marking scheme paper 3

7/27/2019 Marking Scheme Paper 3

1/23

MARKING SCHEME PAPER 3

Question No. Rubric Score

1 (a) Able to state the inference correctly.

Sample answer:

The reactivity (of alkali metals with oxygen) increase fromlithium to potassium. //

Lithium so!ium an! potassium / alkali metals show similarchemical in their reactions with oxygen.

"

Able to state the inference less correctly.

Sample answer:

The reactivity increase //

#ll metals $urns pro!uce! white fume an! white soli! //

%oing !own group & the reactivity increase.

'

Able to state any idea of inference.

Sample answer:

Lithium so!ium an! potassium show !ifferent reactivity //

otassium So!ium lithium

&ncrease

1

No response or wrong response

1


2/23


1 ($) Able to state the three variables correctly:1. Method to manipulate variable.2. The responding variable.". The controlled variable.

Sample answer:

(i) *se !ifferent types of (alkali)/(group 1) metals

(ii) +eactivity of metals with oxygen //

,igorousness of the reaction $etween metals an!oxygen.

(iii) -xygen gas // sie / mass of metal

"

Able to state any two variables correctly:'

Able to state any one variable correctly.1


2


3/23


1 (c) Able to state the relationship correctly between themanipulated variable and the responding variable.

Sample answer:

(The lower/higher the position of metal in)/(%oing !own/up)%roup 1 the more/less reactive is the metal in reaction withoxygen. //

The lower/higher the position of metals in group 1 thelower/higher is the reactivity.

The metal which is lower / upper in %roup 1 is more/lessreactive in reaction with oxygen. //

The lower/higher the metal in %roup 1 the more/lessreactive the reaction with oxygen.

"

Able to state the relationship between the manipulatedvariable and the responding variable.

Sample answer:+eactivity increases for the reaction $etween alkali metalsan! oxygen when going !own %roup 1/ from lithium topotassium. //

(The lower/higher the position of metal in)/(%oing !own/up)%roup 1 the more/less reactive. //

The metal which is lower/upper in %roup 1 is more/lessreactive //

The lower/higher the metal in %roup 1 the more/lessreactive the reaction. //

The more reactive the reaction the lower the position of themetal in %roup 1.

'

Able to state the idea of hypothesis.

Sample #nswer:

etals in %roup 1 can react with oxygen. //

#lkali metals have !ifferent reactivity.

1


3


4/23


1 (!) Able to give the operational definition accurately by statingthe following three information.

- alkali metals- vigorously more vigorous reactive with o!ygen- more highly reactive

Sample answer:

#n alkali metal that reacts more vigorously with oxygen is amore reactive metal.

"

Able to give the operational definition correctly by statingany two of the information above.

Sample answer:

The metal that reacts more vigorously with oxygen is a morereactive metal. //

The alkali metal that reacts more vigorously is a morereactive metal. //

The higher/lower the alkali metals the more/less reactivemetal.

'

Able to give the operational definition correctly by stating

any one of the information above.

Sample answer:

#lkali metals can react with oxygen. //

etals can react vigorously with oxygen.

1


4


5/23


1 (e)(i) Able to state the position of metal " in #roup 1 accurately.

Sample answer:

erio! 0//2

"

Able to make a prediction of the position of metal " in #roup1 less accurately.

Sample answer:

3elow /un!er potassium //Lower than potassium

'

Able to make any prediction of the position of metal " in#roup 1.

Sample answer:

&n group 1 // *pper than Li/4a/5 // Lower than Li/ 4a

1


5


6/23


1 (e)(ii) Able to arrange the metals in ascending orderbased ontheir reactivity.

Sample answer:

Lithium So!ium otassium 6 // Li 4a 5 6

"

Able to arrange any three of the metals in ascending orderbased on their reactivity.

Sample answer:

6 Li 4a 5 // Li 5 4a 6 // 5 Li 4a 6 //4a Li 5 6 // 4a 5 Li 6 // Li 6 4a 5

'

Able to arrange any two of the metals in ascending order

based on their reactivity or arrange in descending order.

Sample answer:

6 5 Li 4a // 6 Li 4a 5 // 5 6 4a Li5 6 4a Li // 6 4a 5 Li // 4a 5 Li 6

6 5 4a Li //

1


6


7/23


1 (f) Able to state the relationship between the mass of sodiumand the time taken for the metal to burn completely ino!ygen gas.

- the higher the mass the bigger the si$e- the longer the time taken- burn completely

Sample answer:

The higher the mass of metals the longer the time taken to$urn completely. //

The $igger the sie of metals the longer the time taken to$urn completely.

