Problem 29 - Chemistry: The Central Science

Question

(a) What is meant by the term state function? (b) Give an example of a quantity that is a state function and one that is not. (c) Is the volume of a system a state function? Why or why not?

Step-by-Step Solution

Answer

(a) A state function is a property of a system that depends only on its current state, determined by factors such as temperature, pressure, and composition, and is independent of the path taken to reach that state. (b) An example of a state function is internal energy (U), while an example of a non-state function is heat (q) or work (w). (c) Yes, the volume of a system is a state function, as it depends only on the current state of the system and is independent of the path taken to reach that state.

Step 1: Define state function

A state function is a property of a system that depends only on its current state, which is determined by its temperature, pressure, and composition. The value of a state function is independent of the path taken to reach that particular state. In other words, it only depends on the initial and final states of the system, not on the process between those states.

Step 2: Provide an example of a state function and a non-state function

An example of a state function is internal energy (U). The internal energy of a system depends only on its current state, so it is independent of the path taken to reach that state. A quantity that is not a state function is heat (q) or work (w). Both heat and work depend on the path taken during the process, so they are not state functions.

Step 3: Determine if volume is a state function and explain why or why not

The volume of a system is a state function. The volume depends only on the current state of the system, which is determined by factors such as temperature, pressure, and composition, and is independent of the path taken to reach that particular state. This is because the volume of a system is an extensive property that could be calculated by adding up the volumes of any subsystems based on their states, without the need to consider the history or path of how the system reached the given state.