Question

A system releases 255 cal of heat to the surroundings while delivering 428 cal of work. what is the change in internal energy of the system (in cal)?

Answer 1

Answer:-683 cal

Explanation:

Given

Heat released by system Q=-255 cal

as heat released is taken as negative and vice-versa

Work done by system W=428 cal

From First law of thermodynamics

$Q=\Delta +W , where \Delta U$=change in internal Energy

$\Delta U=-255-428=-683$

Answer 2

The change in the internal energy of the system is 173 cal.

First Law of thermodynamics:

It is given that the heat energy released by the system is ΔQ = -255 cal, and the work delivered is ΔW=-428 cal. The negative sign indicates that the heat energy of the system is decreasing as it is released to the surrounding. The negative sign in the work done indicates that the work is done by the system on the surrounding.

So from the first law of thermodynamics:

ΔQ = ΔU + ΔW

-255cal  = ΔU - 428 cal

ΔU = 173 cal is the change in internal energy of the system.

Learn more about the laws of thermodynamics:

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