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Date November 2017 Marks available 3 Reference code 17N.3.SL.TZ0.1
Level Standard level Paper Paper 3 Time zone Time zone 0
Command term Determine Question number 1 Adapted from N/A

Question

In an experiment, data were collected on the variation of specific heat capacity of water with temperature. The graph of the plotted data is shown.

The uncertainty in the values for specific heat capacity is 5%.

Water of mass (100 ± 2) g is heated from (75.0 ± 0.5) °C to (85.0 ± 0.5) °C.

Draw the line of best-fit for the data.

[1]
a.

Determine the gradient of the line at a temperature of 80 °C.

[3]
b.i.

State the unit for the quantity represented by the gradient in your answer to (b)(i).

[1]
b.ii.

Calculate the energy required to raise the temperature of the water from 75 °C to 85 °C.

[1]
c.i.

Using an appropriate error calculation, justify the number of significant figures that should be used for your answer to (c)(i).

[3]
c.ii.

Markscheme

single smooth curve passing through all data points

 

Do not accept straight lines joining the dots

Curve must touch some part of every x

a.

tangent drawn at 80 °C

gradient values separated by minimum of 20 °C

9.0 × 10–4 «kJ kg–1 K–2»

Do not accept tangent unless “ruler” straight.

Tangent line must be touching the curve drawn for MP1 to be awarded.

Accept values between 7.0 × 10–4 and 10 × 10–4.

Accept working in J, giving 0.7 to 1.0

b.i.

kJ kg−1 K−2

 

Accept J instead of kJ

Accept °C–2 instead of K−2

Accept °C–1 K–1 instead of K−2

Accept C for °C

b.ii.

«0.1 x 4.198 x 10 =» 4.198 «kJ» or 4198 «J»

Accept values between 4.19 and 4.21

c.i.

percentage uncertainty in ΔT = 10%

«2% + 5% + 10%» = 17%

absolute uncertainty «0.17 × 4.198 =» 0.7 «kJ» therefore 2 sig figs

OR

absolute uncertainty to more than 1 sig fig and consistent final answer

Allow fractional uncertainties in MP1 and MP2

Watch for ECF from (c)(i)

Watch for ECF from MP1

Watch for ECF from MP2

Do not accept an answer without justification

c.ii.

Examiners report

[N/A]
a.
[N/A]
b.i.
[N/A]
b.ii.
[N/A]
c.i.
[N/A]
c.ii.

Syllabus sections

Core » Topic 3: Thermal physics » 3.1 – Thermal concepts
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