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TELEMATICS
GRADE 12
PHYSICAL SCIENCES NSC
ENGLISH
EXAMINATION QUESTION PAPERS
PHYSICS AND CHEMISTRY
November 2012
November 2011
March 2011
JANUARY 2013
Phy
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Exam question papers
2
NSC
PHYSICAL SCIENCES
Dear Grade 12 learner
Welcome to Physical Sciences. By now you know
that Physical Sciences is a challenging subject. You
also know that you have to understand and
remember what is taught each day. Therefore the
purpose of this guide is to show you what you have
to learn and do in your preparation for your Final
Examination.
CONTENT CHECKLIST
A summary of the content is provided below.
Physics
Vertical projectile motion
Relative velocity
Newton’s laws of motion, momentum, change in
momentum.
Impulse
Work, energy and power
Diffraction and interference
Doppler Effect
Electrostatics
Electric circuits
Electric motors and generators
Alternating current
Photo-electric effect
Electromagnetic radiation
Chemistry
Exothermic and endothermic reactions
Reaction Rate
Chemical equilibrium
Galvanic and electrolytic cells
Organic chemistry
Chemical processes and the Fertilizer Industry
Section A
It consists of:
One word items (5 marks)
Multiple choice questions (20 marks)
The total mark for section A is 25.
Section B
It consists of:
Longer questions.
The total mark for section B is 125.
TIPS FOR SUCCESS
1.
2.
3.
4.
5.
Teaching time is 4 hours per week. Ensure that
you exploit it optimally to learn!
Be ahead always. Research, read and calculate
to know the content and the experiment before
the lesson is taught on a daily basis.
The building blocks of science knowledge are
definitions, laws, principles and concepts. Know
and understand them first before you try to
remember and apply them.
The
subject
Physical
Sciences
uses
mathematical functions, concepts, operations and
calculus in its definitions, laws and principles.
Ensure that you know the relevant functions in
trigonometry, logarithms, indices, exponents, the
straight line, the hyperbola and the parabola.
Ensure that you know the basic operations of
addition, subtraction, multiplication, division and
factorisation in order to work with numbers and
variables. Know calculus and proportion also.
In Physical Sciences you are expected to do
science investigations and experiments. You
need to know and understand what independent,
dependent and control variables are before you
apply them. You also need to know and
understand what an investigative question and a
hypothesis are before you can formulate them
yourself.
ASSESSMENT REQUIREMENTS
For your year mark you will do the following tasks:
Two practical investigations
Two control tests
One research project
One June and one September Examination
These tasks make up 25% of the total mark for Physical
Sciences. The rest of the marks viz. 75% is allocated to
the Final Examination.
Final Examination
You will write two question papers, Paper 1 on Physics
and Paper 2 on Chemistry. The content that will be
assessed in each paper is listed in the content checklist
above. The total mark for each question paper is 150 and
the time allocated to complete it is 3 hours. Each question
paper consists of a section A and a section B.
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Exam question papers
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SECTION A
QUESTION 1: ONE-WORD ITEMS
Give ONE word/term for EACH of the following descriptions. Write only the word/term
next to the question number (1.1 – 1.5) in the ANSWER BOOK.
Nov 2012
1.1
The number of complete waves that pass a point in one second
(1)
1.2
A circuit component which stores electric charge and releases it instantly
(1)
1.3
The component in a generator needed to change it from an AC to a DC
generator
(1)
1.4
The tiny ‘packets’ (quanta) of energy that light consists of
(1)
1.5
The vector difference between two velocities measured in the same frame of
reference
(1)
[5]
Mar 2011
1.1
The product of the mass and velocity of a body
1.2
1.3
1.4
1.5
(1)
The term used to describe two sources that emit waves which maintain a
constant phase relation with each other
(1)
The type of spectrum formed when light is passed through a cold gas at low
pressure
(1)
The property of a conductor given by the ratio of the applied potential
difference to the current through the conductor
(1)
The 'packets of energy' (quanta) of which light consists
(1)
[5]
Nov 2011
1.1
The rate at which work is done
(1)
1.2
The term that describes two sources that produce waves that have a constant
phase relationship to each other
(1)
The general name given to the insulating material between the plates of
capacitors
(1)
1.4
The type of current produced by an electric generator which has slip rings
(1)
1.5
The unit of measurement of electric field
(1)
[5]
1.3
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QUESTION 2: MULTIPLE-CHOICE QUESTIONS
Nov 2012
Four options are provided as possible answers to the following questions. Each
question has only ONE correct answer. Choose the answer and write only the letter
(A – D) next to the question number (2.1 – 2.10) in the ANSWER BOOK.
The net force acting on an object is equal to the …
2.1
mass of the object.
B
acceleration of the object.
C
change in momentum of the object.
D
rate of change in momentum of the object.
0
time
Which ONE of the following graphs represents
acceleration-time graph for the motion of this object?
the
corresponding
0
time
acceleration
B
0
time
D
C
0
time
acceleration
acceleration
A
acceleration
(2)
The velocity-time graph below represents the motion of an object.
velocity
2.2
A
0
time
(2)
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2.3
A car moves up a hill at CONSTANT speed. Which ONE of the following
represents the work done by the weight of the car as it moves up the hill?
A
Ek
B
Ep
C
-Ek
D
-Ep
(2)
A central bright band is observed when light of wavelength  passes through
a single slit of width a.
2.4
Light of wavelength 2 is now used. Which ONE of the following slit widths
would produce a central bright band of the SAME broadness?
2.5
A
1
a
4
B
1
a
2
C
a
D
2a
(2)
A source of sound approaches a stationary listener in a straight line at
constant velocity. It passes the listener and moves away from him in the
same straight line at the same constant velocity.
Which ONE of the following graphs best represents the change in observed
frequency against time?
time (s)
time (s)
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time (s)
D
Frequency (Hz)
Frequency (Hz)
C
Frequency (Hz)
B
Frequency (Hz)
A
time (s)
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2.8
2.9
Which ONE of the following shows the different types of electromagnetic
radiation in order of increasing frequency?
A
X-rays; ultraviolet rays; infrared rays; visible light
B
Infrared rays; X-rays; visible light; ultraviolet rays
C
Infrared rays; visible light; ultraviolet rays; X-rays
D
X-rays; ultraviolet rays; visible light; infrared rays
(2)
A rectangular current-carrying coil, PQRS, is placed in a uniform magnetic
field with its plane parallel to the field as shown below. The arrows indicate
the direction of the conventional current.
axis
Q
R
N
O
R
T
H
S
O
U
T
H
P
S
The coil will …
A
rotate clockwise.
B
remain stationary.
C
rotate anticlockwise.
D
rotate clockwise and then anticlockwise
(2)
Mar 2011
2.1
Which ONE of the following physical quantities represents the RATE OF
CHANGE OF MOMENTUM of an object?
A
Force
B
Kinetic energy
C
Impulse
D
Acceleration
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2.10
The diagram below shows light incident on the cathode of a photocell. The
ammeter registers a reading.
Incident light
A
Which ONE of the following correctly describes the relationship between the
intensity of the incident light and the ammeter reading?
2.6
INTENSITY
AMMETER READING
A
Increases
Increases
B
Increases
Remains the same
C
Increases
Decreases
D
Decreases
Increases
(2)
The sketch below shows two small metal spheres, A and B, on insulated
stands carrying charges of magnitude q and 2q respectively. The distance
between the centres of the two spheres is r.
r
A
q
2q B
Sphere A exerts a force of magnitude F on sphere B. What is the magnitude
of the force that sphere B exerts on sphere A?
A
1
F
2
B
F
C
2F
D
4F
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2.9
The cross () in the diagram below represents a conductor carrying
conventional current INTO THE PAGE in the uniform field between the two
bar magnets. The conductor is placed between the north (N) pole and south
(S) pole of the magnets, as shown.
A
N
S
B
⊗
D
S
N
C
In which ONE of the directions A, B, C or D (all lying in the plane of the page)
will this conductor experience a force?
A
A
B
B
C
C
D
D
(2)
Nov 2011
A ball is released from rest from a certain height above the floor and bounces
off the floor a number of times. The position-time graph below represents the
motion of the bouncing ball from the instant it is released from rest.
position (m)
2.3
A
●
C
●
●
B
●
D
time (s)
Neglecting air resistance, which point (A, B, C or D) on the graph represents
the position-time coordinates of the maximum height reached by the ball after
the SECOND bounce?
A
A
B
B
C
C
D
D
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2.6
A set of identical light bulbs are connected as shown in the circuit diagrams
below. The internal resistance of the battery is negligible.
In which ONE of these circuits will the light bulbs glow the brightest?
A
B
C
D
(2)
2.8
Point P is a distance x from the positive plate of a parallel-plate capacitor as
shown in the diagram below.
+
+
+
+
+
x
•P
-
The magnitude of the electric field at P is E. At a distance
1
x from the
2
positive plate, the magnitude of the electric field will be …
A
1
E
4
B
1
E
2
C
E
D
2E
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SECTION B
QUESTION 3
Nov 2012
An object is projected vertically upwards at 8 m.s-1 from the roof of a building which is
60 m high. It strikes the balcony below after 4 s. The object then bounces off the
balcony and strikes the ground as illustrated below. Ignore the effects of friction.
building
8 m.s-1
60 m
balcony
h
3.1
3.2
Is the object’s acceleration at its maximum height UPWARD, DOWNWARD or
ZERO?
(1)
Calculate the:
3.2.1
Magnitude of the velocity at which the object strikes the balcony
(4)
3.2.2
Height, h, of the balcony above the ground.
(5)
The object bounces off the balcony at a velocity of 27,13 m.s -1 and strikes the ground
6 s after leaving the balcony.
3.3
Sketch a velocity-time graph to represent the motion of the object from the
moment it is projected from the ROOF of the building until it strikes the
GROUND. Indicate the following velocity and time values on the graph:





