SENIOR SECONDARY IMPROVEMENT PROGRAMME 2013
GRADE 12
PHYSICAL SCIENCES
LEARNER NOTES
The SSIP is supported by 1
(c) Gauteng Department of Education, 2013
, TABLE OF CONTENTS
LEARNER NOTES
SESSION TOPIC PAGE
Chemical Equilibrium
Electrolytic and galvanic cells
Consolidation exercises – mechanics and matter, and
materials
Consolidation exercises – sound, Doppler effect and light
Consolidation exercises – organic molecules and their
reactions
Consolidation exercises – rates, chemical equilibrium and
electrochemistry
1. Electrostatics - Grade 11 revision
2. Electricity – Grade 11 revision
Electrodynamics – motors and generators and alternating
current.
2
(c) Gauteng Department of Education, 2013
,GAUTENG DEPARTMENT OF EDUCATION SENIOR SECONDARY INTERVENTION PROGRAMME
PHYSICAL SCIENCES GRADE 12 SESSION 8 (LEARNER NOTES)
SESSION 8
TOPIC: CHEMICAL EQUILIBRIUM
Learner Note: Please understand and learn the factors affecting the rate of a reaction very
well before attempting this section on chemical equilibrium. The only factors affecting
chemical equilibrium are temperature, concentration and pressure.
SECTION A: TYPICAL EXAM QUESTIONS
QUESTION 1: 5 minutes
Consider the following equilibrium reaction:
N2 (g) + 3 H2(g) 2NH3 (g) H< 0
9 mol of N2 and 15 mol of H2 are pumped into a 500cm3 container at room temperature.
The temperature of the gas mixture is now raised to 405°C resulting in 8 mol NH3 being
present at equilibrium.
Calculate the value of Kc at 405°C0 [6]
QUESTION 2: 18 minutes
Consider the following reaction:
2SO2 (g) + O2 (g) 2SO3 (g) H < 0
A graph of the AMOUNT of SO3 (g) was plotted against time as shown below:
2.1 How does the rate of the forward reaction compare to the rate of the reverse
reaction during the following intervals?:(Write down only GREATER THAN,
EQUAL TO or LESS THAN.)
2.1.1 OA (1)
2.1.2 BC (1)
2.1.3 DE (1)
3
(c) Gauteng Department of Education, 2013
, GAUTENG DEPARTMENT OF EDUCATION SENIOR SECONDARY INTERVENTION PROGRAMME
PHYSICAL SCIENCES GRADE 12 SESSION 8 (LEARNER NOTES)
2.2 Initially 8,0 moles of SO2 (g) and x moles of O2 (g) are placed in a 2,0 dm3 empty
container and sealed at a specific temperature. At equilibrium 6,0 moles of SO 3
(g) are present in the container. If the KC value of the above equilibrium at this
temperature is 9, calculate x, that is, the initial amount of O2 (g) that was placed
in the container. (6)
2.3 If the changes in the graph from B to D are due to changes in the
TEMPERATURE, at which points (B, C or D) will the temperature be the
lowest? (1)
2.4 Give an explanation for the answer to 2.3. (2)
2.5 At which point (B, C or D) will the KC value be the greatest? (1)
2.6 Give an explanation for the answer to 2.5. (2)
2.7 If the changes in the graph from B to D are due to PRESSURE changes, at
which point (B, C or D) will the pressure be the lowest? (1)
2.8 Give an explanation for the answer to 2.7. (2)
[18]
QUESTION 3: 7 minutes
3. A mixture of 5 moles of H2 (g) and 10 moles of I2 (g) is placed in a 5dm3 container and is
allowed to reach equilibrium at 448oC. The equation for the equilibrium reaction is:
H2 (g) + I2 (g) 2HI(g)
At equilibrium the concentration of the HI(g) is equal to 1,88 mol.dm-3.
3.1 Calculate the value of Kc at 448oC. (6)
3.2 While the system is in equilibrium, H2 (g) is added to it. Explain by using Le Chatelier’s
principle how the addition of H2 (g) influences the number of moles of HI(g) when a new
equilibrium has been established. Assume that the temperature is kept constant (3)
[9]
QUESTION 4: 20 minutes (Physical Sciences Paper 2 DoE Feb – March 2010)
Combustion in air at high temperatures produces oxides of nitrogen of which nitrogen
dioxide (NO2(g)), is the most common. Natural sources of nitrogen dioxide include
lightning and the activity of some soil bacteria. These natural sources are small compared
to emissions caused by human activity.
NO2 can irritate the lungs and cause respiratory infection. When NO 2(g) dissolves in
rainwater in air it forms nitric acid which contributes to acid rain.
