a gas in cylinder expanded and dose 150 J of work pushing up the piston while 500 J of heat is supplied to it. what is the change in the internal energy of the gas in this process ?
A.150 J C.500 J
B.650 J D.350 J

Question

a gas in cylinder expanded and dose 150 J of work  pushing up the piston while 500 J of heat is supplied to it. what is the change in the internal energy of the gas in this process ?
A.150 J                       C.500 J
B.650 J                        D.350 J

anonymous · Answer

Use first law of thermodynamics in the following form$$\Delta Q = \Delta U +\Delta W$$
delta Q is amount of heat supplied/extracted
delta U is change in internal energy of system
delta W is the amount of work done by/on the system

The only thing to be careful here is the sign convention :-

delta Q is positive when heat is added to the system
delta U is positive if internal energy is increasing
delta W is positive if the system is doing work

In our case : delta Q =+500
                   delta W =+150