The initial velocity at which the object was projected from the roof of
the building
The velocity at which the object strikes the balcony
The time when the object strikes the balcony
The velocity at which the object bounces off the balcony
The time when the object strikes the ground
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QUESTION 3
Mar 2011
The velocity-time graph shown below represents the motion of two objects, A and B,
released from the same height. Object A is released from REST and at the same
instant object B is PROJECTED vertically upwards. (Ignore the effects of friction.)
20
velocity (m·s-1)
10
B
0
1
5
2
6
3
4
time (s)
7
- 10
A
- 20
- 30
- 40
Object A undergoes a constant acceleration. Give a reason for this statement
by referring to the graph. (No calculations are required.)
(2)
3.2
At what time/times is the SPEED of object B equal to 10 m∙s-1?
(2)
3.3
What is the velocity of object A relative to object B at t = 1 s?
(3)
3.4
Object A strikes the ground after 4 s. USE EQUATIONS OF MOTION to
calculate the height from which the objects were released.
(3)
What physical quantity is represented by the area between the graph and the
time axis for each of the graphs A and B?
(2)
3.1
3.5
3.6
Calculate, WITHOUT USING EQUATIONS OF MOTION, the distance
between objects A and B at t = 1 s.
QUESTION 3
Nov 2011
A hot-air balloon is moving vertically upwards at a constant speed. A camera is
accidentally dropped from the balloon at a height of 92,4 m as shown in the diagram
below. The camera strikes the ground after 6 s. Ignore the effects of friction.
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vi
92,4 m
10 m
P
3.1
3.2
3.3
At the instant the camera is dropped, it moves upwards. Give a reason for this
observation.
(1)
Calculate the speed vi at which the balloon is rising when the camera is
dropped.
(4)
Draw a sketch graph of velocity versus time for the entire motion of the
camera.
Indicate the following on the graph:


3.4
Initial velocity
Time at which it reaches the ground
(4)
If a jogger, 10 m away from point P as shown in the above diagram and
running at a constant speed of 2 m∙s-1, sees the camera at the same instant it
starts falling from the balloon, will he be able to catch the camera before it
strikes the ground?
Use a calculation to show how you arrived at the answer.
QUESTION 4
(5)
[14]
November 2012
A car of mass m is travelling at 20 m.s-1 east on a straight level road. A truck of mass
2m is travelling west at 20 m.s-1 on the same road.
20 m∙s-1
20 m∙s-1
E
4.1
Calculate the velocity of the car relative to the truck.
(2)
The vehicles collide head-on and stick together during the collision.
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4.2
State the principle of conservation of linear momentum in words.
(2)
4.3
Calculate the velocity of the truck-car system immediately after the collision.
(6)
4.4
On impact the car exerts a force of magnitude F on the truck and experiences
an acceleration of magnitude a.
4.4.1
Determine, in terms of F, the magnitude of the force that the truck exerts on
the car on impact. Give a reason for your answer.
(2)
4.4.2
Determine, in terms of a, the acceleration that the truck experiences on
impact. Give a reason for the answer.
(2)
4.4.3
Both drivers are wearing identical seat belts. Which driver is more likely to be
severely injured on impact? Explain the answer by referring to
ACCELERATION and VELOCITY.
QUESTION 4
(3)
[17]
November 2011
A patrol car is moving on a straight horizontal road at a velocity of 10 m∙s-1 east. At the
same time a thief in a car ahead of him is driving at a velocity of 40 m∙s-1 in the same
direction.
vPG = 10 m∙s-1
vTG = 40 m∙s-1
VPG = 10
m∙s-1
vPG: velocity of the patrol car relative to the ground
vTG: velocity of the thief’s car relative to the ground
4.1
Write down the velocity of the thief's car relative to the patrol car.
(2)
A person in the patrol car fires a bullet at the thief's car. The bullet leaves the gun with
an initial horizontal velocity of 100 m∙s-1 relative to the patrol car. Ignore the effects of
friction.
4.2
Write down the initial velocity of the bullet relative to the thief's car.
(2)
While travelling at 40 m∙s-1, the thief's car of mass 1 000 kg, collides head-on with a
truck of mass 5 000 kg moving at 20 m∙s-1. After the collision, the car and the truck
move together. Ignore the effects of friction.
20 m∙s-1
40 m∙s-1
4.3
State the law of conservation of linear momentum in words.
(2)
4.4
Calculate the velocity of the thief's car immediately after the collision.
(6)
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4.5
Research has shown that forces greater than 85 000 N during collisions may
cause fatal injuries. The collision described above lasts for 0,5 s.
Determine, by means of a calculation, whether the collision above could result
in a fatal injury.
QUESTION 4
(5)
[17]
Mar 2011
Two shopping trolleys, X and Y, are both moving to the right along the same straight
line. The mass of trolley Y is 12 kg and its kinetic energy is 37,5 J.
4.1
Calculate the speed of trolley Y.
(3)
Trolley X of mass 30 kg collides with trolley Y and they stick together on impact. After
the collision, the combined speed of the trolleys is 3,2 m∙s-1. (Ignore the effects of
friction.)
X
Y
After the collision
Before the collision
4.2
Write down the principle of conservation of linear momentum in words.
(2)
4.3
Calculate the speed of trolley X before the collision.
(5)
During the collision, trolley X exerts a force on trolley Y. The collision time is 0,2 s.
4.4
Calculate the magnitude of the force that trolley X exerts on trolley Y.
QUESTION 5
November 2012
In order to measure the net force involved in a collision, a car is allowed to collide
head-on with a flat, rigid barrier. The resulting crumpling distance is measured. The
crumple distance is the length by which the car becomes shorter in coming to rest.
Before collision
x1
After collision
x2
In one of the tests, a car of mass 1200 kg strikes the barrier at a speed of 20 m.s -1.
The crumple distance, (x1 – x2), is measured as 1,02 m. (Ignore the effects of frictional
forces during crumpling.)
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5.1
Draw a labelled free-body diagram showing ALL the forces acting on the car
during the collision.
(3)
5.2
State the work-energy theorem in words.
(2)
5.3
Assume that the net force is constant during crumpling.
5.3.1
5.3.2
USE THE WORK-ENERGY THEOREM to calculate the magnitude of
the net force exerted on the car as it is brought to rest during
crumpling.
(4)
Calculate the time it takes the car to come to rest during crumpling.
(4)
QUESTION 5
Mar 2011
A crate of mass 70 kg slides down a rough incline that makes an angle of 20° with the
horizontal, as shown in the diagram below. The crate experiences a constant frictional
force of magnitude 190 N during its motion down the incline. The forces acting on the
crate are represented by R, S and T.
T
R
12 m

