exemplars caps gr12 sba2014

Western Cape Education Department

CURRICULUM DEVELOPMENT: FET

CAPSEXEMPLARS

SBA GRADE 12

PHYSICAL SCIENCES

2014

Physical Sciences WCED Gr12 CAPS Exemplar Jan 2013

EXEMPLARS

CAPS GRADE 12

1. GENERAL PRINCIPLES

1.1 Teachers should do the experiment before they design the worksheet for

the experiment that their learners will do.

1.2 The teacher should develop a marking memorandum that is a good guide

to mark each learner’s experiment.

1.3 The experiment should be scheduled to commence after the subject

content is taught in the classroom.

1.4 Learners should do the experiment on their own.

1.5 Theoretical questions on content should not be part of the experiment.

However, they have value and should be asked as informal assessment or

as an integral part of a control test or an examination.

1.6 Mark totals for practical tasks should be converted to a mark out of 15,

correct to the first decimal place, for transfer to the mark schedule.

2. EXPERIMENT 1 EXAMPLE OF A WORKSHEET: See Annexure A, page 20

2.1 Aim: To prepare different esters and identify the esters by their smell.

The following experiments have to be done:

Experiment 1(a): Prepare methyl ethanoate and identify its smell

Experiment 1(b): Prepare ethyl ethanoate and identify its smell

Experiment 1(c): Prepare pentyl ethanoate and identify its smell

Experiment 1(d): Prepare methyl salicylate and identify its smell

Experiment 1(e): Prepare ethyl salicylate and identify its smell

Experiment 1(f): Prepare pentyl salicylate and identify its smell

These experiments can be combined into one experiment as

illustrated at 2.2.

Copyright reserved Please turn over2


2.2 Write Up for Experiment 1(a) to 1(f): [27 marks]

Aim: To prepare the following esters and to identify each of their smells.

Methyl ethanoate Ethyl ethanoate Pentyl ethanoate

Methyl salicylate Ethyl salicylate Pentyl salicylate

All WCED schools should use the following headings for the

Write Up and should adhere to the mark weighting and

distribution for each heading.

MARKING MEMORANDUM:2.2.1 PLANNING [9 marks]

The following marking scheme should be used.

(a) Naming or Drawing apparatus (3)

(Including chemicals)

None named or

drawn.

Some named or

Drawn or

Incorrect.

to

All named or

Drawn & correct.

(b) Identification of variables (3)

(Award 1 mark for each correct variable and zero

marks if none are correct.)

(c) Collecting , recording and evaluating data (3)

(Award zero marks if none are described or appropriate)

[9]

2.2.2 RESULTS [15 marks]




(a) Table (9 marks) (One table summarizing all the results):

No table is provided OR Table is incorrect/inappropriate (0)

Table heading is appropriate (1)

Column headings are appropriate (2)

Data is appropriate , accurate and correct (3)

Data was evaluated or measurements are repeated

at least three times (3)

Balanced chemical equation for each reaction (6)

(One mark for each correctly balanced equation.)

[15]

2.2.3 CONCLUSION or FINDINGS [3 marks]

Results are correctly interpreted (3)

[3]

TOTAL MARK /27/

2.3 METHOD [0 marks]

Although the method is provided in textbooks, a suggested method is

provided below.

SAFETY:

1. Alcohols are flammable and organic acids are corrosive. Sulphuric acid

is poisonous, dangerous and corrosive. It burns body tissue and may

be fatal if swallowed.

2. Methanol, ethanol and pentanol have flashpoints of 12 oC, 16,6 oC and

49 oC respectively i.e. the lowest temperature at which their vapours

ignite. These temperatures are lower than the boiling point of water

which is 100 oC.



3. For more information on the hazards associated with methanol,

ethanol, ethanoic acid (acetic acid (glacial)) and ethyl ethanoate please

consult your laboratory manual.

4. Solutions containing flammable liquids must not be heated in a test

tube. Use a cotton wool plug to prevent alcohol from spilling and heat

the test tube containing the solution by using a water bath. Keep the

test tube vertical in the water bath.

5. All glassware used in this experiment must be heat resistant.

6. Do not overheat the reaction mixture. It must not boil.

7. Do not place your nose directly over the test tube to smell the ester

produced while the water bath is being heated.

8. All chemicals are hazardous. Wear safety goggles and gloves when

handling chemicals

9. Ensure that all gas taps are closed before and after the use of Bunsen

burner(s).

Suggested method:

Step 1:

Make a water bath by pouring 50 cm3 of water into a 100 cm3 beaker.

Place the beaker on wire gauze that rests on a tripod stand. Place a

Bunsen burner under the gauze wire.

