Paper 2 Grade 11 - 2011

8/11/2019 Paper 2 Grade 11 - 2011

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Vere Technical High School

Mid of Year Examination

ChemistryPaper 2

2 hour 3 minutes

!e"ruary 2##

SECTION A

Answer all questions

Do no spent more than 30 minutes on question 1

Volumetric Analysis - Titration

#$ (a) % student is as&ed to ma&e a solution of sodium hydroxide "y dissol'ing an

un&no(n mass of the pellets in 2)cm3 of (ater$ 2)$ cm3 of the solution is then titrated

against a standard solution of hydrochloric acid *$) mol dm +3,$

!igure # "elo( sho(s the initial and final 'olumes of the "urette reading for the 'olumeof acid added$

%'erage 'olume of acid used - cm3

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(4 marks

*ii, /rite a chemical e0uation for the reaction that occurs during the titration$

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(1 marks

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!rom the data in Ta"le # calculate E%CH of the follo(ing1

*iii, The num"er of moles of hydrochloric acid in the titration ..............................................................................

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(1 mark

*i', The num"er of moles of sodium hydroxide in 2)$ cm3 of the solution

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(1 mark

*', The num"er of moles of sodium hydroxide in 2) cm3 of solution

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(1 mark

(i Mass of sodium hydroxide dissol'ed in 2) cm3 of (ater

*elati'e atomic mass1 a 4 235 6 4 #75 H 4 #,

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(! marks

(Total 10 "arks

*", Vinegar is (idely used to add fla'or to salads and other foods$ There are many "rands of

'inegar a'aila"le on the mar&et$ They all contain ethanoic acid *acetic acid, as the acti'e

ingredient$ !igure 3 sho(s the la"els of three "rands of 'inegar that can "e found in asupermar&et shelf$ They all claim the content contain )8 ethanoic acid5 (hich essentially

is ) gdm+3 of ethanoic acid$

Plan and design an experiment to determine (hether the three "rands of 'inegar do in

fact contain the same concentration of ethanoic acid$

Your ans(er should include the follo(ing

*i, Hypothesis to "e tested

8/11/2019 Paper 2 Grade 11 - 2011


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*ii, %pparatus and materials

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*iii, Method

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*i', Varia"les

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*', 9ata to "e collected

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*'i, Predicted esults

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8/11/2019 Paper 2 Grade 11 - 2011


*'ii, Possi"le Sources of error

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10 marks

*c, The information pro'ided in Ta"le : "elo( refers to atoms of t(o elements5 % and

;$

*i, Complete Ta"le : "y (riting the re0uired information in the rele'ant spaces

TA$%E 4& ATO"IC 'O'ETIES O) E%E"ENTS A AND $

P6PET<ES A ;

Mass num"er #=

%tomic num"er #2

um"er of protons =

um"er of electrons #2 =

um"er of neutrons #2

Electronic configuration

>roup num"er 2

Period num"er 2

(4 marks

(ii /hat type of "ond (ould ta&e place "et(een % and ;?

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(1 mark

(iii >i'e a reason for your ans(er in *ii, a"o'e$

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(! marks

(i* @se dot cross diagrams to illustrate the "onding "et(een % and ;$

8/11/2019 Paper 2 Grade 11 - 2011


(! marks

(* 9escri"e the "onding expected in %$

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(! marks

(*i 9escri"e the "onding in graphite$

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(! marks

(*ii >raphite is used as a lu"ricant$ Ho( does this use relate to its structure and

"onding?

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(! marks

Total 1+ marks

2$ *a, Transition "et(een the three states of matter can "e efficiently illustrated "y using

(ater$

Consider the information gi'en in !igure 3 and ans(er the 0uestions that follo($

*i, ame the THEE states of matter

8/11/2019 Paper 2 Grade 11 - 2011


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(1 mark

*ii, /hich of the t(o temperatures5 *%, and *;, in !igure 3 represents

Melting point? .....................................................

;oiling point? .....................................................

(! marks

*iii, /hat (ould "e o"ser'ed at *C, in !igure 3?

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(1 mark

*i', ame the process (hich occurs (hen the follo(ing con'ersions ta&e place$

/ater 'apour (ater .............................................

<odine*s, <odine *g, ............................................

(! marks

*", 9iamond and graphite are "oth allotropes of car"on$

*i, Explain (hat is meant "y the term AallotropeB$

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(1 mark

(*iii /hich of the t(o allotropes of car"on5 diamond or graphite5 conducts electricity?

Explain your ans(er in terms of the structure and "onding of the t(o allotropes$

Conducts electricity1.................................................

Explanation1.......................................................