A
S

B
20°
5.1
Label the forces R, S and T.
(3)
5.2
Give a reason why force R does no work on the crate.
(2)
The crate passes point A at a speed of 2 m∙s-1 and moves a distance of 12 m before
reaching point B lower down on the incline.
5.3
Calculate the net work done on the crate during its motion from point A to
point B.
(5)
5.4
Write down the work-energy theorem in words.
(2)
5.5
Use the work-energy theorem to calculate the speed of the crate at point B.
(4)
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QUESTION 5
Nov 2011
A rescue helicopter is stationary (hovers) above a soldier. The soldier of mass 80 kg is
lifted vertically upwards through a height of 20 m by a cable at a CONSTANT SPEED
of 4 m∙s-1. The tension in the cable is 960 N. Assume that there is no sideways motion
during the lift. Air friction is not to be ignored.
960 N
80 kg
5.1
State the work-energy theorem in words.
(2)
5.2
Draw a labelled free-body diagram showing ALL the forces acting on the
soldier while being lifted upwards.
(3)
Write down the name of a non-contact force that acts on the soldier during the
upward lift.
(1)
5.3
5.4
Use the WORK-ENERGY THEOREM to calculate the work done on the
soldier by friction after moving through the height of 20 m.
QUESTION 6
(5)
[11]
Nov 2012
A bird flies directly towards a stationary birdwatcher at constant velocity. The bird
constantly emits sound waves at a frequency of 1600 Hz. The birdwatcher hears a
change in pitch as the bird comes closer to him.
6.1
Write down the property of sound that is related to pitch.
(1)
6.2
Give a reason why the birdwatcher observes a change in pitch as the bird
approaches him.
(1)
Air pressure
The air pressure versus distance graph below represents the waves detected by the
birdwatcher as the bird comes closer to him. The speed of sound in air is 340 m.s -1.
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0
0,1
0,2 0,3 0,4 0,5
Distance (m)
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6.3
From the graph, write down the wavelength of the detected waves.
6.4
Calculate the:
(1)
6.4.1
Frequency of the waves detected by the birdwatcher.
(3)
6.4.2
Magnitude of the velocity at which the bird flies.
(5)
[11]
QUESTION 6
Mar 2011
The whistle of a train emits sound waves of frequency 2 000 Hz. A stationary listener
measures the frequency of these emitted sound waves as 2 080 Hz. The speed of
sound in air is 340 m·s-1.
6.1
Name the phenomenon responsible for the observed change in frequency.
(1)
6.2
Is the train moving AWAY FROM or TOWARDS the stationary listener?
(1)
6.3
Calculate the speed of the train.
(4)
6.4
Will the frequency observed by a passenger, sitting in the train, be GREATER
THAN, EQUAL TO or SMALLER THAN 2 000 Hz? Explain the answer.
QUESTION 6
(2)
[8]
Nov 2011
A train approaches a station at a constant speed of 20 m∙s-1 with its whistle blowing at
a frequency of 458 Hz. An observer, standing on the platform, hears a change in pitch
as the train approaches him, passes him and moves away from him.
6.1
6.2
6.3
6.4
Name the phenomenon that explains the change in pitch heard by the
observer.
(1)
Calculate the frequency of the sound that the observer hears while the train is
approaching him. Use the speed of sound in air as 340 m∙s-1.
(4)
How will the observed frequency change as the train passes and moves away
from the observer? Write down only INCREASES, DECREASES or
REMAINS THE SAME.
(1)
How will the frequency observed by the train driver compare to that of the
sound waves emitted by the whistle? Write down only GREATER THAN,
EQUAL TO or LESS THAN. Give a reason for the answer.
QUESTION 7
Nov 2011
A learner investigates the change in broadness of the central bright band in a
diffraction pattern when light passes through single slits of different widths. She uses
monochromatic violet light of wavelength 4 x 10-7 m. The apparatus is set up as shown
in the diagram below.
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single slit
monochromatic
violet light
screen
a
θ
7.1
Define the term monochromatic light.
(2)
7.2
Write down the investigative question for this investigation.
(2)
7.3
Write down TWO variables that are kept constant during this investigation.
(2)
7.4
The learner now uses a narrower slit.
How will the broadness of the central bright band change? Write down only
INCREASES, DECREASES or REMAINS THE SAME.
Give an explanation.
7.5
(2)
Calculate the angle θ at which the second minimum is formed if a slit of width
2,2 x 10-6 m is used.
QUESTION 7
(5)
[13]
Nov 2012
Learners use monochromatic blue light to investigate the difference between an
interference pattern and a diffraction pattern.
Apart from the blue light and the screen, write down the name of ONE item
that the learners will need to obtain an interference pattern.
(1)
7.2
Briefly describe the interference pattern that will be observed on the screen.
(2)
7.3
In one of their experiments they place the screen at a distance of 1,4 m from
a single slit and observe a pattern on the screen. The width of the central
bright band is measured as 22 cm.
Screen
Monochromatic
blue light
θ
22 cm
7.1
1,4 m
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Calculate the:
7.3.1
Angle θ which the first minimum will be observed on the screen.
(3)
7.3.2
The width of the slit used if the wavelength of the blue light is 470 nm
(5)
7.4
The width of the central band INCREASES when the blue light is replaced
with monochromatic re light. Explain this observation.
QUESTION 7
(2)
[13]
Mar 2011
Learners perform an experiment with monochromatic light. They pass the light through
a single slit. The distance between the screen and the slit is kept constant.
The diagram below represents the pattern observed during the experiment.
KEY
Dark band
Bright band
x
The slit has a width of 0,02 mm and the SECOND dark band is formed on the screen
at an angle of 3° from the centre of the slit.
7.1
Define the term diffraction.
(2)
7.2
Calculate the wavelength of this light.
(4)
7.3
The light used is either green or red. Given that yellow light has a wavelength
of 577 nm, which colour is used? Give a reason for your answer.
(2)
Using the same light as in QUESTION 7.2, write down TWO experimental
changes that can be made to decrease the distance x in the diagram above.
(2)
7.4
7.5
Describe the pattern that will be observed if the single slit is now replaced with
a double slit.
QUESTION 9
Mar 2011
The circuit diagram below represents a combination of resistors in series and parallel.
The battery has an emf of 12 V and an unknown internal resistance r.
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 = 12 V
r
A
P•
•
S
•
8 
6 
•Q
3,6 
With switch S OPEN, ammeter A gives a reading of 1,2 A.
9.1
Calculate the total resistance of the circuit.
(3)
9.2
Calculate the internal resistance of the battery.
(4)
9.3
Calculate the energy dissipated in the 6  resistor in 3 minutes.
(3)
Switch S is now CLOSED.
9.4
9.5
How will EACH of the following be affected? Write down only INCREASES,
DECREASES or REMAINS THE SAME.
9.4.1
The total resistance of the circuit
(1)
9.4.2
The reading on ammeter A
(1)
A conducting wire of negligible resistance is now connected between points P
and Q. What effect will this have on the temperature of the battery?
Write down only INCREASES, DECREASES or REMAINS THE SAME.
Explain how you arrived at the answer.
QUESTION 11
11.1
Mar 2011
A group of learners performs an investigation to compare the effect of two
types of radiation on the emission of photoelectrons from zinc. They place a
zinc plate on top of the disc of a negatively charged electroscope. Ultraviolet