Step 2:

Add 10 drops of ethanol to 10 drops of ethanoic acid (acetic acid (glacial))

in a dry test tube. Add 5 to 10 drops of concentrated sulphuric acid to this

mixture.

Step 3:

Place cotton wool in the mouth of the test tube. Lower the test tube into

the water bath using tongs.

Step 4:

Heat the water in the water bath using the Bunsen burner. Cool the test

tube under running water.



Step 5:

Pour the contents of the test tube into a 100 cm3 beaker containing 50 cm3

of cold water. Now identify the smell of the ester by wafting the escaping

gas from the test tube towards your nose using your hand.

Repeat steps 1 to 5 for the other esters. In the preparations involving

salicylic acid, Step 2 is as follows: Mix 1 g of salicylic acid with 2 drops of

concentrated H2SO4 and 2 cm3 of the alcohol.

NOTES:

The smell of carboxylic acid may interfere with the smell of the

ester formed. If this is the case, make a Na2CO3(aq) solution of

concentration 0,5 mol.dm-3, and then pour the contents of the test

tube in Step 4 into 50 cm3 of the Na2CO3 solution. The Na2CO3

neutralises the ethanoic acid.

In general, esters are not miscible with water. When added to water

two layers form, one is water and the other is the ester. This allows

the ester to be separated from the water for identification.

2.4 MARK CONVERSION

The mark out of 27 is reduced to a mark out of 15, expressed correct to

the first decimal place, for transfer to the mark schedule.



3. EXPERIMENT 2

3.1 Aim: To determine the concentration of a solution of sodium hydroxide

using a standard solution of oxalic acid.

In this experiment a standard solution of oxalic acid of concentration

0,06 mol.dm-3 and a solution of sodium hydroxide of concentration

approximately 0, 03 mol.dm-3, is prepared in advance for the titration by

the teacher.

3.2 Write Up for Experiment 2: Use a standard solution of oxalic acid of concentration 0,06 mol. dm-3 to determine the concentration of a sodium hydroxide solution of concentration approximately 0,03 mol.dm-3 . [30 marks]







(Including chemicals)

None named or

Drawn.

Some named or

Drawn or

Incorrect.

to

All named or

Drawn & correct.





[6]



(a) Table (9 marks):


Heading is appropriate (1)




[9]

CALCULATION OF CONCENTRATION OF NAOH

If no calculation or calculation incorrect (0)

Appropriate balanced equation (1)

Correct formula: LHS = RHS (mol ratio) (2)

Substitution: (2)

[5]

SLIDING SCALE [10]

[NaOH] obtained is marked with a sliding scale (10)

The following sliding scale will be used to assess the accuracy and correctness

of the [NaOH] solution you obtained.


0 1 2 3 4 5 6 7 8 9 9 8 7 6 5 4 3 2 1 0

2%4%6%8%10%12%20%30%50%100% 2% 4% 6% 8% 10% 12% 20% 30% 50% 100%

%age Error

Correct value (10 m

arks) m

arks)

Values below correct value Values above correct valueMarks

Mark


[10]

Total mark: /30/3.3 Method


provided below.

SAFETY:

1. Oxalic acid is corrosive. It can be fatal if swallowed.

2. Sodium hydroxide is poisonous, harmful if inhaled, burns the skin

and it may be fatal if swallowed.

3. All chemicals are hazardous. Please consult your laboratory

manual for more information about why oxalic acid, sodium

hydroxide and sulphuric acid are hazardous.

4. Wear safety goggles and gloves when handling chemicals.

Suggested method:

Set up the apparatus that will be used to do this experiment. Use a 25 cm3

pipette to transfer 25 cm3 of the oxalic acid provided to a 250 cm3

Erlenmeyer flask. Add 5 drops of phenolphthalein indicator to the oxalic

acid in the Erlenmeyer flask. Fill the burette up to the 50 cm3 mark with the

sodium hydroxide solution provided. Titrate until the colour of the solution

turns pink. Record your results. Repeat the experiment at least three

times.

3.4 MARK CONVERSION

The mark out of 30 is reduced to a mark out of 15, expressed correct to

the first decimal place, for transfer to the mark schedule.



4. EXPERIMENT 3

This experiment consists of two parts viz.

4.1 Part l

Aim: To determine the internal resistance of a battery

Part ll

Aim: To determine the equivalent resistance of:

(a) Resistors in series

(b) Resistors in parallel

4.2 Write Up for Experiment 3 - Part l: To determine the internal resistance of a battery. [40 marks]







None named or

Drawn/Inappropriate

Some named or

Drawn or

Incorrect.

Or

All named or

Drawn &

correct.








