70j of energy are given off by a volume of gas to an outside system. Then the gas expands and does 45j of work outside the system. What is the net internal change the internal energy of this volume of gas?
The net internal change in the internal energy of the gas can be calculated using the first law of thermodynamics, which states that the change in internal energy (ΔU) is equal to the heat added to the system (Q) minus the work done by the system (W):
ΔU = Q - W
In this case, Q is the heat given off by the gas to the outside system, which is 70J, and W is the work done by the gas outside the system, which is -45J (since the gas does work on the outside system).
Plugging the values into the equation:
ΔU = 70J - (-45J)
= 70J + 45J
= 115J
Therefore, the net internal change in the internal energy of this volume of gas is 115J.
Formula for net internal energy
The formula for the net change in internal energy (ΔU) of a system can be calculated using the first law of thermodynamics:
ΔU = Q - W
where:
ΔU is the net change in internal energy of the system
Q is the heat added to the system
W is the work done by the system
This equation states that the net change in internal energy is equal to the heat added to the system minus the work done by the system.
To find the net internal change in the internal energy of the volume of gas, we need to consider both the energy given off and the work done by the gas.
Given:
Energy given off = 70 J
Work done by the gas = 45 J
The net internal change in the internal energy can be calculated using the first law of thermodynamics:
ΔU = Q - W
Where:
ΔU is the net internal change in internal energy
Q is the heat energy transferred to or from the system
W is the work done by the system
Substituting the given values:
ΔU = 70 J - 45 J
ΔU = 25 J
Therefore, the net internal change in the internal energy of the volume of gas is 25 J.