and red light are shone alternately onto the zinc plate as shown below, with
the electroscope fully charged in each case.
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radiation
zinc plate
disc
- -
gold leaves
electroscope
They record the following observations:
RADIATION
Ultraviolet light
Red light
OBSERVATION
Gold leaves collapse
No effect on the deflection of gold leaves
11.1.1
Write down an INVESTIGATIVE QUESTION for this investigation.
(2)
11.1.2
Explain the observation made for ultraviolet light.
(3)
11.1.3
What conclusion can be drawn from this investigation?
(2)
11.1.4
The following safety precaution is printed on the ultraviolet light
source:
OVEREXPOSURE TO ULTRAVIOLET LIGHT IS A HEALTH RISK
Name ONE health risk associated with overexposure to ultraviolet
light.
11.2
(1)
The learners have access to the following information:
Work function of zinc
Frequency of ultraviolet light
Frequency of red light
6,88 x 10-19 J
7,89 x 1014 Hz
4,29 x 1014 Hz
11.2.1
Define the term work function of a metal.
(2)
11.2.2
Name ONE type of electromagnetic radiation with a higher
frequency than that of ultraviolet light.
(1)
11.2.3
QUESTION 12
Use a calculation to explain why red light fails to emit
photoelectrons from the surface of the zinc plate.
Nov 2011
A metal surface is illuminated with ultraviolet light of wavelength 330 nm. Electrons are
emitted from the metal surface.
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The minimum amount of energy required to emit an electron from the surface of this
metal is 3,5 x 10-19 J.
ultraviolet light
electrons
metal
12.1
Name the phenomenon illustrated above.
(1)
12.2
Give ONE word or term for the underlined sentence in the above paragraph.
(1)
12.3
Calculate the frequency of the ultraviolet light.
(4)
12.4
Calculate the kinetic energy of a photoelectron emitted from the surface of the
metal when the ultraviolet light shines on it.
(4)
12.5
The intensity of the ultraviolet light illuminating the metal is now increased.
What effect will this change have on the following:
12.5.1
12.5.2
12.6
Kinetic energy of the emitted photoelectrons (Write down only
INCREASES, DECREASES or REMAINS THE SAME.)
(1)
Number of photoelectrons emitted per second (Write down only
INCREASES, DECREASES or REMAINS THE SAME.)
(1)
Overexposure to sunlight causes damage to skin cells.
12.6.1
12.6.2
QUESTION 11
Which type of radiation in sunlight is said to be primarily
responsible for this damage?
Name the property of this radiation responsible for the damage.
Nov 2011
During an investigation, light of different frequencies is shone onto the metal cathode
of a photocell. The kinetic energy of the emitted photoelectrons is measured. The
graph below shows the results obtained.
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Kinetic energy (J)
NSC
E1
0
5 x 1014
11.1
10 x 1014
15 x 1014
Frequency (Hz)
For this investigation, write down the following:
11.1.1
Dependent variable
(1)
11.1.2
Independent variable
(1)
11.1.3
Control variable
(1)
11.2
Define the term threshold frequency.
(2)
11.3
Use the graph to obtain the threshold frequency of the metal used as cathode
in the photocell.
(1)
11.4
Calculate the kinetic energy at E1 shown in the graph.
(4)
11.5
How would the kinetic energy calculated in QUESTION 11.4 be affected if
light of higher intensity is used? Write down only INCREASES, DECREASES
or REMAINS THE SAME
(1)
[11]
QUESTION 8
Nov 2011
The diagram below shows a small metal sphere P on an insulated stand. The sphere
carries a charge of -4 x 10-9 C, as shown in the diagram.
-4 x 10-9 C
8.1
-
P
Draw the electric field pattern around sphere P.
charges affect this pattern.
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8.2
Calculate the number of electrons in excess on sphere P.
(2)
A second metal sphere T carrying a charge of +2 x 10-9 C is placed 1 cm from
sphere P, as shown in the diagram below.
1 cm
-4 x 10-9 C
8.3
-
P
+2 x 10-9 C
+
T
Calculate the magnitude of the electrostatic force that sphere P exerts on
sphere T.
(4)
The spheres are now brought into contact with each other and returned to their original
positions.
8.4
Calculate the electric potential energy of the system of two charges.
QUESTION 9
Mar 2011
The circuit diagram below represents a combination of resistors in series and parallel.
The battery has an emf of 12 V and an unknown internal resistance r.
 = 12 V
r
A
P•
•
S
•
8 
6 
•Q
3,6 
With switch S OPEN, ammeter A gives a reading of 1,2 A.
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9.1
Calculate the total resistance of the circuit.
(3)
9.2
Calculate the internal resistance of the battery.
(4)
9.3
Calculate the energy dissipated in the 6  resistor in 3 minutes.
(3)
Switch S is now CLOSED.
9.4
9.5
How will EACH of the following be affected? Write down only INCREASES,
DECREASES or REMAINS THE SAME.
9.4.1
The total resistance of the circuit
(1)
9.4.2
The reading on ammeter A
(1)
A conducting wire of negligible resistance is now connected between points P
and Q. What effect will this have on the temperature of the battery?
Write down only INCREASES, DECREASES or REMAINS THE SAME.
Explain how you arrived at the answer.
QUESTION 8
(4)
[16]
Nov 2011
Two metal spheres, P and T, on insulated stands, carry charges of +3 x 10-9 C and
-6 x 10-9 C respectively.
+3 x 10-9 C
P
T
-6 x 10-9 C
The spheres are allowed to touch each other and are then placed 1,5 m apart as
shown below.
1,5 m
P
8.1
8.2
8.3
T
In which direction will electrons flow while spheres P and T are in contact?
Write down only FROM P TO T or FROM T TO P.
(1)
Calculate the net charge gained or lost by sphere P after the spheres have
been in contact.
(3)
Calculate the number of electrons transferred during the process in
QUESTION 8.2.
(2)
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8.4
A third sphere R, carrying a charge of -3 x 10-9 C, is NOW placed between P
and T at a distance of 1 m from T.
Calculate the net force experienced by sphere R as a result of its interaction
with P and T.
QUESTION 5
(6)
[12]
Nov 2012
The flow diagram below shows how three organic compounds can be prepared from
2-bromo-3-methylbutane.
Compound A
Compound B
Reaction 2
Reaction 1
Reaction 3
2-bromo-3-methylbutane
An alkene
5.1
5.2
Write down the:
5.1.1
Homologous series to which 2-bromo-3-methylbutane belongs
(1)
5.1.2
Structural formula of 2-bromo-3-methylbutane
(2)
Reaction 2 takes place in the presence of a dilute sodium hydroxide solution.
Write down the:
5.3
5.2.1
Name of the type of reaction which takes place
(1)
5.2.2
Structural formula of compound B
(2)
Reaction 1 takes place in the presence of concentrated sodium hydroxide.
Write down:
5.4
5.31
Another reaction condition needed for this reaction
(1)
5.3.2
The name of the type of reaction that takes place
(1)
5.3.3
The structural formula of compound A, the major product formed
(2)
Reaction 3 takes place when compound B is heated in the presence of
concentrated sulphuric acid. Write down the IUPAC name of the major
product formed.
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QUESTION 5
Nov 2011
In the flow diagram below R, P and Q represent different types of reactions.
CH3
CH
CH2
P
Alcohol X
(major product)
R
CH3CHBrCH3
5.1
Q
Alcohol Y
Name the type of reaction represented by:
5.1.1
P
(1)
5.1.2
Q
(1)
5.1.3
R
(1)
5.2
Using structural formulae, write down a balanced equation for reaction P.
(4)
5.3
Write down the IUPAC name of alcohol Y.
(2)
5.4
Reaction Q takes place in the presence of a BASE. Write down TWO reaction
conditions for this reaction.
QUESTION 5
5.1
(2)
[11]
Mar 2011
