Page 4 - 1202 Question Bank Chemistry Form 5 KSSM

KNOW Important Definitions

Thermoplastic, Thermosetting and Elastomer Types of Chemical Reaction

• Thermoplastics are loose polymer that can be heated and Exothermic reaction:
reshaped repeatedly.
©PAN ASIA PUBLICATIONS
• Chemical reaction that releases heat energy to the surroundings.
• Thermosettings are rigid polymer that will not return to • Temperature of the surroundings increases.
their original shape when heated.

• Elastomers are polymer that can be deformed and returned Endothermic reaction:
to their original shape. • Chemical reaction that absorbed heat energy from the
surroundings.
• Temperature of the surroundings decreases.

Important Definitions (Chapter 4) 20 @ Pan Asia Publications Sdn. Bhd. Important Definitions (Chapter 3) 14 @ Pan Asia Publications Sdn. Bhd.

Soap and Detergent Heat of Displacement

• Soaps are sodium or potassium salts of fatty acids. • Heat of displacement is the heat change when one mole of
a metal is displaced from its aqueous salt solution by a more
• Detergents are sodium salts of sulphonic acids or alkyl electropositive metal.
hydrogen sulphates.
Q
• Heat of displacement = −
• Saponification is the process to prepare soaps by alkaline n
hydrolysis of fats or oils.
Heat change,
Q = mcθ
Fats or oils Fatty acid + Glycerol = V × 4.2 J g °C × θ
−1
−1
Precipitation Number of moles,
Fatty acid salt (soap) MV
n =
1 000

Important Definitions (Chapter 5) 22 @ Pan Asia Publications Sdn. Bhd. Important Definitions (Chapter 3) 16 @ Pan Asia Publications Sdn. Bhd.

• Nanoscience is a study on processing of substances at Heat of Combustion
nanoscale, between 1 nanometre - 100 nanometres.

• Nanotechnology is the study and manipulation of matter at • Heat of combustion is the total heat released when one mole of
nanometer scale to produce new materials or devices. fuel is burnt completely in excess oxygen gas.
−1
• Graphene is the carbon allotrope. Graphene is one-layer thick • Heat of combustion is given in the unit kJ mol .
graphite arranged in hexagonal honeycomb-like structure to
Q
form graphene sheets. • Heat of combustion = −
n
• Graphene sheets can used to produce graphites, carbon Heat change,
nanotubes and fullerene balls. Q = mcθ
−1
−1
= V × 4.2 J g °C × θ
Number of moles,
Mass
n =
Molar mass

Important Definitions (Chapter 5) 24 @ Pan Asia Publications Sdn. Bhd. Important Definitions (Chapter 3) 18 @ Pan Asia Publications Sdn. Bhd.