for form five chemistry revision SPM

1. Exp Reactants Products Observation
I
2.6 g of zinc and
50 cm3
of acid P
2.0 mol dm-3
Zinc chloride
and hydrogen
gas
The
temperature
of the mixture
increases
II
2.6 g of zinc and
50 cm3
of acid Q
2.0 mol dm-3
Zinc sulphate
and hydrogen
gas
The
temperature
of the mixture
increases
data from Exp I and Exp II that were carried out to study
the rate of reaction of zinc with two acids, P and Q.
QUESTION 1- RATE OF REACTION

2. • (i) By choosing either
Experiment I or Experiment II, state
the name of the acid used.
•

3. • (i) Write the chemical equation
for the reaction of this acid with
zinc. [2 marks]

4. (ii) Draw an energy profile diagram for
the reaction in 10(a)(i). On the energy
profile diagram show the:
–Heat of reaction, AH
–Activation energy without a catalyst,
–Activation energy with a catalyst, E'
Explain the energy profile diagram.
[10 marks]

5. ∆H
E- activattion energy
without catalyst
E’- activattion
energy with catalyst
energy
Energy profile diagram of reaction
zinc and hydrochloric acid

6. (ii) Explain the energy profile diagram.
∆H

7. (ii) Explain the energy profile diagram.
∆H

8. (ii) Explain the energy profile diagram.
∆H
∆H

9. (ii) Explain the energy profile diagram.
∆H

10. (ii) Explain the energy profile diagram.
∆H

11. What is the function of these food additives?
a) Colouring agents
b) preservatives
c) Anti oxidants
d) Flavouring agents
e) Stabilisers and
thickeners
a) To restore the colour of
original food
b) To destroy or prevent growth
of micro organisms in food
c) To prevention oxidation of
food by air
d) To to give or enhance the
flavour of food
e) To prevent food such as ice
cream from separating into layers
and to thicken soup or gravy
Question no. 2) consumer

12. What type of food additives?
Colouring agents
preservatives
Anti oxidants
Flavouring agents
Stabilisers and thickeners
a) Benzoic acid
b) Pectin
c) Saccharin
d) aspartam
e) Ascorbic acid
Flavouring agents
f) tartrazine
f) Sodium nitrite preservatives

13. What type of food additives?
Colouring agents
preservatives
Anti oxidants
Stabilisers and thickeners
a) Azo compound
b) Vitamin E
c) Mono sodium glutamate
d) agar-agar
e) Gelatin
Flavouring agents
f) Sodium benzoate
Stabilisers and thickeners
g) Sulphur dioxide preservatives

14. What is the function of these traditional medicines?
a) lime
b) garlic
c) ginger
d) onions
e) Betel leaves-
daun sireh
a) To increase digestive juice
b) Has antibiotic property
c) To warm the body
d) To purift blood
e) Stop bleeding nose

15. What is the function of these modern medicines?
a) analgesics
b) antibiotics
c)
Psychotherapeutic
medicines
a) To relieve pain without affecting
consciousness
b) Kill bacteria
c) To treat
mental illness

16. a) stimulants
b) Anti
depressant
c) Antipsychotic
drug
a) To stimulate mental activity
b) To control worry,
fear, anxiety, panic
c) To treat
psychotic illness or
schizophrenia
c) Psychotherapeutic medicines

17. What type of modern medicines?
analgesics
Anti biotics
a) aspirin
b) Penicillin
c) streptomycin
d) Para cetamol
e) caffeine
f) codeine
g) barbiturate
Anti biotics
analgesics
stimulant
analgesics
antidepressant
h) tranquiliser antidepressant

18. What is the uses of modern medicines?
Fever, prevent heart
attack
fever
a) aspirin
b) Penicillin
c) streptomycin
d) Para cetamol
f) codeine
pneumonia Tuberculosis,
dysentry
Treat gonorrhea, syphlis,
pneumonia, meningitis
Cough medicine,
headache

19. Soap:
RCOO –
Na +
or R COO –
K +
Detergent:
What is general formula for
soap?
and detergent?

20. What does hard water contains?
•Hard water contains
calcium ion, Ca2+
or
magnesium ion, Mg2+.

21. Why do soaps form scum with
hard water?
• Soap reacts with calcium
ion, Ca2+
or magnesium ion,
Mg2+
in hard water to form
insoluble salt, called scum

22. Why is soap not effective in hard
water?
• Because formation of scum
reduce the amount of soap
for cleaning and thus wastage
of soap occur.

23. Why is detergent more effective than
soap in hard water?
• Detergent form soluble salt with
calcium ion, Ca2+
or
magnesium ion, Mg2+
in hard
water.
• Therefore the cleaning power is
not affected by hard water.