Prop-1-ene, an UNSATURATED hydrocarbon, and compound X, a
SATURATED hydrocarbon, react with chlorine, as represented by the
incomplete equations below.
Reaction I:
Prop-1-ene + Cℓ2 →
Reaction II:
X + Cℓ2 →
2-chlorobutane + Y
5.1.1
Give a reason why prop-1-ene is classified as unsaturated.
5.1.2
What type of reaction (ADDITION or SUBSTITUTION) takes place
in the following:
5.1.3
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(1)
(a)
Reaction I
(1)
(b)
Reaction II
(1)
Write down the structural formula of the product formed in
Reaction I.
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5.1.4
5.2
Write down the reaction condition necessary for Reaction II to take
place.
(1)
5.1.5
Write down the IUPAC name of reactant X.
(1)
5.1.6
Write down the name or formula of product Y.
(1)
2-chlorobutane can either undergo ELIMINATION or SUBSTITUTION in the
presence of a strong base such as sodium hydroxide.
5.2.1
5.2.2
5.2.3
5.2.4
5.3
Which reaction will preferably take place when 2-chlorobutane is
heated in the presence of CONCENTRATED sodium hydroxide in
ethanol? Write down only SUBSTITUTION or ELIMINATION.
(1)
Write down the IUPAC name of the major organic compound formed
in QUESTION 5.2.1.
(2)
Use structural formulae to write down a balanced equation for the
reaction that takes place when 2-chlorobutane reacts with a DILUTE
sodium hydroxide solution.
(6)
Write down the name of the type of substitution reaction that takes
place in QUESTION 5.2.3.
(1)
Haloalkanes are used in insecticides (insect killers).
5.3.1
Write down ONE POSITIVE impact of insecticides on human
development.
5.3.2
Write down ONE NEGATIVE impact of insecticides on humans.
QUESTION 6
(2)
(2)
[22]
Nov 2012
Calcium carbonate chips are added to an excess dilute hydrochloric acid solution in a
flask placed on a balance as illustrated below. The cotton wool plug in the mouth of the
flask prevents spillage of reactants and products, but simultaneously allows the formed
gas to escape. The balanced chemical equation for the reaction that takes place is:
CaCO3(s) + 2HCℓ(aq)  CaCℓ2(aq) + CO2(g) + H2O(ℓ)
6.1
Write down the NAME of the gas that escapes through the cotton wool plug
while the reaction takes place.
The loss in mass of the flask and its contents is recorded in intervals of 2 minutes. The
results obtained are shown in the graph below.
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Loss in mass (g)
NSC
6.2
6.4
6.5
6.6
• •
2,5
2,0
• • •
• •
•
1,5
1,0
0,5
0
•0
5
10
Time (minutes)
15
20
From the graph write down the following:
6.2.1
6.3
Graph of loss in mass versus time
4,5
4,0
3,5
3,0
The coordinates of the point that represents results that were
measured incorrectly
(1)
6.2.2
How long (in minutes) the reaction lasts
(1)
6.2.3
How long (in minutes) it takes 75% (three quarters) of the reaction to
occur
(1)
The experiment is now repeated using hydrochloric acid of a higher
concentration. It is found that the rate of the reaction INCREASES. Use the
collision theory to explain this observation.
(2)
How would a higher concentration of hydrochloric acid affect the following:
(Write down only INCREASES, DECREASES or REMAINS THE SAME.)
6.4.1
Loss in mass per unit time
(1)
6.4.2
Total loss in mass
(1)
6.4.3
Time for the reaction to reach completion
(1)
Apart from concentration and temperature changes, write down TWO other
changes that can be made to increase the rate of this reaction.
(2)
Calculate the mass of calcium carbonate used when the reaction is
completed. Assume that all the gas that was formed, escaped from the flask.
(5)
[ 16]
QUESTION 6
Nov 2011
Learners use copper(II) oxide POWDER to decompose hydrogen peroxide. They add
1 g copper(II) oxide to 100 cm3 hydrogen peroxide in a flask connected to a delivery
tube. The reaction that takes place is represented by the following balanced equation:
CuO(s)
2H2O2(ℓ)
2H2O(ℓ) + O2(g)
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6.1
Write down the name of ONE item of apparatus that can be used to measure
the volume of the gas produced.
(1)
The volume of oxygen gas produced is measured every 10 seconds. The results
obtained are shown in the graph below.
70
Volume of oxygen gas (cm3)
60
50
40
30
20
10
0
0
90
80
40
60
70
50
Time (s)
Use the graph to determine the volume of oxygen gas collected in the
container at 15 seconds.
(2)
How does the rate of the reaction change between t = 40 s and t = 70 s?
Write down only INCREASES, DECREASES or REMAINS THE SAME. Refer
to the graph to explain the answer.
(2)
6.4
What is the function of the copper(II) oxide in this reaction?
(1)
6.5
Apart from oxygen, write down the NAMES or FORMULAE of TWO
substances present in the flask after 90 seconds.
(2)
The learners found that oxygen is produced at a slower rate when 1 g of a
SOLID LUMP of copper(II) oxide is used. Fully explain this observation.
(2)
6.2
6.3
6.6
6.7
10
20
30
It is known that bad breath is due to bacterial activity in the mouth in the
absence of oxygen.
Use the reaction above to explain why a solution containing hydrogen
peroxide can be used as mouthwash to improve bad breath.
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QUESTION 6
Mar 2011
Learners perform three investigations (A, B and C) to study three factors which affect
the rate of chemical reactions. They use the reaction between solid calcium carbonate
(CaCO3) and excess hydrochloric acid (HCℓ) solution, represented by the balanced
equation below, in all three investigations.
CaCO3(s) + 2HCℓ(aq) → CaCℓ2(aq) + H2O(ℓ) + CO2(g)
EXCESS HYDROCHLORIC ACID is used and
COMPLETELY COVERED in all the investigations.
6.1
the
calcium
carbonate
is
INVESTIGATION A:
The learners conduct two experiments using the conditions as shown in the
table below.
Experiment 1
Experiment 2
Mass of
CaCO3 (g)
2
2
State of CaCO3
powder
lumps
Concentration of
HCℓ (mol∙dm-3)
0,2
0,2
Temperature of
HCℓ (°C)
25
25
6.1.1
Which factor influencing reaction rate is investigated?
(1)
6.1.2
Write down an INVESTIGATIVE QUESTION for this investigation.
(2)
6.1.3
The learners now repeat Experiment 1, but use 4 g of calcium
carbonate in excess acid, instead of 2 g. They find that the rate of
the reaction INCREASES.
Give a reason why the rate increases.
6.2
(2)
INVESTIGATION B:
The learners conduct two experiments using the conditions as shown in the
table below.
Experiment 3
Experiment 4
Mass of
CaCO3 (g)
2
2
State of
CaCO3
lumps
lumps
Concentration of
HCℓ (mol∙dm-3)
0,2
1,0
Temperature of
HCℓ (°C)
25
25
6.2.1
Identify the independent variable in this investigation.
(1)
6.2.2
Write down a hypothesis for this investigation.
(2)
6.2.3
Is it fair to compare results obtained in Experiment 3 with that in
Experiment 4? Give a reason for the answer.
(2)
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6.2.4
6.3
The reactions in Experiments 3 and 4 both run to completion. How
will the yield of CO2(g) in Experiment 3 compare to that in
Experiment 4? Write down only LARGER THAN, SMALLER
THAN or EQUAL TO and give a reason for the answer.
(2)
INVESTIGATION C:
The learners conduct two experiments using the conditions as shown in the
table below.
Experiment 5
Experiment 6
6.3.1
6.3.2
State of
CaCO3
powder
powder
Concentration of
HCℓ (mol∙dm-3)
0,2
0,2
Temperature of
HCℓ (°C)
25
35
How does the average kinetic energy of the particles in the reaction
in Experiment 5 compare to that in Experiment 6? Write down
only HIGHER THAN, LOWER THAN or EQUAL TO.
(1)
On the same set of axes, draw sketch graphs of the number of
molecules versus the kinetic energy (Maxwell-Boltzmann
distribution curves) for each of Experiment 5 and Experiment 6.

