Question

If 1 mol of an ideal gas at constant temperature
changes its pressure from 5 atm to 2 atm and
volume from 4 L to 10 L, then enthalpy change will
be
[refer NCERT Pg. 167]
(1) 20 L-atm
(2) 120 L-atm
(4) 100 L-atm
(3) Zero
pls give the explanation.....

Answer 1

Answer:

he answer is zero

Let ...P1 =5 atm   P2=2 atm

       V1=4L       V2=10L

now, at constant temperature(isothermal)  q = -w... so U=0

H1=U + P1V1                        

H1= 20 L-atm

similarly, H2= 20 L-atm

change in enthalpy..

delta H= H2-H1

delta H= 20-20 = 0