Question

When work done by a system was 10J. The increase in the internal energy of the system was 30J. The heat 'q' supplied to the system was:
1) -40J 2)+20J 3)+40J 4) -20J

Answer 1

I think +20J..........

Answer 2

chemistry /Thermodynamics

Given :-

1. work done, w = -10J
2. Internal energy = 30J

To find :-

The heat supplied to the system

Solution :-

using 1st law of Thermodynamics .i.e.,

"The net energy change in a closed system is equal to heat absorbed plus the work done by the system"

• ∆U = q + w

where,

∆U = change in Internal energy

q = heat gained or lost by the system

w = work done by the system

According to Question,

➠ ∆U = q + w

➠ 30 = q + (-10)

➠ q = 30 + 10

➠ q = +40J

thus, option (3) +40J is correct.

|| Note :- For absorption of heat 'q' is +ve and for release 'q' is -ve ||

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