[9]









[9]

(b) Graph (9 marks)

No graph is provided OR Graph is incorrect/inappropriate (0)


Scale is appropriate (2)

Axes correctly labelled (2)

Appropriate type of graph chosen (2)

Points plotted correctly (2)

[9]

(c) Accuracy of the answer (10 marks)

The answer for r is marked with a sliding scale


0 1 2 3 4 5 6 7 8 9 9 8 7 6 5 4 3 2 1 0

2%4%6%8%10%12%20%30%50%100% 2% 4% 6% 8% 10% 12% 20% 30% 50% 100%

%age Error

Correct value (10)

marks)


Mark


[10]

4.2.3 EXPLAINING HOW THE RESULTS WERE OBTAINED [3 marks]

No explanation is

given

Explanation is

incomplete

Or

Complete

explanation is

given.

[3]

Total mark for Part l: /40/4.3 METHOD


provided below.

SAFETY:

1. Prevent electrical shock. Use a torch cell.

2. Do not use mains voltage or operate any device that needs mains

voltage to work.

Suggested method:

Set up a circuit as follows:

Take a reading on the voltmeter and ammeter when the switch S is open.


A

V

S


Close the switch S. Set the rheostat at various resistance values starting

at a low resistance. Record the ammeter and voltmeter reading in each

case.

Repeat the experiment at least three times.

Record your results in a table and in a graph of V (voltmeter readings)

versus I (ammeter readings).

Measure the gradient of the graph. Write your answer as a positive value.

This is the internal resistance of the battery.

4.4 Write Up for Experiment 3 - Part ll: To determine the equivalent resistance of:(a) (i) Two resistors in series [36 marks]

(ii) Three resistors in series [10 marks](iii) Four resistors in series [10 marks)

(b) (i) Two resistors in parallel [36 marks](ii) Three resistors in parallel [10 marks](iii) Four resistors in parallel [10 marks]

All WCED schools should use the following headings for the Write Up and

should adhere to the mark weighting and distribution for each heading.

PART ll (a) (i): To determine the equivalent resistance of Two resistors in series.




None named or

Drawn.

Some named or

Drawn or

All named or

Drawn & correct.



Incorrect.

to






[9]









[9]

(b) Calculations (Calculated and measured values)

None done OR Are incorrect OR Are inappropriate (0)

Incomplete OR Partly correct (1 to 3 marks) (3)

Complete and correct (2)

[5]

(c) Accuracy of the answer obtained through measuring (10 marks)

Use the sliding scale


0 1 2 3 4 5 6 7 8 9 9 8 7 6 5 4 3 2 1 0

2%4%6%8%10%12%20%30%50%100% 2% 4% 6% 8% 10% 12% 20% 30% 50% 100%

%age Error

Correct value (10m

arks) m

arks)


Mark


[10]

4.4.3 EXPLAINING COMPARISON BETWEEN EXPERIMENTAL AND

THEORETICAL ANSWERS [3 marks]

No explanation is

given

Explanation is

incomplete

Or

Complete

explanation is

given.

[3]

Total mark for experiment 3 (a) (i): /36/

4.5 METHOD (Experiment 3 (a) (i))


provided below.

SAFETY:

1. Prevent electrical shock. Use a torch cell.

2. Do not use mains voltage or operate any device that needs mains

voltage to work.

Suggested method:

Set up a circuit as follows, using two resistors in series:



Close the switch S and write down the reading on the ammeter and

voltmeter. Use these readings to calculate the total resistance of the two

resistors in series. Calculate the theoretical value of their total resistance.

Repeat this part of the experiment three times.

PART ll (a) (ii): To determine the equivalent resistance of three resistors in series.

MARKING MEMORANDUM:(c) Accuracy of the answer obtained through measuring (10)

Use the same sliding scale in 4.4.2 (c)

[10]

Total mark for experiment 3 (a) (ii): /10/

PART ll (a) (iii): To determine the equivalent resistance of four resistors in series.

MARKING MEMORANDUM:(c) Accuracy of the answer obtained through measuring (10)

Use the same sliding scale in 4.4.2 (c)

[10]

Total mark for experiment 3 (a) (iii): /10/Total mark for experiment 3 (a): /56/


A

S

V


4.6 Write Up for Experiment 3 - Part ll (b): To determine the equivalent resistance of:

(b) (i) Two resistors in parallel [36 marks](ii) Three resistors in parallel [10 marks](iii) Four resistors in parallel [10 marks]

This experiment is similar to Part ll (a). The main difference is that the

resistors are now connected in parallel. Otherwise the Method, the Write

Up and the mark allocation is the same.

