state vs. not-state functions?

[bananaboat]

Advertisement - Members don't see this ad

what is makes a state function a state function?

what is an example of a non-state function

thanks 🙂

 

[deleted106503]

Hope this helps for examples of state functions. Scroll up for definitions. http://en.wikipedia.org/wiki/State_function#Examples

 

[nikorette]

If final - initial is all that matters it is a state function. These are also called "path independant". So something like friction is not a state function where gravitational potential energy is. Make sense?

 

[DrWanahbe]

state function - it doesn't matter the path you take to get there, you will always arrive at the same spot.

Example: If I want to have $1000 in my bank account, I can add 200/week until I have $1000 or I can add $750 one week, $500 the next week, and then take out $250 and I'll still have $1000. No matter which way I did it, I still have the same ending amount.

Non-state function - the path you take makes a difference in where you want to end up or what the values will be.

Example: The distance between two cities depends on the path you take. You can take a direct route and be there in 20 miles or you could take a bunch of side roads and be there in 50 miles. Your distance traveled will be different in each case.

In terms of chemistry, pressure, volume, temperature are all state functions. Heat and work are not considered state functions individually, but their sum, delta E, is.

 

[bananaboat]

state function - it doesn't matter the path you take to get there, you will always arrive at the same spot.

Example: If I want to have $1000 in my bank account, I can add 200/week until I have $1000 or I can add $750 one week, $500 the next week, and then take out $250 and I'll still have $1000. No matter which way I did it, I still have the same ending amount.

Non-state function - the path you take makes a difference in where you want to end up or what the values will be.

Example: The distance between two cities depends on the path you take. You can take a direct route and be there in 20 miles or you could take a bunch of side roads and be there in 50 miles. Your distance traveled will be different in each case.

In terms of chemistry, pressure, volume, temperature are all state functions. Heat and work are not considered state functions individually, but their sum, delta E, is.

nice explanation...sort of like total distance is path dependent, but displacement is not.

 

[DrWanahbe]

For some reason, I'm not grasping what you mean by displacement. Do you mean in something like an exchange reaction?

But yes, distance traveled is path dependent.

 

[bananaboat]

For some reason, I'm not grasping what you mean by displacement. Do you mean in something like an exchange reaction?

But yes, distance traveled is path dependent.

well its just analogy.

like if you travel from new york to LA your displacement is the same (x number of miles between the two cities). but your distance travelled could be variable, depending on the path taken.

 

[DrWanahbe]

Hmmm...I'm not sure. The distance between the two can always be measured differently, unless you're just talking a straight line between the two. But I think even that could have variance in measurement.