The contents of the closed box in each of the following illustrations represent a system, and the arrows show the changes to the system during some process. The lengths of the arrows represent the relative magnitudes of q and w. (a) Which of these processes is endothermic?

Verified step by step guidance

1. Identify the terms: 'q' represents heat, and 'w' represents work. In thermodynamics, a process is endothermic if the system absorbs heat from the surroundings, meaning q is positive.
2. Examine the arrows: The length of the arrow labeled 'q' indicates the magnitude of heat transfer. A longer arrow pointing into the system suggests a larger amount of heat absorbed.
3. Compare the arrows: Look for the process where the arrow for 'q' is longer and points into the system, indicating a positive q value.
4. Consider the direction: Ensure that the arrow for 'q' is directed into the system, as this signifies an endothermic process.
5. Conclude: Identify the process with the characteristics of an endothermic reaction, where the system absorbs heat, indicated by a positive q value.

Key Concepts

Endothermic Processes

An endothermic process is one that absorbs heat from its surroundings, resulting in a decrease in the temperature of the surroundings. In such processes, the system gains energy, typically in the form of heat (q > 0). Common examples include melting ice or evaporating water, where energy is required to break intermolecular bonds.

Heat (q) and Work (w)

In thermodynamics, heat (q) refers to the energy transferred due to temperature differences, while work (w) is the energy transferred when a force is applied over a distance. The signs of q and w indicate the direction of energy transfer: positive q means heat is absorbed by the system, and positive w means work is done on the system. Understanding these concepts is crucial for analyzing energy changes in a system.

Thermodynamic Diagrams

Thermodynamic diagrams visually represent changes in a system, often using arrows to indicate the direction and magnitude of heat and work. The length of the arrows correlates with the amount of energy transferred, helping to identify whether a process is endothermic or exothermic. Analyzing these diagrams allows for a clearer understanding of the energy dynamics involved in various processes.