
Chapter periodic table
1) K is situated below Na in group 1 elements. Atom K is more reactive than atom Na. Explain ( 3 marks)
Size of K atom is bigger than Na atom .
nuclei attraction ( force of attractions
between nucleus and electrons) in K atom
is weaker than Na atom.
• Potassium atom easier to donate/ release electron to form positive ion .
![Page 3: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/3.jpg)
Chapter periodic table
2) Cl is situated above Br in group 17 elements. Atom Cl is more reactive than Atom Br . Explain ( 3 marks)
Size of Cl atom is smaller than Br atom .
nuclei attraction ( force of attractions
between nucleus and electrons) in Cl atom
is stronger than Br atom.
• Chlorine atom easier to gain electron to form negative ion .
![Page 4: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/4.jpg)
Chapter periodic table3) Ne does not form compound with other atoms.
Explain ( 2 marks) Atom neon has stable electron
arrangement of octet .
So atom neon does not need to gain,
release or share electron with other atoms
Note: Only helium has duplet electron arrangement.
Other atoms in group 18, has octet electon arrangement.
![Page 5: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/5.jpg)
4) Atom X and atom Y are situated in the same period in the periodic table. Which atom is smaller in size? . Explain( 3 marks)
• size of atom Y is smaller than X• number of proton of atom Y is more than atom X• nuclei attraction in atom Y is stronger
![Page 6: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/6.jpg)
5) Sodium and lithium has similar chemical properties. Why?( 1 marks)
• sodium atom and lithium atom has the same number of valence electrons, that is one
![Page 7: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/7.jpg)
6) Fluorine and chlorine has similar chemical properties. Why?( 1 marks)
• Fluorine atom and chlorine atom has the same number of valence electrons, that is seven
![Page 8: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/8.jpg)
Chapter on chemical bonds
7) Covalent compound has low melting point and boiling point. Why?( 2 marks)
• The molecules are held by weak Van de Waals forces of attractions
• So less heat energy is needed to overcome the attraction8) Ionic compound has high melting point and boiling point. Why?( 2 marks)
• The ions are held by strong electrostatic forces of attractions
• So more heat energy is needed to overcome the attraction
![Page 9: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/9.jpg)
Chapter on chemical bonds
9) Covalent compound does not conduct electricity in all states, but ionic compound conduct electricity in molten and aqueous state . Why?( 2 marks)
• Covalent compound consists of molecules and do not contain mobile ions.
• But ionic compound in molten or aqueous state contain mobile ions to conduct electricity
![Page 10: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/10.jpg)
Chapter electrochemistry
10)Electrolysis of copper(II) sulphate solution using carbon electrodes . After one hour, the intensity of blue solution decrease. Explain( 1 marks)
Because the concentration of copper(II) ion decreases OR Copper(II) ions are discharge to copper atoms( Cu 2+ + 2e Cu)
![Page 11: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/11.jpg)
11)Electrolysis of copper(II) sulphate solution using copper electrodes . After one hour, the intensity of blue solution remain the same. Explain( 3 marks)
• Rate of discharge of copper(II) ions at cathode( Cu2+ + 2e Cu)Is equal to• Rate of ionization of copper atoms to copper(II) ions at anode( Cu Cu2+ + 2e)
• Concentration of copper(II) ions remain constant
![Page 12: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/12.jpg)
12) Explain the observation after 30 minutes experiment is carried out. ( 6 marks)
• Copper(II) ions are discharged to form copper atoms ( Cu2+ + 2e Cu)a) Brown deposit on copper metal
b) Zinc electrode becomes thinner
c) Intensity of blue solution decrease
• Zinc atom ionize to form zinc ions ( Zn Zn2+ + 2e)
• Concentration of copper(II) ions decrease /Copper(II) ions are discharged to form copper atoms ( Cu2+ + 2e Cu)
![Page 13: MRSM Pengkalan Chepa Quick revision](https://reader036.fdocuments.in/reader036/viewer/2022082517/56812ad5550346895d8eba37/html5/thumbnails/13.jpg)
13) Diagram above shows neutralization reaction between sulphuric acid and NaOH. In this experiment, 20 cm3 of sulphuric acid needed to neutralize exactly the 25 cm3 alkali , NaOH
The experiment is repeated with 1.0 moldm-3
hydrochloric acid to replace the sulphuric acid . Predict the volume of hydrochloric acid needed to neutralise 25.0 cm3 the sodium hydroxide, NaOH solution. Give your reason.( 2 marks)
40 cm3 , conc of hydrogen ions in HCl is half than conc of hydrogen ions in
sulphuric acid
Replace with hydrochloric acid