a. Calculate EΔ for a system that gains 34.5 kJ of heat and performs 25.8 kJ of work on its surroundings.

1. a. Calculate EΔ for a system that gains 34.5 kJ of heat and performs 25.8 kJ of work on its surroundings. 

ΔE= H+ W

heat = +34.5 kJ ---- gaining heat 

work =-25.8kJ----- work done by the system), 

thus 

E=+34.5kj + (-25.8kJ)=8.7kJ

b. Calculate ΔE for a system that gains 69.8 kJ of heat and has 15.6 kJ of work done to it by the surroundings. 

ΔE= H+ W

heat = +69.8 kJ ---- gaining heat 

work =+15.6kJ------done on the system

ΔE=+69.8kJ + 15.6kJ=85.4kJ

c. Calculate ΔE for a system that lose 25.6 kJ of heat and does 15.6 kJ of work on its surroundings. 

ΔE= H+ W

heat = -25.6 kJ ---- loses heat 

work =-15.6kJ------ W done by the system), 

ΔE=-25.6kJ -15.6kJ=-41.6kJ

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