1. ENERGY AND CHEMICAL CHANGES

2. Have you noticed that a matter can
change?
There are two types of changes,

physical changes

chemical changes

3. a)
Physical change only involves a change of
physical properties (shape or appearance)
No change in
chemical properties
Small amount of
energy required
Physical
change
Reversible
No new
substances

4.  boiling
water,
 dissolving sugar in water,
 mashing potato
 water cycle.

5. b) Chemical change is a change which produces
substances which have different chemical
properties from the original substances
Change in chemical
properties
A lot of energy
required
Chemical
change
Irreversible
New
substances
are formed

6.  rusting
of iron
 burning of kerosene
 frying egg
 photosynthesis
 raising cake batter
 souring milk

7.  Section
A: potassium iodide and lead(II)nitrate
solution

8.  Section
water
B: Copper(II)sulphate crystals and

9.  Endothermic
reactions

10.  Exothermic
reaction

11.  Aim:
to study exothermic and endothermic
reactions
 Hypothesis: different types of chemical reactions
cause different changes in temperature
 Variables:
constant variables: volume of distilled water
manipulated variable: type of substance
responding variable: final temperature
 Materials and apparatus:sodium hydroxide,
Ammonium chloride, distilled water, test tube,
thermometer, spatula

12. 
Steps:
1. 5cm³ of distilled water was filled into a test tube
2. the initial temperature of distilled water was
recorded.
3. a few sodium hydroxide were added into the test
tube using a spatula.
4. the mixture was stirred until the sodium hydroxide
dissolved.
5. the final temperature was recorded in the table.
6. the outer wall of the test tube was touched.
7. the experiment was repeated using ammonium
chloride powder.

13. 
Reaction of metals with water
the reaction metals with water will produce
hydrogen gas and alkaline solution
metal + water
hydrogen gas + alkaline solution
for example,
sodium + water
hydrogen gas + sodium hydroxide
different metals, give different reaction with water

14. 
Reaction of metals with acids
metals react with acids to produce salt
and hydrogen gas
metal + acid
salt + hydrogen gas
for example,
magnesium + hydrochloric acid
magnesium chloride + hydogen gas

15. 
Results:
Type of
substances
Initial
Final
Change in
Outer
temperature temperature temperature wall of
/ºC
/ºC
/ºC
test tube
Sodium hydroxide 29
crystals with
distilled water
48
19
Hot
Ammonium
29
28
-1
Cold
chloride powder
with distilled
water
 Analysis: 1. sodium hydroxide is the substance that increase the
water temperature because it released heat (exothermic
reaction)
2. ammonium chloride is the substance that decrease the water
temperature and absorbed heat (endothermic reaction)
 Conclusion: Hypothesis is accepted. Different types of chemical
reactions cause different change in temperature.

16.  Reaction
-
of metals with oxygen
Metals produce metal oxide when heated in
oxygen gas
Metal + oxygen
metal oxide
For example,
aluminium + oxygen
aluminium oxide

17. To fix the position of the
potassium manganate (VII)
crystals at its place
To
provide
oxygen

18.  Results:
a)
Aluminium
b) Zinc

19. c)
Copper
d)
Magnesium

20. 
If carbon can remove oxygen from its metal oxide, so
carbon is more reactive than that metal

21.  Results:
Mixture
Observation
Reaction
Carbon +
lead(II)oxide
Mixture glows
(menyala)
yes
Carbon +
aluminium
oxide
No change
no
Carbon + zinc
oxide
Mixture glows slowly
(menyala perlahan)
yes
 Analysis:
 Conclusion:
 Reflection:
Comparison of
reactivity

23.  Importance
of the reactivity series of metals
1. Reaction of a metal
- predict reactions which involve metals
2. Displacement of metal from a solution
3. Displacement of metal from an oxide
4. Extraction of metal using carbon
5. Terminal of a simple cell