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(! marks

(Total , marks

8/11/2019 Paper 2 Grade 11 - 2011


3$ Ta"le # presents some information on the reactions of compound % and copper metal (ith

'arious reagents$ @se the information in Ta"le # to ans(er the 0uestions that follo($

TA$%E 1& SO"E EACTIONS O) CO"'O-ND A AND CO''E

ea.tions with

%cidified potassium

chromate *'i,

solution

%0ueous iron *<<,

nitrate

%0ueous sil'er

nitrate solution

%0ueous Solution of

%

Experiments #

Potassium chromate

*'i, changes from

orange to green

Experiment 2

The iron *<<, nitrate

changes from pale

green to pale yello($

Copper metal Experiment 3 Experiment :

Sil'er solid is

deposited$ Pale "lue

solution is formed$

*a, *i, Classify solution % as an oxidiing or reducing or a reducing agent in Experiment #

and 2$Experiment #1 A is acting as DDDDDDD

Experiment 21 A is acting as DDDDDDD

(! marks

*ii, @sing the information gi'en in Ta"le # only5 explain your ans(er to *a, *i, a"o'e

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(4 marks

*", *i, /rite a "alanced ionic e0uation to represent the reaction that occur in Experiment :$

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(! marks

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*ii, %ccount for the pale "lue solution that is o"ser'ed in Experiment :$

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(1 mark

*c, /ith reference to the electrochemical series5 predict (hat you may "e expected to

o"ser'e in experiment 3$ >i'e reason for your ans(er$

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(3 marks*d, /hen exposed to air for some time5 copper ornaments "ecomes tarnished "y green

copper car"onate$

*i, Suggest the name of a common household chemical that can "e used to clean such

tarnished copper ornaments$

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(1 mark

*ii, /rite a suita"le ionic e0uation to sho( the reaction in *d, *i, a"o'e$

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(! marks

(Total 1+ marks

8/11/2019 Paper 2 Grade 11 - 2011


SECTION $

Answer A%% questions in this se.tion

1/ Car"on can exist in t(o allotropic forms5 diamond and graphite$ S&etch diagrams to sho(

the structures of diamond and graphite ( marks

*ii, <t sis o"ser'ed that if the AleadB *graphite, in a pencil is ru""ed on a &ey that is

stic&ing in a loc&5 the &ey usually turns freely$ Explain this o"ser'ation in terms of the

structure of graphite (3 marks

*", %lthough there are more than one thousand isotopes5 only a"out one hundred and nine

elements exist$ >i'e 6E reason for this o"ser'ation (! marks

*ii, aturally occurring sil'er is a mixture of t(o isotopes5 :%g and :%g$ Ho(e'er5 its

relati'e atomic mass is #F$ <n contrast5 although naturally occurring car"on is a mixture

of t(o isotopes5 7C and 7C5 its relati'e atomic mass is #2$ Explain ho( this is possi"le$

(! marks

(i State T/6 uses of the 7C isotope$ (! marks

Total 1+ marks

!/ The element chromium *Cr, forms a num"er of compounds in (hich chromium exhi"its

different oxidation num"ers$ Chromium5 unli&e iron5 is also highly resistant to corrosion

and5 as such5 it is (idely used to chrome+plate o"Gects$

*a, *i, Potassium dichromate * 2Cr 26, is a common reagent in a schoolBs la"oratory$

9escri"e 6E use of potassium dichromate as a la"oratory reagent$

Your ans(er should indicate the test it is used for5 the method of carrying out the

test and any colour changes expected$ (4 marks

(ii Calculate the oxidation num"er of chromium in potassium dichromate

* 2Cr 26, and in chromium sulphate *Cr 2*S6:,3, (! marks

(iii ;ased on your ans(er in *ii, a"o'e5 deduce the type of reaction (hich

occurs (hen 2Cr 26 is con'erted to Cr 2*S6:,3$ (1 marks

*", Electrolysis is a chemical process$ <t is used to extract highly reacti'e su"stances

such as sodium and chlorine from their compounds$

a/ 9efine the term AelectrolysisB$ (! marks

*ii, @sing molten sodium chloride as an example of an electrolyte1

*a, 9escri"e (hat happens during the process of electrolysis

107 109

12 14

14

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*", Sho( (hy electrolysis is a chemical process$ Support your ans(er (ith rele'ant ionic

e0uations ( marks

(Total 1+ marks

SECTION C

3/The increase in the intensity and fre0uency of hurricanes and flooding in the Cari""ean has

"een attri"uted in some 0uarters to an increase in the a'erage glo"al temperature$ The rise

in glo"al temperature has "een partially attri"uted to the increase in green house gases in

the atmosphere$

a/ ;riefly outline ho( green houses gases can contri"ute to an increase of the earths

atmospheric temperature$

<nclude in your ans(er1

i/ The name of the main green house gas (1 mark

ii/ T(o main causes of the increase in concentration of the named green

house gas$ (! marks

iii/ %n explanation of ho( E%CH of the causes named in *ii, a"o'e can lead

to the increase of this gas in the atmosphere$ (3 marks

You should include 6E chemical e0uation in your ans(er

i*/ % "rief explanation of ho( the green house effect (or&s$ @se a la"eled

diagram to illustrate your ans(er$ (+ marks

2/ There is a claim that the use of electrical cars can completely eliminate the

greenhouse gases$ 9o you support this statement? Suggest T/6 reasons for your

ans(er$ (! marks

./ 6'er the years5 studies ha'e sho(n that there has "een a significant decrease in

the le'els of the oone layer$ This has "een lin&ed to the extensi'e use of

chloroflurocar"ons *C!Cs, for many years$

9iscuss the significance of the a"o'e statement ma&ing reference to1

• The function of the oone layer

• The action of C!Cs on the oone layer

• T(o health or en'ironmental effects of the reduction of the oone layer

• T(o possi"le long term implication for the Cari""eanBs tourism industry

• 6E measure that has "een put in place to reduce the amount of C!Cs in

the atmosphere$ ( marks

Total !0 marks

END O) E5A"

Paper 2 Grade 11 - 2011

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