"

Able to state the relationship between the mass of sodiumand the time taken for the metal to burn completely ino!ygen gas.

Sample answer:

The higher the mass of metals the longer the time taken. //

ore mass more time to $urn completely //

'

Able to state the relationship between the mass of sodiumand the time taken for the metal to burn completely in

o!ygen gas.

Sample answer:

3igger mass $urns longer. //

The metals nee!s longer time //

ore mass more time to $urn.

1


7


8/23


1 (g) Able to record all the readings with one decimal placeaccurately.

Sample answer:

1.1 1. 1.7

"

Able to record any two readings with one decimal placeaccurately.

Sample answer:

1.1 1. 1.8 // 1.1 1.0 1.7 // 1. 1. 1.7

'

Able to record at least one reading with one decimal placeaccurately.

Sample answer:

1.1 // 1. // 1.7

1


8


9/23


1 (h) Able to state observations for blue and red litmus papercorrectly.

Sample answer:

Solutions +e! litmus paper 3lue litmus paper

%as 9ar & Turns $lue 4o change

%as 9ar && Turns $lue 4o change

%as 9ar &&& Turns $lue 4o change

"

Able to state any one of the litmus paper observationscorrectly.

Sample answer:


%as 9ar & Turns $lue Turns re!%as 9ar && Turns $lue Turns re!

%as 9ar &&& Turns $lue Turns re!

//


%as 9ar & Turns re! 4o change

%as 9ar && Turns re! 4o change

%as 9ar &&& Turns re! 4o change

'

Able to give an idea on litmus paper observations.

Sample answer:


%as 9ar & 4o change Turns $lue

%as 9ar && 4o change Turns $lue

%as 9ar &&& 4o change Turns $lue

1


9


10/23


1 (i) Able to write the two balanced chemical e%uations for thereaction accurately.

Sample answer :

i. 4a ; -' '4a'- an!

ii. 4a'- ;


11/23


1 (=) Able to classify all alkaline solutions into strong alkali andone weak alkali correctly.

Sample answer:

Strong alkali : So!ium hy!roxi!e / 4a-eak alkali : #mmonia solution/ 4


12/23

@xperiment 1: 4a'S'-" ;


13/23


' (ii) Able to state the three variables correctly

Sample answer:

anipulate! varia$le:Temperature of so!ium thiosulphate solution+ate of reaction // Time taken for mark C6D to $ecomeinvisi$le /!isappear

?onstant varia$le:,olume an! concentration of so!ium thiosulphate/ sulphuricaci! / sie of conical flask

"

Able to state any two variables correctly '

Able to state any one variables correctly 1


13


14/23


' (iii) Able to state the relationship correctly between themanipulated variable and the responding variable withdirection.

Sample answer:The higher/lower the temperature of so!ium thiosulphatesolution the higher/lower the rate of reaction. //

The higher/lower the temperature of so!ium thiosulphatesolution the shorter/longer the time taken for mark C6D to!isappear from sight/view //

The increase/!ecrease in temperature of so!iumthiosulphate solution will increase/!ecrease the rate ofreaction. //

>hen the temperature of so!ium thiosulphate solutionincrease /!ecrease the rate of reaction willincrease/!ecrease.

"

Able to state the relationship between the manipulatedvariable and the responding variable with direction.

Sample answer:The higher/lower the temperature the higher/lower the rateof reaction. //

The higher/lower the temperature the shorter/longer thetime taken for mark C6D to !isappear //

The increases/!ecreases in temperature will increase/!ecrease the rate of reaction. //

'


Sample answerE

Aifferent temperature !ifferent reactivity. //

Temperature changes the time taken is !ifferent.

1


14


15/23


' (iv) #ble to give complete list of materials and apparatus

Sample answer:

aterials:So!ium thiosulphate solution sulphuric aci!.

#pparatus:?onical flask $unsen $urner measuring cylin!er (1 ml)measuring cylin!er (0 ml) stopFwatch filter /white/car!$oar! paper.

"

Able to give complete list of materials and four apparatus asfollowing.

#nswer:

aterials:So!ium thiosulphate solution sulphuric aci!.

#pparatus :?onical flask thermometer $unsen $urner filter / white/car!$oar! paper.

'

Able to give at least one substances and at least oneapparatus. 1


15


16/23


' (v) Able to list all the steps correctly

Sample #nswer:

1. C6 Cmark is !rawn on a piece of white/filter/ car!$oar!paper.

'. 0 cm"of so!ium thiosuphate solution G(.1F1.)mol !mF"H is measure! with a (0 cm") measuringcylin!er an! is poure! into a conical flask.

