state functions

[Sarah Blake-2I]

Could someone explain to me what a state function is and why that is important? I know enthalpy is a state function but I am not sure why and what its significance is. Thanks!

[Lauren Stack 1C]

A state function is a property that is not dependent on path taken to obtain that state, thus these state properties can be added or subtracted. Some examples given in lecture were E, P, V, T, Density, and Heat Capacity. To further explain this using volume, if you compress a gas in a container using a piston, the difference in the initial and final volume does not depend on how fast/slow the container is compressed. On the other hand, work and heat depend on the path taken between the reactants and products. An example of this would be seen if you imagined two people rock climbing. One person goes up the cliff face directly, while the other backslides a number of times. The person who backslides ends up doing more “work” but the two climbers end up making the same elevation change in the end, so thus work is a path-dependent function and not a state function.

[KnarGeghamyan1B]

State functions are important in thermochemistry because enthalpy, entropy, Gibbs free energy, etc. are all state functions, which is what allows us to add and subtract heat in the equations.

[Amy Kumar 1I]

When is it a state function, you only need to take the initial and final states into consideration instead of all the intermediate pathways as well. This makes it easier to calculate change.

[AKhanna_3H]

State functions can be added or subtracted because it does not matter what path it took to get from the initial value to the final value.