2013 BT1 H2 Chem P2 QP Edited

8/11/2019 2013 BT1 H2 Chem P2 QP Edited

http://slidepdf.com/reader/full/2013-bt1-h2-chem-p2-qp-edited 1/13

1

AJC BT1 2013 9647/02/H2 [Turn over

ANDERSON JUNIOR COLLEGE

Block Test 1 2013 (modified)

NAME: ______________________________ PDG: __________ Register No: _____

CHEMISTRY 9647/02Higher 2 8 January 2013

Paper 2 Structured Questions 1 hour 30 minutes

Candidates answer on the Question Paper.

Additional Materials: Data Booklet

This document consists of 13 printed pages.

Topics Tested:

Chemical Energetics

Chemical Equilibria

Ionic Equilibria

Chemical Periodicity

Reaction Kinetics

All Organic Chemistry until Arenes

IMPORTANT! Please read this first!

You need to revise on the topics first so that you can use thispaper to consolidate your learning and find out which are thetopics that you need to further work on.

Please attempt this paper as a time trial, noting the time given

(as indicated above) to complete it. Before you attempt the questions, check that you have the

following: Data Booklet Calculator



2


1 When fuel consisting of 2,3,4 –trimethylpentane, C8H18, is combusted in a car engine, it can form

either CO2 or CO, according to the following equations.

C8H18(l) +2

25O2(g) 8CO2(g) + 9H2O(l) --------------------------------------- (1)

C8H18(l) +2

17O2(g) 8CO(g) + 9H2O(l) --------------------------------------- (2)

The following data are available:

Reaction H o / kJ mol 1 S

o / J mol 1 K 1

(1) 5465 553

(2) 3261 +138

(a) (i) Calculate G

o

for reactions (1) and (2).

Go for reactions (1) ……………………………..

Go for reactions (2) ……………………………..

(ii) Hence, suggest, with reason, which reaction predominantly takes place during thecombustion of C8H18 under standard conditions.

……………………………………………………………………………………………………

……………………………………………………………………………………………………

(iii) On the axes provided below, sketch how G for each reaction (1) and (2) will varywith temperature. Label your sketches appropriately.

G / kJ mol1

0

T / K





4

AJC BT1 2013 9647/02/H2

2 (a) But –1 –ene and hydrogen chloride react together according to the equation:

CH2=CHCH2CH3(g) + HCl (g) CH3CHCl CH2CH3(g) ∆H < 0

To study the kinetics of this reaction, two students carried out their own different sets ofexperiments and obtained the following graphs.

(i) Use Student A's graph to deduce the order of reaction with respect to but –1 –ene.

……………………………………………………………………………………………………

……………………………………………………………………………………………………

(ii) Explain why the half –life of but –1 –ene in Student B's graph is not constant.

……………………………………………………………………………………………………

……………………………………………………………………………………………………

(iii) Given that the reaction is first order with respect to HCl , write the rate equation for thereaction, in terms of partial pressures.

……………………………………………………………………………………………………

(iv) Determine the value of the rate constant, k , for the reaction.

value of the rate constant, k …………………………….

(v) Deduce the half –life of but –1 –ene when the partial pressure of HCl is halved inStudent A’s experiment.

half –life of but –1 –ene ………………………. [5]

00

but –1 –enebut –1 –ene



5


(b) (i) Describe the mechanism for the reaction between but –1 –ene and HCl to produceCH3CHCl CH2CH3.

(ii) Sketch the energy profile diagram of the reaction between but –1 –ene and HCl . Label

clearly the activation energy and enthalpy change of the reaction.

(iii) Explain why the product formed in this reaction does not exhibit optical activity.

……………………………………………………………………………………………………

……………………………………………………………………………………………………

…………………………………………………………………………………………………… [6]



6

AJC BT1 2013 9647/02/H2

(c) Draw the structures of the organic products formed from the following reactions. Themolecular formula of the product formed in (c)(v) is given.

(i)

cold acidified KMnO4

(ii)

hot acidified KMnO4

(iii)

hot alkaline KMnO4

(iv)

CH3

conc HNO3, conc H2SO4

(v)

OHBr 2

C5H9OBr

[6][Total: 17]



7


3 (a) Many chemists have contributed to the development of the Periodic Table. John Newlandwas one of the first few chemists who attempted to classify elements in a systematic way,based on atomic weight. Part of Newland’s Periodic Table is shown below.

Row 1 5B 6C 7N 8O

Row 2 9F 11Na 12Mg 13 Al 14Si 15P 16S

Row 3 17Cl 19K 20Ca 24Cr 22Ti 25Mn 26Fe

On each of the grids below, sketch the general trends of the properties of the elementsacross Row 2 of Newland’s Periodic Table.

(i) (ii)

(iii) (iv)

[4](b) Aluminium oxide is amphoteric.

Write two equations that illustrate the amphoteric behavior of aluminium oxide and statewhich reaction is typical of a metal and which is typical of a non –metal.

Behaves like a

Equation 1: ……………………………………………… ……………………………………

Equation 2: ……………………………………………… …………………………………… [2]

Electrical conductivity of elements



8

AJC BT1 2013 9647/02/H2

(c) On crossing the second and third periods, the chlorides of the elements change in structureand in their reactions with water.

