Chemistry Paper 2

Topics: Thermodynamics, Sodium hydroxide, Oxidation state Pages: 24 (1784 words) Published: January 25, 2014
N10/4/CHEMI/SP2/ENG/TZ0/XX

88106105

CHEMISTRY
STANDARD LEVEL
PAPER 2
Thursday 11 November 2010 (afternoon)

Candidate session number
0

1 hour 15 minutes

0

INSTRUCTIONS TO CANDIDATES





Write your session number in the boxes above.
Do not open this examination paper until instructed to do so. Section A: answer all of Section A in the spaces provided.
Section B:
answer one question from Section B. Write your answers on answer sheets. Write your session number on each answer sheet, and attach them to this examination paper and your cover sheet using the tag provided. • At the end of the examination, indicate the numbers of the questions answered in the candidate box on your cover sheet and indicate the number of sheets used in the appropriate box on your cover sheet.

8810-6105

13 pages
© International Baccalaureate Organization 2010

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N10/4/CHEMI/SP2/ENG/TZ0/XX

SECTION A
Answer all the questions in the spaces provided.
1.

The data below are from an experiment to measure the enthalpy change for the reaction of aqueous copper(II) sulfate, CuSO4 (aq) and zinc, Zn (s). Cu 2+(aq ) + Zn (s) → Cu (s) + Zn 2+(aq )

50.0 cm3 of 1.00 mol dm–3 copper(II) sulfate solution was placed in a polystyrene cup and zinc powder was added after 100 seconds. The temperature-time data was taken from a data-logging software program. The table shows the initial 23 readings.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

B

C

time / s
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0
13.0
14.0
15.0
16.0
17.0
18.0

Temperature / °C
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8
24.8

Temperature / °C

A

D

E

F

G

H

80

60

40

20

Linear fit for selected data.
T = – 0.050t + 78.0
T Temperature
t time
0

100

200

300

400

time / s

A straight line has been drawn through some of the data points. The equation for this line is given by the data logging software as
T = − 0.050 t + 78.0

where T is the Temperature at time t.
(This question continues on the following page)
8810-6105

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N10/4/CHEMI/SP2/ENG/TZ0/XX

(Question 1 continued)
(a)

The heat produced by the reaction can be calculated from the temperature change, DT , using the expression below.
Heat change = Volume of CuSO4 (aq) ´ Specific heat capacity of H 2 O ×∆T [2]

Describe two assumptions made in using this expression to calculate heat changes.

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (b) (i)

Use the data presented by the data logging software to deduce the temperature change, DT , which would have occurred if the reaction had taken place instantaneously with no heat loss.
[2]

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(ii) State the assumption made in part (b) (i).

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