Question

Calculate the change in internal energy of a system which absorb 100 J heat and does 215 J of work.​

Answer 1

Answer:

From first law of thermodynamics,

ΔH=ΔE+W

ΔE=ΔH−W

Given that:-

W=+20J(Work done on the system is positive)

ΔH=100J

∴ΔE=100−20=+80J

Hence the correct answer is +80J.

Answer 2

Answer:

The change in internal energy is -115J.

Explanation:

Internal energy is the sum of the potential energy of the system and the kinetic energy of the system.

From the first law of thermodynamics,

ΔQ=ΔE+W

Where Q= heat absorbed or released; E = internal energy of the system; W= work done by system or system

Also ΔE=ΔQ-W

Whereas the:-

W=+215 J (Work done on the system is positive)

ΔQ=+100J (since absorbed heat is positive)

Therefore ΔE=ΔQ−W

∴ΔE=100−215= - 115J

The change in internal energy is therefore -115J.

#SPJ3