Notesale: Turn your study into money

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ANSWERING TIPS FOR CHEMISTRY PAPER 63
Prepared by Mr Yow
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For eg, if the question says “give two observations besides
the temp change”, don’t include temperature change in your answer
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Check for contradictions within your answer
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3
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A common mistake: “gas is given off” or “copper is deposited”
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4
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When drawing labelled diagrams:
• ensure diagram is drawn in the space given and is labelled
• diagram for gas measurement – make sure that the gas can’t escape!! For eg, don’t
draw a gas syringe with the plunger much smaller than the syringe barrel – this’s a
common error!

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You will not
get a mark if you use a ruler for plotting a best fit curve
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Points on
the graph should be clearly marked as crosses or encircled dots
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7
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For eg, the use of graphite :
This is the answer given by a student – Graphite is used in electrolysis
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8
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For eg, a chemical test for water is turns anhydrous copper(II) sulfate from white to blue
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9
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You don’t need to do this for the ammonium ion
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Please REMEMBER!!

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At this time, you should know the results of these tests for HCl and Cl2 gases (please
see pg 20 of Chapter 1 Acid, Base & Salt module)

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Students always omit the sentence in bold!

12
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A common mistake is to say that the powdered metal, when reacted with acid, gives
off more gas than larger lumps of the same amount of metal
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The difference is the
powdered metal, when reacted with acid has a higher ROR!!

13
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The same amount of reactants is the important factor!

14
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Remember that the ROR is
decreasing with time as the reaction proceeds because ROR =

15
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/0
1"-$ 1/2$&

What does the symbol “aq” mean?
Answer “aqueous” alone isn’t enough to fetch you 2 marks! You must include
Solution ✔

formed when solute dissolved in water ✔

Additional info: bromine at room temperature is liquid but once it’s displaced from
KBr (aq) by Cl2 (g) {see pg 11 of Yr10 Chapter 4 Periodic Table module} then bromine
will be in aqueous state
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REMEMBER: Always use the colours given in the syllabus for Testing for Ions
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Cr3+ is green precipitate in little aqueous sodium hydroxide but it’s grey green
precipitate in a little aqueous ammonia
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18
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They
should be made up of narrow blocks of equal width that do not touch!!

19
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Disadvantage: The speed of discharging the solution is very slow
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Disadvantage: Inaccurate in measuring the volume of solution/ liquid
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Reason: More accurate in measuring the volume of solution // more accurate in
measuring the time // reduce heat loss to the surrounding / cover the plastic cup
with a lid (measuring the change in temperature) // precise thermometer
(digital)
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Suggest improvement(s) to reduce the source
of error(s)”
The answer for this question will depend on the type of experiment given!
Error: Use of measuring cylinder // Use of any metal container // Imprecise
thermometer used // Experiment only done once // Reading taken every 1
minute
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Answer depends on the experiment!!!
Example of this is, Sri KL Year 10 Year End Exam Paper 6, 2016; will send it to you
ONLY if you are interested!!

21
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The pencil is obviously
insoluble in the solvent!
It should be worded as The pencil mark or the pencil line is insoluble in the solvent
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For the last question, no
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Your first statement (first step) of answer is very important!
If you are unsure of what volume of solution/liquid or mass of a solid to specify, use
an unknown variable; for eq, V1 cm3 or X gram respectively
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