Label the axes.

Clearly label each graph as Experiment 5 or Experiment 6.
(3)
The graph below shows changes in the potential energy for the reaction
between calcium carbonate and hydrochloric acid.
Potential energy (kJ)
6.4
Mass of
CaCO3 (g)
4
4
A
B
C
Course of reaction
6.4.1
6.4.2
Is this reaction endothermic or exothermic? Give a reason for the
answer.
Use the relevant energy values, A, B and C, to write down an
expression for each of the following:
(a)
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(2)
The energy of the activated complex
(1)
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(b)
QUESTION 7
∆H for the forward reaction
(1)
[20]
Nov 2012
A hypothetical reaction is represented by the balanced equation below.
A(g) + 2B(g)
2C(g)
Initially 3 moles of A(g) and 6 moles of B(g) are mixed in a 5 dm 3 sealed container.
When the reaction reaches equilibrium at 25 oC, it is found that 4 moles of B(g) is
present
7.1
Define the term chemical equilibrium
(2)
7.2
Show by calculation that the equilibrium concentration of C(g) is 0,4 mol.dm -3.
(3)
7.3
How will an increase in pressure, by decreasing the volume of the container,
influence the amount of C(g) in the container at 25 oC?
Write down INCREASES, DECREASES or REMAINS THE SAME. Explain
the answer
(3)
7.4
The initial number of moles of B(g) is now increased while the initial number
of moles of A(g) remains constant at 25 oC.
Calculate the number of moles of B(g) that must be ADDED to the original
amount (6 mol) so that the concentration of C(g) is 0,8 mol.dm -3 at
equilibrium. The equilibrium constant (Kc) for this reaction at 25 oC is 0,625.
QUESTION 7
7.1
(9)
[17]
Nov 2011
The industrial preparation of hydrogen gas is represented by the equation
below.
CH4(g) + H2O(g) ⇌ CO(g) + 3H2(g)
∆H > 0
The reaction reaches equilibrium at 1 000 °C in a closed container.
7.1.1
State Le Chatelier's principle.
(3)
7.1.2
How will an increase in pressure at 1 000 °C (by decreasing the
volume) affect the yield of hydrogen gas? Write down only
INCREASES, DECREASES OR NO EFFECT. Explain the answer.
(3)
Give TWO reasons why high temperatures are used for this
reaction.
(2)
7.1.3
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7.2
Study the reversible reaction represented by the balanced equation below.
H2(g) + CO2(g) ⇌ H2O(g) + CO(g)
Initially x moles of H2(g) is mixed with 0,3 moles of CO2(g) in a sealed
10 dm3 container. When equilibrium is reached at a certain temperature, it is
found that 0,2 moles of H2O(g) is present.
The equilibrium constant (Kc) for the reaction at this temperature is 4.
7.2.1
7.2.2
Calculate the initial number of moles of H2(g), x, that was in the
container.
The reaction is now carried out at a much higher temperature. It is
found that Kc decreases at this higher temperature.
Is this reaction exothermic or endothermic? Explain the answer.
QUESTION 7
(8)
(3)
[19]
Mar 2011
Fertilisers allow farmers to grow crops in the same soil year after year. However,
environmental problems, such as eutrophication, are associated with the application of
fertilisers.
7.1
State ONE PRECAUTION that a maize farmer can take to prevent
eutrophication.
(1)
Nitric acid is an important reactant in the production of ammonium nitrate, a nitrogenbased fertiliser.
7.2
Write down the name of the industrial process for the production of nitric acid.
(1)
7.3
Write down a balanced equation for the preparation of ammonium nitrate from
nitric acid.
(3)
A fertiliser company produces ammonia on a large scale at a temperature of 450 °C.
The balanced equation below represents the reaction that takes place in a sealed
container.
N2(g) + 3H2(g) ⇌ 2NH3(g)
∆H < 0
To meet an increased demand for fertiliser, the management of the company instructs
their engineer to make the necessary adjustments to increase the yield of ammonia.
In a trial run on a small scale in the laboratory, the engineer makes adjustments to the
TEMPERATURE, PRESSURE and CONCENTRATION of the equilibrium mixture.
The graphs below represent the results obtained.
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Concentration (mol∙dm-3)
NSC
N2
H2
NH3
0
t1
t2
t3
Time (minutes)
7.4
7.5
7.6
Identify the changes made to the equilibrium mixture at each of the following
times:
7.4.1
t1
(2)
7.4.2
t2
(2)
7.4.3
t3
(2)
At which of the above time(s) did the change made to the reaction mixture
lead to a higher yield of ammonia? Write down only t1 and/or t2 and/or t3.
The engineer now injects 5 mol N2 and 5 mol H2 into a 5 dm3 sealed empty
container. Equilibrium is reached at 450 °C. Upon analysis of the equilibrium
mixture, he finds that the mass of NH3 is 20,4 g.
Calculate the value of the equilibrium constant (Kc) at 450 °C .
QUESTION 8
8.1
(9)
[22]
Nov 2012
A strip of aluminium is placed in a beaker containing a blue solution of a
copper (ll) salt. After a while the solution becomes colourless.
8.1.1
8.1.2
8.1.3
8.2
(2)
How would the reading on the thermometer change as the reaction
proceeds? Write down INCREASES, DECREASES or REMAINS
THE SAME. Give a reason for the answer.
(2)
Refer to the reducing ability of aluminium to explain why the solution
becomes colourless.
(2)
Write down the balanced net IONIC equation for the reaction that
takes place.
(3)
The electrochemical cell shown below functions at standard conditions.
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V
Cu
Aℓ
salt bridge
Aℓ3+(aq)
Cu2+(aq)
8.2.1
Which electrode (Cu or Aℓ) is the anode?
(1)
8.2.2
Write down the cell notation for this cell
(3)
8.2.3
Calculate the emf of this cell
(4)
The salt bridge is now removed.
8.2.4
What will the reading on the voltmeter be? Give a reason for your
answer.
QUESTION 8
(4)
[17]
Nov 2011
The potential difference of a galvanic cell, measured experimentally by learners, is
COMPARED with its potential difference calculated at standard conditions.
They set up the galvanic cell shown below.
V
Cu
Pb
salt bridge
Cu2+(aq)
Pb2+(aq)
The voltmeter measures an initial reading of 0,3 V.
8.1
Write down the energy conversion that takes place in this cell.
(1)
8.2
State ONE function of the salt bridge.
(1)
8.3
Write down the half-reaction that takes place at the anode.
(2)
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8.4
In which direction do electrons flow in the external circuit when this cell
delivers a current? Write down only 'from Cu to Pb' or 'from Pb to Cu'.
(1)
8.5
Write down the balanced net (overall) cell reaction.
(3)
8.6
Is the cell reaction exothermic or endothermic?
(1)
8.7
Use the Table of Standard Reduction Potentials to calculate the initial
potential difference (emf) of the above cell at STANDARD CONDITIONS.
(4)
8.8
From the results obtained the learners conclude that the measured potential
difference differs from the calculated potential difference.
Give TWO possible reasons for this difference in values.
QUESTION 8
(4)
[17]
Mar 2011
The diagram below represents a galvanic (voltaic) cell functioning under standard
conditions with magnesium and silver as electrodes. A voltmeter connected across the
electrodes shows an initial reading of 3,17 V.
V
Mg(s)
Ag(s)
salt bridge
Mg2+(aq)
Ag+(aq)
8.1
State the energy conversion that takes place in this cell.
(2)
8.2
State TWO standard conditions under which this cell operates.
(2)
8.3
Identify the anode of this cell. Refer to the relative strength of reducing agents
to explain how you arrived at the answer.
(3)
8.4
Write down the cell notation (symbolic notation) of this cell.
(3)
8.5
Write down the balanced equation for the net (overall) cell reaction that takes
place in this cell. Omit the spectator ions.
(3)
8.6
How will an increase in the concentration of the Ag+ ions influence the current
that the cell delivers? Write down only INCREASES, DECREASES or
REMAINS THE SAME and explain the answer.
(3)
[16]
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QUESTION 9
Nov 2012
The simplified diagram below shows an electrolytic cell used at an electroplating
company to coat iron spoons with silver.
DC power source
Electrode Y
Iron spoons
Electrolyte X
9.1
Write down the energy conversion that takes place in this cell.
(1)
9.2
Direct current (DC) is used in this process. Give a reason why alternating
current (AC) is NOT used.
(1)
9.3
Which type of reaction (OXIDATION or REDUCTION) takes place at the
spoons?
(1)
9.4
Write down the:
9.4.1
Equation for the half reaction that takes place at electrode Y.
(2)
9.4.2
NAME or FORMULA of electrolyte X
(1)
9.5
Give a reason why the concentration of electrolyte X remains constant during
electroplating
(2)
9.6
Apart from the income generated, write down ONE major reason why the
company electroplates the spoons.
(1)
9.7
Write down the TWO major expenses for the company during the process.
(2)
[11]
QUESTION 9
Nov 2011
In the electrolytic cell, represented below, two CARBON RODS are used as electrodes
and a concentrated copper(II) chloride solution is used as electrolyte.
battery
Q
P
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CuCℓ2(aq)
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When the cell is functioning, a gas is released at electrode P, whilst electrode Q is
coated with a reddish brown layer.
9.1
Define the term electrolyte.
9.2
Write down a half-reaction to explain the observation made at:
(2)
9.2.1
Electrode P
(2)
9.2.2
Electrode Q
(2)
9.3
Which electrode, P or Q, is the cathode? Give a reason for the answer.
9.4
The carbon rods in the above cell are now replaced with COPPER RODS.
(2)
The following observations are made at electrode P:
 No gas is released.
 Its surface appears rough and eroded.
9.4.1
9.4.2
Refer to the RELATIVE STRENGTHS OF REDUCING AGENTS to
explain this observation.
This cell can be used for the refining of copper. Which electrode
(P or Q) will be replaced with impure copper during the refining
process?
(3)
(1)
[12]
QUESTION 9
Mar 2011
Electroplating is one of the uses of electrolysis. The diagram below shows an
electrolytic cell that can be used to plate a copper spoon with silver.
battery
copper spoon
electrode
AgNO3(aq)
9.1
Define the term oxidation in terms of electron transfer.
(2)
9.2
What type of half-reaction takes place at the copper spoon? Write down only
OXIDATION or REDUCTION.
(1)
Write down a half-reaction that explains the change that occurs on the surface
of the copper spoon during electrolysis.
(2)
Name the metal that is labelled 'electrode'.
(1)
9.3
9.4
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9.5
Give a reason why the concentration of the AgNO3(aq) remains constant
during electrolysis.
QUESTION 10
(2)
[8]
Nov 2012
The following half reactions take place when a non-rechargeable alkaline cell is in use:
Zn(s) + 2OH-(aq)  ZnO(s) + H2O(ℓ) + 2ē ……….
(1)
MnO2(s) + 2H2O(ℓ) + 2ē  Mn(OH)2(s) + 2OH- …… (2)
10.1
Write down the general name used for non-rechargeable cells.
(1)
10.2
Which ONE of the above equations (1 or 2) represents the half reaction that
takes place at the cathode? Give a reason for your answer.
(2)
10.3
Give a reason why the cell ‘dies’ after delivering current for a while
(1)
10.4
The emf of the alkaline cell is 1,5 V. The maximum electrical work that can be
done by this cell is 3 x 104 J.
Calculate the:
10.4.1
Cell capacity of this cell in A.h
(4)
10.4.2
Maximum constant current that this cell can deliver for 20 hours
(3)
[11]
QUESTION 10
Nov 2011
The simplified diagram of a membrane cell used in the chlor-alkali industry is shown
below. Gas A, gas B and compound C are the three major products formed during this
process. X and Y represent the two electrodes.
Gas A
Gas B
Membrane
Brine
Water
X
Y
Used salt solution
Compound C
Power supply
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10.1
Write down the function of the membrane in this cell.
(1)
10.2
Which electrode, X or Y, is connected to the positive terminal of the power
supply? Briefly explain how you arrived at the answer.
(2)
10.3
Write down the NAME or FORMULA of:
10.3.1
Gas A
(1)
10.3.2
Gas B
(1)
10.3.3
Compound C
(1)
10.4
Write down the balanced net (overall) cell reaction taking place in this cell.
10.5
The chlor-alkali industry is sometimes blamed for contributing to the
greenhouse effect. Briefly explain how the above cell contributes to the
greenhouse effect.
QUESTION 10
(3)
(2)
[11]
Mar 2011
A lead-acid battery (car battery) consists of six cells and has a battery capacity of 20
A∙h.
The half-reactions that take place in each cell and their respective standard reduction
potentials are represented below:
PbSO4(s) + H+(aq) + 2e-→ Pb(s) + HSO4-(aq)
Eθ = -0,36 V
PbO2(s) + 3H+(aq) + HSO4-(aq) + 2e-→ PbSO4(s) + 2H2O(ℓ)
Eθ = 1,7 V
10.1
Are car batteries primary or secondary batteries?
(1)
10.2
Write down the equation for the net (overall) cell reaction that takes place in
each cell of this battery.
(3)
Calculate the emf of the BATTERY, consisting of six cells, under standard
conditions.
10.3
10.4
10.5
(5)
Calculate the maximum time that this battery will be able to supply a constant
current of 5 A to an appliance connected to it. Assume that the capacity of the
battery remains constant.
State TWO environmental risks associated with the irresponsible disposal of
lead-acid batteries.
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NSC
QUESTION 11
Mar 2011
The flow diagram below represents processes used in the fertilizer industry.
Process
X
Air
Nitrogen
Hydrogen
Process Y
Process Z
Ammonia
Acid R
Ammonium sulphate
Write down:
11.1.1
The name of industrial process X
(1)
11.1.2
A balanced equation for process Y
(3)
11.1.3
The name of industrial process Z
(1)
11.1.4
A balanced equation for the preparation of ammonium sulphate
using acid R
(3)
The name of the type of reaction taking place in QUESTION 11.1.4
(1)
11.1.5
11.2
Ammonium nitrate is one of the most common compounds used as fertilizer.
11.2.1
11.2.2
Write down the NAME or FORMULA of the acid needed to prepare
ammonium nitrate from ammonia.
(1)
Write down TWO properties of ammonium nitrate that make it
Suitable for use as a fertilizer
(2)
[12]
QUESTION 11
Nov 2011
Nitric acid is used in the preparation of fertiliser. The flow diagram below shows the
three steps (A, B and C) in the industrial preparation of nitric acid.
NH3(g)
11.1
A
O2
Nitrogen(II) oxide
B
O2
NO2(g)
C
O2
HNO3(ℓ)
Write down the following:
11.1.1
Name of this industrial process in the preparation of nitric acid
(1)
11.1.2
Balanced equation for step B
(3)
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11.2
11.3
NH3(g) reacts with O2(g) to form two products in step A. One of the products
is nitrogen(II) oxide. Write down the NAME or FORMULA of the OTHER
product.
(1)
In step C, water is added to the reaction mixture. This step can be
represented by the following incomplete equation:
NO2(g) + ___ + H2O(ℓ) → HNO3(ℓ)
Copy the above incomplete equation into your ANSWER BOOK, fill in the
missing reactant and balance the equation.
11.4
(2)
A 50 kg bag of fertiliser is labelled as shown in the diagram below.
3 – 1 – 5 (30)
Calculate the mass of nitrogen present in this bag of fertiliser.
11.5
(3)
Uncontrolled use of fertiliser may cause excess fertiliser to run down into
streams and rivers, leading to eutrophication.
State ONE negative impact that eutrophication in water may have on humans.
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NSC
DATA FOR PHYSICAL SCIENCES GRADE 12
PAPER 1 (PHYSICS)
GEGEWENS VIR FISIESE WETENSKAPPE GRAAD 12
VRAESTEL 1 (FISIKA)
TABLE 1: PHYSICAL CONSTANTS/TABEL 1: FISIESE KONSTANTES
NAME/NAAM
Acceleration due to gravity
Swaartekragversnelling
Speed of light in a vacuum
Spoed van lig in 'n vakuum
Planck's constant
Planck se konstante
Coulomb's constant
Coulomb se konstante
Charge on electron
Lading op elektron
Electron mass
Elektronmassa
Permittivity of free space
Permittiwiteit van vry ruimte
Copyright reserved
SYMBOL/SIMBOOL
VALUE/WAARDE
g
9,8 m·s-2
c
3,0 x 108 m·s-1
h
6,63 x 10-34 J·s
k
9,0 x 109 N·m2·C-2
e
-1,6 x 10-19 C
me
9,11 x 10-31 kg
0
8,85 x 10-12 F·m-1
Please turn over
Fis
Wet
Telematika
Vraestelle
NSS
TABLE 2: FORMULAE/TABEL 2: FORMULES
MOTION/BEWEGING
v f  vi  a t
x  v i t  21 at 2 or/of y  v i t  21 at 2
 v  vi 
 v  vi 
x   f
 t or/of y   f
 t
 2 
 2 
v f 2  vi2  2ax or/of v f  v i  2ay
2
2
FORCE/KRAG
Fnet  ma
p mv
Fnet t  p  mv f  mv i
w  mg
WORK, ENERGY AND POWER/ARBEID, ENERGIE EN DRYWING
W  Fx cos 
1
K  mv 2 or/of
2
P
Ek 
U  mgh or/of EP  mgh
Wnet  K  K f  K i
1
mv 2
2
Wnet  Ek  Ekf  Eki
W
t
P  Fv
WAVES, SOUND AND LIGHT/GOLWE, KLANK EN LIG
vf
fL 
T
v  vL
fs
v  vs
sin  
1
f
E  hf or/of E  h
1
mv 2
2
1
hf  hf 0  mv 2
2
hf  W 0 
m
a
ELECTROSTATICS/ELEKTROSTATIKA
F 
kQ1Q 2
r2
V
d
kQ1Q2
U
r
Q
C=
V
E
Kopiereg voorbehou
E
kQ
r2
F
E
q
W
V
q
ε A
C= 0
d
c

