# Calculating Change in Internal Energy of a System

## How can we calculate the change in internal energy of a system?

Given that a system releases 617 kJ of heat and does 135 kJ of work on the surroundings, how do we determine the change in internal energy of the system?

## Calculating Change in Internal Energy

The change in internal energy of a system can be calculated by subtracting the work done on the surroundings from the heat released. In this case, the change in internal energy is 482 kJ.

The change in internal energy (ΔU) of a system can be determined using the First Law of Thermodynamics, which states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system:

**ΔU = Q - W**

In the given scenario, the system releases 617 kJ of heat (Q) and does 135 kJ of work (W) on the surroundings. By substituting these values into the equation, we get:

**ΔU = 617 kJ - 135 kJ = 482 kJ**

Therefore, the change in internal energy of the system is 482 kJ. This means that the system has experienced a net increase in internal energy of 482 kJ, considering the heat released and work done on the surroundings.