24. Below are some additives in detergents.
Fill in missing words
Additives Functions
1 Drying agents
( such as sodium
sulphate, sodium
silicate)
to keep the
powder………
……….
DRY

25. Additives Functions
2 Builders
( such as
Sodium
triphosphate)
……………
water.
softe
n

26. Additives Functions
3 Biological
enzymes
( such as
amylase,
lipase)
to digest
in dirt or to
modify fabric
feel
PROTEIN, FAT
OR
CARBOHYDRA
TE

27. Additives Functions
4 Such as
sodium
perborate
Convert
stains into
…………………
substances
colourles
s

28. Additives Functions
5 Perfumes Make clothes
smell
……………. And
clean
fres
h

29. Additives Functions
6.
Stabilizers
( such as
silicones)
Prevent
formation of
………………foam

30. Change of one
homologous series to
another homologous
series
Question 3) Revision on alcohols, carboxylic
acids and ester

37. Alcohol
Carboxylic
acid
Ester
State the general formula for

38. Many reactions of ethanol

39. Reaction 1
• Combustion
• ethanol is burnt in excess oxygen
Observation: ethanol burns with blue
flame, no soot

40. Reaction 2
• Dehydration
• ethanol is passed over heated
porcelain chips to produce ethene
Observation: gas formed that will
decolorize brown bromine water

41. Reaction 3
• hydration or addition of steam
• When a mixture of ethene and steam is
heated over phosphoric acid as
catalyst, temp of 300o
C, pressure 60
atm.

42. Reaction 4
• Esterification
• When a mixture of ethanol and
ethanoic acid is warmed with conc
sulphuric acid as catalyst,
Observation: sweet smelling liquid is
formed

43. Reaction 5
• Esterification
• When a mixture of ethanoic acid and
ethanol is warmed with conc sulphuric
acid as catalyst
Observation: Sweet smelling liquid is formed

44. Reaction 6
• Oxidation
• When ethanol is warmed with acidified
potassium dichromate as oxidizing agent
Observation: Orange solution change to green

45. Naming of esters

46. 5) A student obtained the data to
determine heat of precipitation of PbSO4
Solution Vol
(cm3)
Conc
(moldm-
3)
Initial temp
(0
C)
Pb(NO3)2 50 0.5 27.4
Na2SO4 50 0.5 27.6
Highest temperature : 30.5 0
C
Question 4- thermochemistry

47. What is meant by heat of
precipitation?
• Heat changed when 1 mole of
precipitate is formed from its
ions in an aqueous solution

48. b) Calculate heat of precipitation of
PbSO4
• Mole Pb 2+
: (0.5)(50)/1000 = 0.025 mol
• Mole SO4
2-
: (0.5)(50)/1000 = 0.025
mol
• Pb2+
+ SO2-
4 PbSO4
mole PbSO4 = Mole Pb2+
or mole SO2-
4
= 0.025 mol

49. ϴ = 30.5 - ( 27.4 + 27.6 )
2
= 3.0 ° C
Heat of precipitation = mCϴ
mol
= ( 100)(4.2)(3)
0.025
= 50400 J/mol
∆ H = - 50.4 KJ/mol

50. d)Write thermo chemical equation
•Pb2+
+ SO4
2-
PbSO4
∆ H = - 50.4 KJ/mol

51. e) Write the ionic equation
•Pb2+
+ SO4
2-
PbSO4

52. E) Construct energy level diagram
Pb2+
+ SO4
2-
Energy
∆ H = - 50.4 KJ/mol
PbSO4

53. f) The experiment is repeated using K2SO4
to replaced Na2SO4. Heat of precipitation
of PbSO4 remain the same. Explain.
• Because the same precipitate is formed,
which is PbSO4.
• Only Pb 2+
ions and SO4
2-
ions react
• Na+
ions and K+
ions do not react

54. • 6) A student carried out an experiment
to determine heat of displacement of
copper from CuSO4 solution. He added
excess zinc powder to 50 cm3
of 0.2
moldm-3
CuSO4. The thermo chemical
equation is shown below :
Zn + Cu2+
Zn2+
+ Cu
∆ H = -80.64 KJ/mol

55. a) Calculate the change in
temperature
Mol Copper= mol copper(II) sulphate
= (0.2)(50)/1000 = 0.01 mol
∆ H = mCϴ
mol
80 640 J = ( 50)(4.2)(ϴ)
0.01
ϴ = 3.8 ° C

56. b) Write the ionic equation
Zn + CuSO4  Cu + ZnSO4
Zn + Cu2+ 
Zn2+
+ Cu

57. The experiment is repeated with the
following changes. What is the effect in
the change of temperature when :
• Concentration of CuSO4 is doubled,
without changing the volume :
So, change of temp or ϴ is doubled.
Because as the concentration
doubled, the number of particle per
unit volume also doubled.

58. The experiment is repeated with the
following changes. What is the effect
in the change of temperature when :
• volume of CuSO4 is halved, without
changing the concentration :
So, change of temp or ϴ is remain
the same. Because, the changes in
volume do not affect the number of
particles per unit volume

59. 7) State the diff betw heat change and the
heat of reaction
HEAT CHANGE HEAT OF REACTION
A)
OTHER
NAMES
Depends on name of
reactions :
Heat
absorb
, heat
released
-Heat of Precipitation
-Heat of displacement
-Heat of neutralisation
-Heat of combustion

60. 7) State the differences between heat
change and heat of reaction
HEAT CHANGE HEAT OF REACTION
B) FORMULA
USED
H= mCϴ ∆ H= mCϴ
mol
C)UNIT
Joule Kilo Joule/ mol
D) SYMBOL
none ∆ H
E) SIGN
No sign Either + for
endothermic rex or
– for exothermic rex