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PAPER 3 (2014)

1. Properties of oxide for period 3 elements(structure/planning) 2. Type of electrode (planning)

3. Hardness of pure metal and alloy.(Structure)

4. Rate of reaction ; size of reactant (Structure)

5. Rusting of iron nail(Structure/planning)

6. Effect of temperature on rate of reaction;markX(Planning)

7. Compare and contrast soap and detergent(Planning)

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Diagram 2.0

Rajah 2.0

Refering to the dialog in diagram 2.0, plan a laboratory experiment to investigate the

effect of type of electrode at anode. Your planning should include the following

aspects:

(a) Aim of the experiment.

- To investigate the effect of type of electrode at anode.

(b) All the variables.

MV: Type of electrode

RV: Products at anode

FV: Concentration of electrolyte

(c) Statement of the hypothesis

-When C electrodes used in electrolysis of CuSO4, gas bubbles released at

anode and when used Cu electrode, anode become thinner.

(d) List of materials and apparatus

-Copper electrode, Carbon electrode, battery, connecting wire, beaker, 50 cm3of 0.5

mol dm-3

copper(II) sulphate.

When you repeat the experiment using copper electrodes

to replace the carbon .What is the observation at anode,

Ali?

Anode become

thinner, sir

I observed the gas bubbles are released at anode when I used

carbons as electrode during electrolysis of CuSO4 sir

-Dissolve in acid -Doesnt dissolve in alkali

Basic oxide

-Dissolve in acid & alkali

Amphoteric oxide

-Doesnt dissolve in acid -Dissolve in alkali

-Acidic oxide

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(e) Procedure for the experiment

- CuSO4 is poured into beaker.

- 2 carbon electrodes are immersed into solution and connected to battery

- Record observation at anode

- Step 1-4 is repeated using Cu electrode.

(f) Tabulation of data

Type of electrode Products at anode

Copper

Carbon

Type of block

Diameter of dent

Mass of weight

Bronze produced smaller diameter of dent than copper

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-Copper is soft& weak

-Bronze is harder

-When 1kg weight is dropped on steel ball, diameter of dent produced on bronze is smaller.

-Tin -Duralumin -Brass

-Orange-red spot (rust) formed on iron spoon and no changes on steel spoon

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Diagram 1 shows the set up of the apparatus used in the experiment

(b) State all the variables in this experiment

MV:Size of zinc

RV:Rate of reaction

FV:Mass of Zn/Concentration of HCl

(c) State two observation that you could obtained from the experiments I -Gas bubbles released/water level in burette decreases/Zn metal dissolves

(d) What is the inference can you make based on the result from both experiments? -Smaller size of zinc increase total surface area exposed to collision with H

+.

(e) Big size of ice cube (5 g) takes longer times to melt compare small size of ice cube(5g)

at room temperature. Explain why

-Small size ice cube has more total surface area exposed

-absorb more heat

-melt more faster.

A student carried out the experiments to study the factors that affect the rate of reaction

between zinc and hydrochloric acid in the laboratory. The student measured the volume of

gas liberated using a burette at regular intervals of 30 seconds.

Diagram 1 Table 1 shows the experimental conditions carried out by the student.

Experiment Experimental condition

I 25 cm

3 0.1 mol dm

-3 hydrochloric acid

+ 5 g granule zinc .

II 25 cm

3 0.1 mol dm

-3 hydrochloric acid

+ 5g zinc powder

(a) State a hypothesis for this experiments. The smaller the size of zinc, the higher the rate of reaction between Zn and HCl.

Zinc

Hydrochloric

acid

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When iron nail coiled with less electropositive metal, iron nail rust.

-No rust Rusting

happens

very fast

-No rust -Rusting slowly

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When iron nail coiled with less electropositive metal is placed in potassium

hexacyanoferrate (III) and jelly solution, intensity of blue colour is high.

Metals provide sacrificial protection Metal that cannot provide sacrificial protection

-zinc, magnesium -copper

-Intensity of blue colour is higher than test tube B

(a) Problem statement

What is the effect of temperature on the rate of reaction between sodium thiosulphate

solution and hydrochloric acid?

(b) All the variables

MV: Temperature of sodium thiosulphate

RV: Rate of reaction/time taken for markX disappear.

FV: Concentration of sodium thiosulphate/HCl

(c) Hypothesis

-The higher the temperature of sodium thiosulphate, the shorter the time taken for

markX to disappear.

-Metals coiled with iron nail

-Rusting of iron

-Size of iron nail

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(d) List of materials and apparatus

- Filter paper, conical flask, thermometer, bunsen burner, tripod stand, wire

gauze,stopwatch, 25 cm3of 0.5 mol dm

-3 Na2S2O3, 10 cm

3 of 0.5 mol dm

-3 HCl

(e) Procedure

-Put conical flask on filter paper mark X

-Na2S2O3 is poured into conical flask

-Record the temperature of Na2S2O3

-Pour HCl into Na2S2O3 and start stopwatch

- Stop the stopwatch once mark X disappear and record time taken

-Step 1-5 is repeated bu heating Na2S2O3 at 40C,50C and 60C

(f) Tabulation of data

Temperature of Na2S2O3/C Time taken for markX disappear/s

40

50

60

(a) Problem statement

Which cleaning agent is effective,soap or detergent?

(b) All the variables

MV: Type of cleaning agent/Soap & detergent

RV: Presence of dirt/oily stain

FV: Volume of hard water

(c) Hypothesis

-Detergent will remove dirt from clothes in hard water but dirt remains when soap

used in hard water.

(d) List of materials and apparatus

-Hardwater, oily stain handkerchief, basin, soap, detergent

(e) Procedure

i) Pour hard water into 2 beakers

ii) Put 2 oily stain handkerchief into separate beakers

iii) Add soap and detergent into beakers and stir

iv) Scrub the handkerchief

v) Record the observation

(f) Tabulation of data

Type of cleaning agent Presence of oil stain

Soap

Detergent

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