Answer:
- 247 kJ
Explanation:
The formula you need to now is very simple:
ΔE = Q + W
This basically means that in order to calculate ΔE, you need to now the heat Q that the system loses or gains, and the work W that it perfoms or receives.
The system that we have loses heat, so Q is negative, and performs a work, which consumes energy, therefore W is also negative. So, in conclusion, we have:
ΔE = Q + W = -79 kJ - 168kJ = - 247 kJ.
The system loses 247 kJ of energy.
The change in the internal energy of the system is 247 kJ while the negative sign denotes that the energy is been lost by the system.
We know that according to the first law of thermodynamics energy can not be created nor be destroyed. therefore,
[tex]\triangle E = Q - W[/tex]
where Q is the heat given to the system, and W is the work done by the System of its surrounding,
GIven to us
Work done by the system on the surrounding, W = 168 kJ
Heat lost by the system, Q = -79 kJ
Substitute the values,
[tex]\rm \triangle E = -79 - 168 = -247\ kJ[/tex]
Hence, the change in the internal energy of the system is 247 kJ while the negative sign denotes that the energy is been lost by the system.
Learn more about First law of thermodynamics:
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