For the following processes, calculate the change in internal energy of the system and determine whether the process is endothermic or exothermic: (a) A balloon is cooled by removing 0.655 kJ of heat. It shrinks on cooling, and the atmosphere does 382 J of work on the balloon.

Key Concepts

Internal Energy

Internal energy is the total energy contained within a system, encompassing both kinetic and potential energy of the particles. It is a state function, meaning it depends only on the current state of the system, not on how it reached that state. Changes in internal energy can be calculated using the first law of thermodynamics, which states that the change in internal energy equals the heat added to the system minus the work done by the system.

Endothermic and Exothermic Processes

Endothermic processes absorb heat from the surroundings, resulting in a decrease in the temperature of the surroundings, while exothermic processes release heat, increasing the temperature of the surroundings. The classification of a process as endothermic or exothermic is determined by the sign of the heat transfer: positive for endothermic (heat absorbed) and negative for exothermic (heat released). Understanding these concepts is crucial for analyzing energy changes in chemical and physical processes.

Work Done on/by the System

In thermodynamics, work is defined as the energy transfer that occurs when a force is applied over a distance. When work is done on the system, it is considered positive, as it adds energy to the system. Conversely, when the system does work on the surroundings, it is negative. This distinction is important for calculating the overall change in internal energy, as it directly influences the energy balance in the system.