4.7 MARK CONVERSION

Experiment 3 Part l is assessed out of 40 marks. Part ll (a) and (b) are

assessed out of 56 marks. The total mark obtained,

viz. 40 + (2 x 56) = 152, is reduced to a mark out of 15, expressed correct

to the first decimal place for transfer to the mark schedule.



5. EXPERIMENT 4Aim: To verify that momentum is conserved during an explosion.

5.1 Write Up for Experiment 4: To verify that momentum is conserved during an explosion if the:

(a) Two trolleys carry the same mass [26](b) One trolley carries twice the mass of the other trolley [10](c ) One trolley carries a mass that is three times that of the other

trolley [10]

The Write Up is the same as that for Experiment 3 – Part ll (a) [56 marks]

5.2 METHOD


provided below.

SAFETY:

Suggested method

Take two identical trolleys and place a brick of the same mass m on each

of them. At least one of the trolleys must have a spring plunger. Place the

trolleys on a level horizontal frictionless surface. Clamp two wooden

blocks at equal distances x from each trolley. Release the knob.


x xm mPress the knob


Each trolley must strike the wooden block at the same time t. Repeat

three times.

Repeat the experiment by placing another brick on one trolley.

Repeat the experiment by placing another brick on the trolley that has the

two bricks.

Record your results in a table.

5.3 MARK CONVERSION

The total mark out of 56 is reduced to a mark out of 15, expressed correct

to the first decimal place for transfer to the mark schedule.

ANNEXURE A



EXAMPLE OF A CAPS GRADE 12 WORKSHEET:

SCHOOL: …………………………………. DATE: ……………………………SBA: PRESCRIBED EXPERIMENT: PHYSICAL SCIENCES NAME OF LEARNER: ………………………… GRADE: ……………………

KNOWLEDGE AREA: Chemical Change GROUP: ……………………TOPIC: Acids and Bases

DUE DATE: ………………………………. TOTAL MARK: ………/30

AIM: To determine the concentration of a solution of sodium hydroxide

using a standard solution of oxalic acid.

In this experiment you will be provided with:

A standard solution of oxalic acid of concentration 0,06 mol.dm-3

A sodium hydroxide solution of concentration approximately

0,03 mol.dm-3

METHOD:

Suggested method:

Set up the apparatus that will be used to do this experiment. Use a 25 cm3

pipette to transfer 25 cm3 of the oxalic provided to a 250 cm3 Erlenmeyer

flask. Add 5 drops of phenolphthalein indicator to the oxalic acid in the

Erlenmeyer flask. Fill the burette up to the 50 cm3 mark with the sodium

hydroxide solution provided. Titrate until the colour of the solution turns

pink. Record your volume readings. Repeat the experiment at least three

times.

INSTRUCTIONS



(a) Read and understand the method to:

Determine the concentration of the sodium hydroxide solution using

the standard solution of oxalic acid provided by your teacher.

(b) You will be penalised if:

o The work you submit is not your own

o You do not hand in this assessment task by the due date

(c) Report your investigation using the headings below (marks are written in

brackets)

PLANNING THE INVESTIGATION [6 marks]

The following should be reported on:

(a) Apparatus (3)

(Naming or drawing each item of apparatus used)

(b) Data (3)

(Collecting, recording and evaluating data)[6]

RESULTS [24 marks]

(a) Table (9)(Recording results in a table)

(b) Calculations (5)[14]

SLIDING SCALE (10)(Marking the [NaOH] with a sliding scale)

[10]

Total mark: /30/



NOTES FOR THE TEACHER

(a) Safety:1. Oxalic acid is corrosive. It can be fatal if swallowed.

2. Sodium hydroxide is poisonous, harmful if inhaled, burns the skin

and it may be fatal if swallowed.

3. All chemicals are hazardous. Please consult your laboratory

manual for more information about why oxalic acid and sodium

hydroxide are hazardous.

4. Wear safety goggles and gloves when handling chemicals

(b) Accuracy of the results:

In this experiment accuracy should be exploited to achieve a spread of marks. Accuracy can be judged by the value of the [NaOH] which will be marked with the sliding scale.

Do the following to obtain accurate results: All glassware/apparatus used must be clean The measuring flask should only be held at its mouth Wash the beaker that contained the oxalic acid solution with

distilled water. Pour this solution into the measuring flask The burette must be greased appropriately so that it works and

does not leak when the tap is opened and closed. NaOH absorbs water and CO2 from the air. This changes the

concentration of the NaOH(aq). Make a fresh sample for the titration but use it immediately.

Do not exceed the endpoint of the titration

(c) Other methods:

The double burette method can also be used.

(d) Assessment:

Each learner should do this investigation on their own.Do not assess group work.Each learner should sign a declaration of authenticity.


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