Question

Calculate the change in internal energy (ΔE) for a system that is giving off 25.0 kJ of heat and is changing from 12.00 L to 6.00 L in volume at 1.50 atm pressure. (Remember that 101.3 J = 1 L∙atm)

Answer 1

Explanation:

The given data is as follows.

         q = -25.0 kJ,     Pressure (P) = 1.50 atm

   $\Delta V$ = (12 - 6) L = 6 L

Therefore, product of pressure and change in volume will be as follows.

             $P \Delta V = 1.50 atm \times 6 L$

                                = 7.5 L atm

                                = $7.5 \times 101.3$

                                = 759.75 J

Now, we will calculate the change in internal energy as follows.

                   $\Delta E = q + w$

                                = $q + P \Delta V$

                                = -25000 kJ + 759.75 J

                                 = 24240.25 J

or,                              = 24.240 kJ      (as 1 kJ = 1000 J)

Thus, we can conclude that the change in internal energy ($\Delta E$) for a system is 24.240 kJ.