State/Path Functions

[Ishkhan 3O]

What is the difference between a state function and a path function? I know that a state function is path independent and path function is path dependent, but what does that mean?

[Glenda Marshall DIS 3M]

When something is path dependent, it means that the method used to reach the final product affects the answer. For example, Dr. Lavelle use the example of two groups climbing a mountain. If one group goes straight up one side, they will exert less energy because they are just powering through and take less time (although I am in no way discounting the strength needed to just hike up a mountain). If another group walks up using switchbacks, it will take them more time to reach the top and thus they will exert more energy. Although both groups reached the same destination (the top of the mountain), the path they took to reach their goal influenced the amount of energy they used. This is what it means to be path dependent (a path function).

However, if you are measuring enthalpy, it does not matter how the heat is absorbed or release, one will always get the same end result. Whether that occurs through one step or 20 steps. It is path independent (a state function) so regardless of what you do with the water and how it is changed, the density will stay the same.

Hope this helped!

[Anuk Burli 2C]

also an important implication of state functions is that according to hess's law a series of reactions of state functions can be summed up to generate a new value for the overall reaction. Examples of these state functions would be enthalpy, entropy, and Gibb's free energy (H, S, and G). However, you are unable to do this for path functions.

[Justin Le 2I]

Two examples of path functions are heat and work, because they describe how the system reached equilibrium, not the system at equilibrium.