1/31 Heat Work Enthalpy Adiabatic examples

Question 1

if a gas is being compressed at a constant temperature, what are the values for q, w, ∆H, and ∆U

Answer 1

work must be positive since we are compressing the gas

∆U and ∆H must be equal to zero since ∆T is zero

since ∆U=0, then 0=q+w and q=-w so q must be negative because w is positve

Question 2

what does adiabatic mean

Answer 2

it relates to processes that occur with no heat transfer (q=0)

Question 3

for adiabatic expansion, what is the sign of work

Answer 3

work is negative

Question 4

for adiabatic expansion, what is the sign of ∆H, ∆U, and ∆T

Answer 4

∆H and ∆U are negative and ∆T is also negative

Question 5

why is ∆T negative in adiabatic expansion

Answer 5

when we work on the surroundings without any heat input into the system, we lose energy. If we are losing energy then the temperature is decreasing