In: Chemistry
The gas in a piston (defined as the system) is warmed and absorbs 655 J of heat. The expansion performs 346 J of work on the surroundings. Part A What is the change in internal energy for the system? |
Ans. Change in internal energy, dU = q + w - equation 1
Where,
q = heat gained.
By convention, heat gained by system is denoted by “+ q” or positive value of q.
So, q = 655 J = + 655 J
w = work done by system.
By convention, work done by system is a “- w” or negative value of w.
So, w = - 346 J
Putting the values in equation 1-
dU = 655 J + (- 346 J) = 655 J – 346 J = + 309 J = 309 J
Hence, change in internal energy = 309 J
Note: The + sign of dU indicates that the system gained 309 J of energy during the change.