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Question 19M.3.SL.TZ2.10c

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Date May 2019 Marks available [Maximum mark: 3] Reference code 19M.3.SL.TZ2.10c
Level SL Paper 3 Time zone TZ2
Command term Determine Question number c Adapted from N/A
c.
[Maximum mark: 3]
19M.3.SL.TZ2.10c

A heat pump is modelled by the cycle A→B→C→A.

The heat pump transfers thermal energy to the interior of a building during processes C→A and A→B and absorbs thermal energy from the environment during process B→C. The working substance is an ideal gas.

(c)

Determine, using the first law of thermodynamics, the total thermal energy transferred to the building during the processes C→A and A→B.

[3]

Markscheme

for CA ΔU = 0 so Q = W = −440 «J» ✔

for AB W = 0 so Q = ΔU = −375 «J» ✔

815 «J» transferred to the building ✔

Must use the first law of thermodynamics for MP1 and MP2.

Examiners report

The main problem here was deciding whether each Q was positive or negative. But the question was quite well answered.

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