4.1 State TWO human activities that contribute to high nitrogen dioxide levels in the
atmosphere. (2)
4.2 Write a balanced equation to show how nitric acid forms from nitrogen dioxide in air.(2)
4
(c) Gauteng Department of Education, 2013
GRADE 12
PHYSICAL SCIENCES
LEARNER NOTES
The SSIP is supported by 1
(c) Gauteng Department of Education, 2013
, TABLE OF CONTENTS
LEARNER NOTES
SESSION TOPIC PAGE
Chemical Equilibrium
Electrolytic and galvanic cells
Consolidation exercises – mechanics and matter, and
materials
Consolidation exercises – sound, Doppler effect and light
Consolidation exercises – organic molecules and their
reactions
Consolidation exercises – rates, chemical equilibrium and
electrochemistry
1. Electrostatics - Grade 11 revision
2. Electricity – Grade 11 revision
Electrodynamics – motors and generators and alternating
current.
2
(c) Gauteng Department of Education, 2013
,GAUTENG DEPARTMENT OF EDUCATION SENIOR SECONDARY INTERVENTION PROGRAMME
PHYSICAL SCIENCES GRADE 12 SESSION 8 (LEARNER NOTES)
SESSION 8
TOPIC: CHEMICAL EQUILIBRIUM
Learner Note: Please understand and learn the factors affecting the rate of a reaction very
well before attempting this section on chemical equilibrium. The only factors affecting
chemical equilibrium are temperature, concentration and pressure.
SECTION A: TYPICAL EXAM QUESTIONS
QUESTION 1: 5 minutes
Consider the following equilibrium reaction:
N2 (g) + 3 H2(g) 2NH3 (g) H< 0
9 mol of N2 and 15 mol of H2 are pumped into a 500cm3 container at room temperature.
The temperature of the gas mixture is now raised to 405°C resulting in 8 mol NH3 being
present at equilibrium.
Calculate the value of Kc at 405°C0 [6]
QUESTION 2: 18 minutes
Consider the following reaction:
2SO2 (g) + O2 (g) 2SO3 (g) H < 0
A graph of the AMOUNT of SO3 (g) was plotted against time as shown below:
2.1 How does the rate of the forward reaction compare to the rate of the reverse
reaction during the following intervals?:(Write down only GREATER THAN,
EQUAL TO or LESS THAN.)
2.1.1 OA (1)
2.1.2 BC (1)
2.1.3 DE (1)
3
(c) Gauteng Department of Education, 2013
, GAUTENG DEPARTMENT OF EDUCATION SENIOR SECONDARY INTERVENTION PROGRAMME
PHYSICAL SCIENCES GRADE 12 SESSION 8 (LEARNER NOTES)
2.2 Initially 8,0 moles of SO2 (g) and x moles of O2 (g) are placed in a 2,0 dm3 empty
container and sealed at a specific temperature. At equilibrium 6,0 moles of SO 3
(g) are present in the container. If the KC value of the above equilibrium at this
temperature is 9, calculate x, that is, the initial amount of O2 (g) that was placed
in the container. (6)
2.3 If the changes in the graph from B to D are due to changes in the
TEMPERATURE, at which points (B, C or D) will the temperature be the
lowest? (1)
2.4 Give an explanation for the answer to 2.3. (2)
2.5 At which point (B, C or D) will the KC value be the greatest? (1)
2.6 Give an explanation for the answer to 2.5. (2)
2.7 If the changes in the graph from B to D are due to PRESSURE changes, at
which point (B, C or D) will the pressure be the lowest? (1)
2.8 Give an explanation for the answer to 2.7. (2)
[18]
QUESTION 3: 7 minutes
3. A mixture of 5 moles of H2 (g) and 10 moles of I2 (g) is placed in a 5dm3 container and is
allowed to reach equilibrium at 448oC. The equation for the equilibrium reaction is:
H2 (g) + I2 (g) 2HI(g)
At equilibrium the concentration of the HI(g) is equal to 1,88 mol.dm-3.
3.1 Calculate the value of Kc at 448oC. (6)
3.2 While the system is in equilibrium, H2 (g) is added to it. Explain by using Le Chatelier’s
principle how the addition of H2 (g) influences the number of moles of HI(g) when a new
equilibrium has been established. Assume that the temperature is kept constant (3)
[9]
QUESTION 4: 20 minutes (Physical Sciences Paper 2 DoE Feb – March 2010)
Combustion in air at high temperatures produces oxides of nitrogen of which nitrogen
dioxide (NO2(g)), is the most common. Natural sources of nitrogen dioxide include
lightning and the activity of some soil bacteria. These natural sources are small compared
to emissions caused by human activity.
NO2 can irritate the lungs and cause respiratory infection. When NO 2(g) dissolves in
rainwater in air it forms nitric acid which contributes to acid rain.
4.1 State TWO human activities that contribute to high nitrogen dioxide levels in the
atmosphere. (2)
4.2 Write a balanced equation to show how nitric acid forms from nitrogen dioxide in air.(2)
4
(c) Gauteng Department of Education, 2013
