Question

A sample of gas absorbs 4000 kJ of heat. (a) If volume remains constant, what is AU? (b) Suppose that in addition to the absorption of heat by the sample, the surroundings do 2000 kJ of work on the sample, what is AU? (c) Suppose that as the original sample absorbs heat, it expands against atmospheric pressure and does 600 kJ of work on its surroundings. What is A U? [(a) 4000 kJ (b) 6000 kJ (c) 3400 kJ]

Answer 1

G⃗I⃗V⃗E⃗N⃗: Q⃗=+4⃗0⃗0⃗0⃗ K⃗J⃗(H⃗E⃗A⃗T⃗ A⃗B⃗S⃗O⃗R⃗B⃗E⃗D⃗)

ΔV⃗=0⃗ (V⃗O⃗L⃗U⃗M⃗E⃗ C⃗O⃗N⃗S⃗T⃗A⃗N⃗T⃗)

Q⃗=ΔV⃗=4⃗0⃗0⃗0⃗ K⃗J⃗

(I⃗I⃗) Q⃗=+4⃗0⃗0⃗0⃗ K⃗J⃗W⃗=+2⃗0⃗0⃗0⃗ K⃗J⃗ (W⃗O⃗R⃗K⃗ D⃗O⃗N⃗E⃗ B⃗Y⃗ S⃗U⃗R⃗R⃗O⃗U⃗N⃗D⃗I⃗N⃗G⃗)

ΔU⃗=Q⃗+W⃗

ΔU⃗=4⃗0⃗0⃗0⃗+2⃗0⃗0⃗0⃗=6⃗0⃗0⃗0⃗ K⃗J⃗

(I⃗I⃗I⃗) Q⃗=+4⃗0⃗0⃗0⃗ K⃗J⃗W⃗=−6⃗0⃗0⃗ K⃗J⃗ (W⃗O⃗R⃗K⃗ D⃗O⃗N⃗E⃗ O⃗N⃗ T⃗H⃗E⃗ S⃗U⃗R⃗R⃗O⃗U⃗N⃗D⃗I⃗N⃗G⃗)

ΔU⃗=Q⃗+W⃗

ΔU⃗=4⃗0⃗0⃗0⃗−6⃗0⃗0⃗=3⃗4⃗0⃗0⃗ K⃗J⃗