". The solution is slowly heate! until " o?.. 0 cm" of hy!rochloric aci! G(.1F '.) mol !mF"H is

measure! with a (1 cm")measuring cylin!er an! isa!!e! to the conical flask. # stopFwatch is starte!imme!iately.

0. The conical flask is swirle! an! is place! on awhite/filter/car!$oar! paper with a mark C6D.

. The C6D mark is o$serve! vertically from the top through the solution.2. The stopFwatch is stoppe! imme!iately when the C6D

mark cannot $e seen. Time is recor!e!.8. The experiment is repeate! $y using the so!ium

thiosuphate solution at o? 0 o? o? an! 2 o?respectively.

"

Able to list down steps 2' (' )' *' + '

#$le to give an i!ea to step . 1


16


17/23


' (vi) Able to tabulate the data with following aspects

1. ,orrect titles with units2. ,omplete list of temperatures

Sample answer:

Temperature(o?)

Time(s)

"

0

2

'

Able to contruct a table.

1. At least 1 titles correct without units2. -ncomplete list of tempereatures

Sample answer:

Temperature

" 1


17


18/23

@xperiment ': '


19/23


' (ii) Able to state the three variables correctly

Sample answer:

anipulate! varia$le:Temperature of hy!rochloric aci!

+espon!ing varia$le:+ate of reaction // ,olume of gas per unit time

?onstant varia$le:ass/sie of inc //,olume an! concentration of hy!rochloric aci!

"

Able to state any two variables correctly '

Able to state any one variables correctly 1


19


20/23


' (iii) Able to state the relationship correctly between themanipulated variable and the responding variable withdirection.

Sample answer:The higher/lower the temperature of hy!rochloric aci! thehigher/lower the rate of reaction. //

The higher/lower the temperature of hy!rochloric aci! thehigher/lower the volume of the hy!rogen gas release perunit time //

The increase/!ecrease in temperature of hy!rochloric aci!will increase/!ecrease the rate of reaction. //

>hen the temperature of hy!rochloric aci!increases/!ecreases the rate of reaction willincrease/!ecrease.

"

Able to state the relationship between the manipulatedvariable and the responding variable with direction.

Sample answer:The higher/lower the temperature the higher/lower the rateof reaction. //

The higher/lower the temperature the higher/lower thevolume of the hy!rogen gas release! per unit time. //

The increase/!ecrease in temperature willincrease/!ecrease the rate of reactions. //

'


Sample answerE

Aifferent temperature !ifferent reactivity. //

Temperature changes the time taken is !ifferent.

1


20


21/23


' (iv) #ble to give complete list of materials and apparatus

Sample answer:

aterials:Iinc hy!rochloric aci!

#pparatus:?onical flask thermometer $unsen $urner stopFwatchmeasuring cylin!er (0 ml) !elivery tu$e an! stopper$urette $asin

"

Able to give all materials and five apparatus as following.

#nswer:

aterials:Iinc hy!rochloric aci!

#pparatus :?onical flask thermometer $unsen $urner !elivery tu$e$urette

'

Able to give at least one substance and at least oneapparatus. 1


21


22/23


' (v) Able to list all the steps correctly

Sample #nswer:

1. 3urette is fille! with water an! inverte! into a $asincontaining water.

'. The $urette is clampe! vertically using retort stan!.". &nitial rea!ing of $urette is recor!e!.. G'F0H cm"of hy!rochloric aci! G(.1F1.) mol

!mF"H is measure! with a (0 ml) measuring cylin!eran! is poure! into a conical flask.

0. The solution is slowly heate! until " o?.. ' g of inc is weighe! an! is put into the conical

flask.2. The conical flask is close! imme!iately with a

stopper which is =oine! to the !elivery tu$e an!the stopwatch is starte!.

8. The $urette rea!ing is recor!e! at interval of "secon!s until the reaction is complete!.

7. The experiment is repeate! $y using thehy!rochloric aci! at o? 0 o? o? an!2 o? respectively.

"

Able to list down steps 1' (' ' +' / '

#$le to give an i!ea to step . 1


22


23/23


' (vi) Able to tabulate the data with following aspects

1. ,orrect titles with units2. ,omplete list of temperatures

Sample answer:

Temperature(o?)

Time(s)

"

0

2

'

Able to contruct a table.

1. At least 1 titles correct without units2. -ncomplete list of tempereatures

Sample answer:

Temperature

"1


END OF MARKING SCHEME

marking scheme paper 3

Documents