Fis Wet
Vraestelle
NSS
ELECTRIC CIRCUITS/ELEKTRIESE STROOMBANE
R
1
1
1
 
 ...
R p R1 R 2
V
I
R s  R1  R 2  ...
emf ( ε ) = I(R + r)
qI t
emk ( ε ) = I(R + r)
W
Δt
P  VI
W = Vq
P
P I R
2
V2
P
R
W = VI  t
W = I2R  t
W=
V 2 Δt
R
ALTERNATING CURRENT/WISSELSTROOM
Pav erage  Vrms I rms or/of Pgemiddeld  Vwgk I wgk
I rms 
Vrms
Imax
I
/ I wgk  maks
2
2
V
V
 max / Vwgk  maks
2
2
Kopiereg voorbehou
Pav erage  I 2rms R or/of Pgemiddeld  I 2wgk R
Pav erage
2
2
Vwgk
Vrms
or/of Pgemiddeld 

R
R
Fis Wet
Vraestelle
NSS
GEGEWENS VIR FISIESE WETENSKAPPE GRAAD 12
VRAESTEL 2 (CHEMIE)
DATA FOR PHYSICAL SCIENCES GRADE 12
PAPER 2 (CHEMISTRY)
TABEL 1: FISIESE KONSTANTES/TABLE 1: PHYSICAL CONSTANTS
NAAM/NAME
Standaarddruk
Standard pressure
Molêre gasvolume by STD
Molar gas volume at STP
Standaardtemperatuur
Standard temperature
Lading op elektron
Charge on electron
SIMBOOL/SYMBOL
WAARDE/VALUE
p
1,013 x 105 Pa
Vm
22,4 dm3∙mol-1
T
273 K
e
-1,6 x 10-19 C
TABEL 2: FORMULES/TABLE 2: FORMULAE
c
n
m
M
n
V
of/or
m
MV
θ
θ
E sel  E katode
 E θanode / Eθcell  Eθcathode  Eθanode
c
of/or
q = It
θ
θ
E θsel  E reduksie
 E θoksidasie / E θcell  E reduction
 E θoxidation
W = Vq
of/or
θ
θ
θ
θ
E θsel  E θoksideermiddel  Ereduseermi
ddel / Ecell  Eoxidising agent  Ereducing agent
Kopiereg voorbehou
Fis Wet
Telematika
Vraestelle
NSS
TABEL 3: DIE PERIODIEKE TABEL VAN ELEMENTE
TABLE 3: THE PERIODIC TABLE OF ELEMENTS
Fr
0,9
0,7
133
87
Ra
Ac
17
(VII)
Ru
96
74
75
101
76
Rh
103
77
59
46
Pd
63,5
47
Ag
65
48
Cd
106
78
108
79
112
80
70
49
In
Sn
As
Sb
16
16
19
17
20
18
S
Cℓ
Ar
35,5
35
40
36
Br
Kr
80
53
84
54
I
Xe
127
85
131
86
At
Rn
Se
4,0
3,0
2,5
79
52
122
83
Te
128
84
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
179
181
184
186
190
192
195
197
201
204
207
209
58
59
60
61
62
63
64
65
66
67
68
69
70
71
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
140
141
144
150
152
157
159
163
165
167
169
173
175
90
91
92
93
94
95
96
97
98
99
100
101
102
103
Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Lr
238
Bi
Ne
32
34
75
51
119
82
Pb
3,5
3,0
2,1
31
33
73
50
115
81
Tℓ
Ge
F
O
2,8
Ga
28
32
P
2,4
Zn
Si
14
15
2,0
Cu
27
31
30
1,6
Ni
1,8
1,5
59
45
1,9
1,8
Co
29
12
14
N
9
2,5
56
44
18
(VIII)
4
10
8
2,1
Tc
Fe
1,8
1,8
1,6
1,5
55
43
28
Aℓ
C
7
1,9
Mo
Mn
27
1,7
92
73
52
42
26
1,9
91
72
25
B
6
2,5
5
11
13
2,2
Nb
16
(VI)
He
1,8
1,9
63,5
24
Cr
15
(V)
2
Simbool
Symbol
Cu
2,2
Zr
232
Kopiereg voorbehou
29
1,9
51
41
14
(IV)
Po
2,5
139
89
V
48
40
13
(III)
2,0
La
137
88
1,6
1,5
89
57
Ti
23
1,8
Y
1,4
45
39
Ba
226
12
1,9
Cs
88
56
0,9
0,7
86
55
Sr
Sc
22
1,6
40
38
1,0
0,8
Rb
Ca
21
1,3
K
39
37
11
Benaderde relatiewe atoommassa
Approximate relative atomic mass
Mg
24
20
1,0
0,8
23
19
10
1,8
9
12
1,2
0,9
7
11
9
Atoomgetal
Atomic number
Elektronegatiwiteit
Electronegativity
Be
8
1,8
4
1,5
1,0
1
3
Na
7
2,0
H
Li
6
KEY/SLEUTEL
1,2
2,1
1
5
1,6
4
1,7
3
1,8
2
(II)
2,2
1
(I)
Physical Sciences/P1
DBE/Feb. – Mar. 2011
5
NSC
TABEL 4A: STANDAARD-REDUKSIEPOTENSIALE
TABLE 4A: STANDARD REDUCTION POTENTIALS
F2(g) + 2e
⇌
2F
+ 2,87
e
⇌
Co2+
+ 1,81
H2O2 + 2H+ +2e
⇌
2H2O
+1,77
+ 8H+ + 5e
⇌
Mn2+ + 4H2O
+ 1,51
Cℓ2(g) + 2e
⇌
2Cℓ
+ 1,36
+ 14H+ + 6e
⇌
2Cr3+ + 7H2O
+ 1,33
O2(g) + 4H+ + 4e
⇌
2H2O
+ 1,23
2e
+
Pt2+ + 2e
⇌
Mn2+
⇌
Pt
+ 1,23
+ 1,20
Br2(ℓ) + 2e
⇌
2Br
+ 1,07
+
3e
⇌
NO(g) + 2H2O
+ 0,96
+
2e
⇌
Hg(ℓ)
+ 0,85
Ag+ + e
⇌
Ag
+ 0,80
+ 2H+ + e
⇌
NO2(g) + H2O
+ 0,80
Fe3+ + e
⇌
Fe2+
+ 0,77
+
2e
⇌
H2O2
+ 0,68
I2 +
2e
⇌
2I
+ 0,54
e
⇌
Cu
SO2 + 4H+ + 4e
⇌
S + 2H2O
+ 0,52
+ 0,45
2H2O + O2 + 4e
⇌
4OH
+ 0,40
Cu2+ + 2e
⇌
Cu
+ 0,34
+ 4H+ + 2e
⇌
SO2(g) + 2H2O
+ 0,17
Cu2+ + e
⇌
Cu+
+ 0,16
2e
⇌
Sn2+
+ 0,15
S + 2H+ + 2e
⇌
H2S(g)
+ 0,14
2e
⇌
H2(g)
Fe3+ + 3e
⇌
Fe
 0,06
Pb2+ + 2e
⇌
Pb
 0,13
Sn2+ + 2e
⇌
Sn
 0,14
Ni2+ + 2e
⇌
Ni
 0,27
2e
⇌
Co
 0,28
Cd2+ + 2e
⇌
Cd
 0,40
e
⇌
Cr2+
 0,41
Fe2+ + 2e
⇌
Fe
 0,44
3e
⇌
Cr
 0,74
Zn2+ + 2e
⇌
Zn
Co3+

MnO 4
2
Cr2O 7
MnO2 +

NO 3
+
Toenemende oksiderende vermoë/Increasing oxidising ability

NO 3
O2(g) +
4H+
2H+
Cu+
2
SO 4
+
4H+
Hg2+
Sn4+
2H+
Co2+
+
+
+
Cr3+
Cr3+
+
+
+
+ 2H2O
0,00
 0,76
⇌
H2(g) +
Cr2+ + 2e
⇌
Cr
 0,91
2e
⇌
Mn
 1,18
Aℓ3+ + 3e
⇌
Aℓ
 1,66
2e
⇌
Mg
 2,36
Na+ + e
⇌
Na
 2,71
Ca2+ + 2e
⇌
Ca
 2,87
2e
⇌
Sr
 2,89
Ba2+ + 2e
 2,90
Mn2+
Mg2+
+
+
Sr2+ +
2OH
 0,83
2e
2H2O +
⇌
Ba
e-
⇌
Cs
- 2,92
K+ + e
⇌
K
 2,93
Li+ + e
⇌
Li
 3,05
Cs+
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+
Toenemende reduserende vermoë/Increasing reducing ability
Halfreaksies/Half-reactions
Fis Wet
Vraestelle
NSS
TABEL 4B: STANDAARD-REDUKSIEPOTENSIALE
TABLE 4B: STANDARD REDUCTION POTENTIALS
Halfreaksies/Half-reactions
Li+ + e
⇌
Li
 3,05
K+ + e
⇌
K
 2,93
e
⇌
Cs
 2,92
Ba2+ + 2e
⇌
Ba
 2,90
2e
⇌
Sr
 2,89
Ca2+ + 2e
⇌
Ca
 2,87
Na+ + e
⇌
Na
 2,71
2e
+
Sr2+ +
⇌
Mg
 2,36
Aℓ3+ + 3e
⇌
Aℓ
 1,66
2e
⇌
Mn
 1,18
Cr2+ + 2e
⇌
Cr
Mg2+
Toenemende oksiderende vermoë/Increasing oxidising ability
Mn2+
+
+
 0,91
⇌
H2(g) +
Zn2+ + 2e
⇌
Zn
 0,76
3e
⇌
Cr
 0,74
Fe2+ + 2e
⇌
Fe
 0,44
e
⇌
Cr2+
 0,41
Cd2+ + 2e
⇌
Cd
 0,40
2e
⇌
Co
 0,28
Ni2+ + 2e
⇌
Ni
 0,27
Sn2+ + 2e
⇌
Sn
 0,14

⇌
Pb
 0,13
Fe3+ + 3e
⇌
Fe
2e
⇌
H2(g)
 0,06
0,00
S + 2H+ + 2e
⇌
H2S(g)
+ 0,14
2e
⇌
Sn2+
+ 0,15
Cu2+ + e
⇌
Cu+
+ 0,16
+ 4H+ + 2e
⇌
SO2(g) + 2H2O
+ 0,17
+
2e
⇌
Cu
+ 0,34
2H2O + O2 +
4e
⇌
4OH
+ 0,40
SO2 + 4H+ + 4e
⇌
S + 2H2O
+ 0,45
e
+ 0,52
2H2O +
Cr3+
+
Cr3+
Co2+
Pb
2+
2H+
Sn4+
2
SO 4
Cu2+
+
+
+ 2e
+
+
2OH
 0,83
2e
⇌
Cu

⇌
2I

+ 0,54
O2(g) + 2H+ + 2e
⇌
H2O2
+ 0,68
+
e
⇌
Fe2+
+ 0,77
+
e
⇌
NO2(g) + H2O
+ 0,80
+
e
⇌
Ag
+ 0,80
2e
⇌
Hg(ℓ)
+ 0,85
+ 4H+ + 3e
Cu+
+
I2 + 2e
Fe3+

NO 3
+
2H+
Ag+
Hg2+

NO 3
+
⇌
NO(g) + 2H2O
+ 0,96
2e
⇌
2Br
+ 1,07
Pt2+ + 2 e
⇌
Pt
+ 1,20
2e
⇌
Mn2+
O2(g) + 4H+ + 4e
⇌
2H2O
Br2(ℓ) +
MnO2 +
2
Cr2O 7
4H+
+
+ 2H2O
+ 1,23
+ 1,23
+
6e
⇌
2Cr3+
Cℓ2(g) +
2e
⇌
2Cℓ
+
8H+
5e
⇌
Mn2+
H2O2 +
2H+
e
⇌
2H2O
+1,77
e
⇌
Co2+
+ 1,81
F2(g) + 2e
⇌
2F
+ 2,87
+

MnO 4
14H+
+
+2
Co3+
+
+ 7H2O
+ 1,33
+ 1,36
+ 4H2O
+ 1,51
Toenemende reduserende vermoë/Increasing reducing ability
Cs+
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