Question

When 1 mol gas is heated at constant volume temp. is raised from 298 to 308 K. Heat supplied to the gas is 500 J. Then which statement is correct?

• A. q = w = 500 J, U = 0
• B. q = U = 500J, w = 0
• C. q = w = 600 J, U = 0
• D. U = 0, q = w = 400 J

Answer 1

The correct option is B q = U = 500J, w = 0

According to First Law of Thermodynamics, q = U + w

Here 'q' is heat supplied , 'U' is change in internal energy ,'w' is amount of work done.

As w = -PdV here volume is constant so dV = 0 that says w = 0.

heat supplied (q) = 500J (given)

By First Law of Thermodynamics ,

q= U +w

q = U (since w = 0)

q = U = 500J