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MODULE • Chemistry Form 4

3 The constant temperature at which a solid completely changes to become a liquid is called the melting point .
During the melting process, the temperature remains unchanged because heat energy absorbed by the particles
is used to overcome the forces between particles so that the solid change to turn into a liquid .
Suhu tetap di mana suatu pepejal berubah kepada keadaan cecair dipanggil takat lebur .
Semasa proses peleburan, suhu tidak berubah kerana haba yang diserap oleh zarah-zarah digunakan untuk
mengatasi daya tarikan antara zarah supaya pepejal berubah menjadi cecair .
4 The constant temperature at which a liquid completely changes to become a gas is called the boiling point .
During the boiling process, the temperature remains unchanged because heat energy absorbed by the particles
is used to overcome the forces between particles so that the liquid change to turn into a gas.
Suhu tetap di mana suatu bahan dalam keadaan cecair berubah kepada keadaan gas dipanggil takat didih .
Semasa proses pendidihan, suhu tidak berubah kerana haba yang diserap oleh zarah-zarah digunakan untuk
mengatasi daya tarikan antara zarah supaya cecair berubah menjadi gas.

The Explanation for the Cooling Process of Matter: / Penerangan Proses Penyejukan Bahan:

1 The cooling curve of naphthalene:
Lengkung penyejukan naftalena:
Temperature/°C
Suhu/°C

P

Q R

S
Time/s
Masa/s
2 When the liquid is cooled, the particles in the liquid release energy and move slower as its energy content
decreases. As the energy is released to the surrounding, the state of matter will change.
Apabila cecair disejukkan, zarah cecair membebaskan tenaga dan bergerak semakin perlahan. Keadaan jirim
berubah semasa tenaga dibebaskan ke persekitaran.
Point State of matter Explanation
Titik Keadaan jirim Penerangan
Heat is released/given out to the surrounding by the particles in the liquid naphthalene.
The particles in the liquid lose their kinetic energy and move slower. The
P to Q Liquid decreases
P ke Q temperature .
Haba dibebaskan ke persekitaran oleh zarah-zarah dalam cecair naftalena. Zarah-zarah dalam
cecair kehilangan tenaga kinetik dan bergerak semakin perlahan. Suhu semakin menurun .

The heat released to the surrounding by the particles in liquid naphthalene is balanced
by the heat energy released as the particles attract one another to form a solid .
Q to R Liquid and The temperature remains constant .
Q ke R Solid
Haba dibebaskan ke persekitaran oleh zarah-zarah dalam cecair naftalena diimbangi oleh
tenaga haba yang terbebas apabila zarah-zarah tertarik antara satu sama lain untuk membentuk
pepejal . Suhu adalah tetap .
The particles in the solid naphthalene releases heat and vibrate slower . The temperature
R to S Solid decreases .
R ke S Zarah-zarah dalam pepejal naftalena membebaskan tenaga dan bergetar dengan lebih perlahan .
Suhu semakin menurun .

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