Answer to Question #337580 in General Chemistry for George

Question

An object doing work at 541 J while losing 134 J of heat, calculate the value of E.

Answer 1

By the first law of thermodynamics,  the conservation of energy states that the total energy of an isolated system is constant. So here to determine the E we need to count the energy that was lost and gained by the system:

$\Delta U = Q-W$, where Q is the heat added and W is the work done by the system. Since the system lost the heat, the sign will be negative:

$\Delta U = -134J -541J = -675J$