Question

Suppose a system receives a ""deposit"" of 50 J of work from the surroundings and loses a ""withdrawal"" of 84 J of heat to the surroundings. What is the magnitude and the sign of ΔE for this process? Express your answer using two significant figures

Answer 1

Answer : The value of $\Delta E$ for this process is, -34 J

Explanation :

First law of thermodynamic : It states that the energy can not be created or destroyed, it can only change or transfer from one state to another state.

As per first law of thermodynamic,

$\Delta E=q+w$

where,

$\Delta E$ = internal energy of the system  = ?

q = heat rejected to the surrounding  = -84 J

w = work done  = +50 J

Now put all the given values in the above expression, we get:

$\Delta E=(-84J)+(+50J)$

$\Delta E=-34J$

Therefore, the value of $\Delta E$ for this process is, -34 J