(i) 0.1 mol each of the four chlorides below is separately added to 1 dm of water.

Sketch a graph showing the variation in pH of these resulting solutions.

(ii) Account for the pH of the aqueous solutions of carbon tetrachloride and phosphoruspentachloride. Write balanced equations for the reactions, if applicable.

……………………………………………………………………………………………………..

……………………………………………………………………………………………………..

……………………………………………………………………………………………………..

…………………………………………………………………………………………………….. [4]

[Total: 10]

pH

7

NaCl Al Cl 3 CCl 4 PCl 5



9


4 In a typical laboratory, gas phase reactions are difficult to control and hence not common.Industrial production utilising gas phase reactions are similarly difficult to control and typically onlyused for manufacture of organic chemicals, sulfuric acid (Contact process) or ammonia (Haberprocess).

The Contact process used to produce sulfuric acid involves a three –stage process. Using V2O5

as a catalyst, reaction II achieves 99.5% conversion of sulfur dioxide to sulfur trioxide. Theessential reactions are as follows:

I: S(g) + O2(g) SO2(g) H = –308 kJ mol –1 II: 2SO2(g) + O2(g) 2SO3(g) H = –192 kJ mol –1 III: SO3(g) + H2O(l) H2SO4(l) H = –130 kJ mol –1

(a) Write an expression each for K c and K p of reaction II.

[2]



10

AJC BT1 2013 9647/02/H2

(b) The following graph shows how the concentration of SO3 varies with time in reaction II.

(i) A change in condition was introduced to the reaction mixture at t1 such that the

concentration of SO3 increases at a different rate after t1.

The dotted line in the graph above illustrates how the concentration of SO3 would varywith time if no change in condition was introduced at t1.

Suggest what this change could be and explain your answer.

……………………………………………………………………………………………….......

……………………………………………………………………………………………….......

……………………………………………………………………………………………….......

(ii) The equilibrium mixture at t2 was suddenly heated to a higher temperature.

Sketch on the graph above to show how the concentration of SO3 would change from t2 till equilibrium is reached.

(iii) Suggest and explain whether reaction II should be conducted at high or low pressure.

……………………………………………………………………………………………….......

……………………………………………………………………………………………….......

………………………………………………………………………………………………....... [4]

[Total: 6]

concentrationof SO3

timet1 t2 0



11


5 (a) Tartaric acid, C4H6O6, (can be represented as H2T) is a dibasic acid with the followingstructure.

HO

O

OH

O

OH

OH

At 298 K, K a1 and K a2 of tartaric acid are 1.05 x 10 –3 mol dm –3 and 4.57 x 10 –5 mol dm –3 respectively and it can ionise in stages.

H2T HT T2H+ H+

pK a1 pK a2

(i) Write an expression for K a1 of tartaric acid.

……………………………………………………………………………………………….......

(ii) Explain why K a2 is smaller than K a1.

……………………………………………………………………………………………….......

………………………………………………………………………………………………....... [2]

(b) 40 cm3 of a 0.30 mol dm –3 tartaric acid was titrated with a 0.6 mol dm –3 NaOH at 298 K.

(i) Calculate the volume of NaOH required for complete neutralisation of tartaric acid.Hence calculate the concentration of the salt solution formed.

volume of NaOH required ………………………

concentration of the salt solution formed ………………………



12

AJC BT1 2013 9647/02/H2

(ii) Write an equation to show why the pH at the second equivalence point of the titrationis greater than 7.

……………………………………………………………………………………………….......

(iii) Calculate the pH at the second equivalence point.

pH at the second equivalence point ………………………

(iv) Using the data given above and your answers to (b)(i) and (iii), sketch the pH –volumeadded curve of this titration.

[8]

(c) Potassium hydrogen tartrate, KHC4H4O6, (can be represented as KHT) is a potassium saltof tartaric acid, which occurs naturally in grapes.

K+O

-

O

OH

O

OH

OH

Unlike most potassium salt, potassium hydrogen tartrate has a relatively low solubility.



13


In an experiment conducted at 25 oC, solid potassium hydrogen tartrate is firstdissolved in pure water until no more solid dissolves. The excess solid is then filteredoff to give a saturated solution. The solubility of potassium hydrogen tartrate at 25 oCwas found to be 0.0328 mol dm –3.

(i) Write an expression for the solubility product of potassium hydrogen tartrate.

(ii) From the data given on page 16, calculate a value for K sp of potassium hydrogentartrate at 25 oC and state its units.

K sp of potassium hydrogen tartrate ……………………………...

(iii) The saturated solution is now heated to 30 oC in a water bath. Concentrated aqueousKNO3 is then added dropwise to the heated solution.

The value of the K sp of potassium hydrogen tartrate at 30 oC is 1.58 x 10 –3.

Determine the concentration, in mol dm –3, of K+ ions present when the first trace ofprecipitate appears. State any assumption you have made.

Assumption ……………………………………………………………………………………..

[4][Total: 14]

Documents

2013 BT1 H2 Chem P2 QP Edited