24.  Positions
of Metals in the Reactivity Series
and Methods of Extractions
Metal
Increase
in
reactivity
Method of extraction
Potassium
Sodium
Calcium
Magnesium
Aluminium
Electrolysis of the molten ore
•Metals that are more reactive than carbon
•Extracted by flowing of electric current
through the molten metal oxide
CARBON
Zinc
Iron
Tin
Lead
Heating mixtures of ore and carbon
•Metals that are less reactive than carbon
•Heating metal ores with carbon (coke)
Copper
Mercury
Heating ore (metal sulphides) in air
Silver
Gold
Exist as free elements in the ground

25.  Extraction
of Metals from Their Ores
Metal ore
(example: tin and iron)
•Coke (type of
carbon)
•Limestone
(eliminate
impurities to
form slag)
(Carbon
dioxide)
•Tin oxide + carbon
tin + carbon dioxide
•Iron oxide + carbon
iron + carbon dioxide

26. The process of using electrical energy to decompose
a molten or an aqueous (watery) solution of an ionic
compound.
 Electrolysis involves the movement of ions.

Positive
carbon
electrode(+)
Anion
(negative ion)
Cation
(positive ion)
Negative
carbon
electrode(-)

27. •Lead (+) : grey
•Bromine (-) : brown

28. 1. Metals extraction
- Metals that are more reactive
than carbon are extracted
from the ores.

29. 2. Metal purification
- Impure metal is used as the anode while pure
metal used as cathod
- Electrolyte is the salt solution

30. 3. Metal electroplating
- An object can be electroplated with a metal.
- The metal is used as the anode while the
object is used as the cathode.
(ANODE)
(Object to be plated/
CATHODE)

31.  Aim:
to study the electroplating of objects
made of iron with copper
 Hypothesis: copper deposites as a thin layer
on the iron nail
 Variables:
a) Constant variable:
b) Manipulated variable:
c) Responding variable:
 Materials and apparatus:

32. Steps:
1. A beaker was filled with copper(II)sulphate solution.
2. The apparatus for the electrolysis was set up as
shown in diagram.
3. The copper plate was used as the anode whereas
the iron nail was used as the cathode.
4. The switch was turned on and a current of 0.5A
flowed through the circuit for 10 minutes.
5. The switch was turned off and the iron nail was
taken out.
6. Observation of the products at both electrodes were
recorded.


33. (Iron nail)

34.  Results:
Metal
 Analysis:
Observation
 Conclusion: The copper plate becomes thinner
Copper
Iron nail
A brown solid is deposited

35. 
-
-
-
Simple Cell
Consists of two electrodes
(different metals)
The electrolyte can be a salt
solution, a diluted acid or a
diluted alkali.
The more reactive metal
electrode acts as the negative
terminal
The less reactive metal electrode
acts as the positive terminal
Chemical energy to electrical
energy
V

36.  Result:
a)
Zinc and Copper
b) Copper and copper

37.  Dry
-
cell
Easy to carry and supply constant current
Cannot be recharged and not long lasting

38.  Lead-acid
-
accumulator
6 lead-acid cells connected in series
12 V (high voltage)
Car battery (heavy & electrolyte is easy to
spills over )

39.  Alkaline
-
battery
Different electrolyte with dry cell
Long-lasting & higher current than dry cell
Cannot be recharged & expensive

40.  Mercury
-
cell/ zinc-silver oxide battery
1.2 V
Long-lasting & supply constant current
Cannot be recharged

41.  Nickle-cadmium
-
battery
Same principle as an accumulator but uses
different substances
Long-lasting, can be recharged

42.  Example
of chemical reactions which require
light is photosynthesis
 Change light energy to chemical energy

43. Photographic film contains photosensitive coatings
made up of silver bromide.
 Photosensitive substances are substances that
undergo chemical change when exposed to light.


44.  The
silver bromide decomposes to black
silver metal and bromine gas when exposed.
 The exposed area produces opaque area.
 Silver bromide
silver + bromide

45.  Covered
with thumb
 Exposed
to light