A Levels

Only available on StudyMode
  • Download(s) : 176
  • Published : March 26, 2013
Open Document
Text Preview
w

w
ap
eP

m

e
tr
.X

w

*6364028069*

9701/05

CHEMISTRY
Paper 5 Planning, analysis and evaluation

October/November 2007
1 hour 15 minutes

Candidates answer on the Question Paper.
No Additional Materials are required.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen.
You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES.
Answer all questions.
You are advised to show all working in calculations.
Use of Data Booklet is unnecessary.
At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question.

For Examiner’s Use
1
2
Total

This document consists of 9 printed pages and 3 blank pages. SPA (NF/CGW) T30933/8
© UCLES 2007

[Turn over

om
.c

s
er

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS
General Certificate of Education Advanced Subsidiary Level and Advanced Level

2
1

The hydroxides of Group I metals (LiOH, NaOH, KOH, RbOH, CsOH) are highly corrosive white solids which rapidly absorb water vapour on exposure to the atmosphere. All of these solids dissolve exothermically in water.

The enthalpy change of solution, ΔHsoln, is the energy change associated with the following reaction. M represents the Group I metal.
M +(aq) + OH–(aq)

M OH(s) + (aq)

The following diagram represents theoretical stages in the formation of aqueous MOH. M +(g) + OH-(g) + (aq)

lattice energy

hydration enthalpy
of the ions
H hydration

M OH(s) + (aq)

H soln
M +(aq) + OH-(aq)
Lattice energy and hydration enthalpy are both more exothermic when ions carry a higher charge and/or ions have a smaller radius.
When comparing Group I hydroxides, changes in ΔHhydration are more significant than changes in lattice energy.
(a) By considering trends in the size and charge of the ions, predict the likely trend in ΔHsoln from LiOH to CsOH and sketch your prediction.
.......................................................................................................................................... .......................................................................................................................................... ..........................................................................................................................................

Hsoln

LiOH

NaOH

KOH

RbOH

CsOH
[2]

© UCLES 2007

9701/05/O/N/07

For
Examiner’s
Use

3
(b) The enthalpy change of solution, ΔHsoln, for any Group I hydroxide can be measured

For
Examiner’s
Use

experimentally in the laboratory.

In experiments to compare ΔHsoln for LiOH, NaOH, KOH, RbOH, CsOH state the independent variable .............................................................................. , the dependent variable ................................................................................................. , the other variable to be controlled .................................................................................. ........................................................................................................................................ . [3]

(c) Draw a labelled diagram to show the apparatus you would use to obtain data from which ΔHsoln could be determined.

From the information given on page 2 and the apparatus you plan to use, identify two possible sources of error in the experiment and state how you would minimise the effect of each.
error 1 ............................................................................................................................. .......................................................................................................................................... error 2...
tracking img