Calculate ΔE for a process in which a system performs 11.59 kJ of work and absorbs 4.41 kJ of heat. Express your answer to two places past the decimal in units of kJ

Answer 1

ΔE = q + w where q = heat and w = work. But the sign of these quantities depends on whether the system is losing (-q) or gaining heat (+q) and whether the system is doing the work (-w) or the surrounding is doing the work ON the system (+w).

In this problem, system performs work, so it is spending (-w) 11.59 kJ and it absorbs 4.41 kJ of heat (+q). Therefore,

ΔE =q + (-w) = 4.41 - 11.59 = -7.18 kJ