Calculate ∆E for the following case:

q = + 1.62 kJ and w = - 874 J

a. - 872 J

b. - 746 J

c. + 746 J

d. + 872 J

e. + 2.49 kJ

The internal energy (ΔE) of a substance is calculated below:

From the first law of thermodynamics;

ΔE=q+w

Explanation:

ΔE=q+w

here;

+q=endothermic reaction

-q=exothermic reaction

+w=work done on the system

-w=work done by the system

Given:

q=+1.62kJ=1620J

w=-874J

To solve:

the internal energy (ΔE)

We know:

ΔE=q+w

according to the problem;

ΔE=q-w

since;

w=-874J (i. e.) work is done by the system.

ΔE=1620-874

ΔE=+746J

Therefore the internal energy is + 746J

i. e. the option is "c" (+746J)