A 150 W electric heater operates for 12.0 min to heat an ideal gas in a cylinder. During this time, the gas expands from 3.00 L to 11.0 L against a constant pressure of 1.03 atm. What is the change in internal energy (in kJ) of the gas?

The change in internal energy of the gas is 108.835 kJ

Explanation:

To calculate the work done for reversible expansion process, we use the equation:

where,

W = work done

P = pressure = 1.03 atm

= initial volume = 3.00 L

= final volume = 11.0 L

Putting values in above equation, we get:

    (Conversion factor:  1 L. atm = 101.325 J)

Calculating the heat from power:

where,

Q = heat required

P = power = 150 W

t =  time = 12 min = 720 s       (Conversion factor:  1 min = 60 s)

Putting values in above equation:

The equation for first law of thermodynamics follows:

where,

Q = total amount of heat required = 108 kJ

dU = Change in internal energy = ?

W = work done  = -0.835 kJ

Putting values in above equation, we get:

Hence, the change in internal energy of the gas is 108.835 kJ

the answers would be

the first one and the second one