Chemical Forums

Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: cvc121 on January 11, 2018, 12:55:52 AM

Title: Confusion Regarding State and Path Functions
Post by: cvc121 on January 11, 2018, 12:55:52 AM
Hello there.

I am encountering some problems with a question about state and path functions. The question is as follows:

Which of the following is/are state function(s)?
i) The temperature at which dry ice, CO2(s) sublimates at 1 atm of pressure.
ii) The time it takes for one molecule of Cl2(g) to react with one molecule of H2(g) in a gaseous mixture to form two molecules of Hcl(g) under standard conditions.
iii) The amount of work done walking from one building to another.
iv) The amount of heat released by the chemical explosion of nitroglycerin in a bomb calorimeter.

The answer to this question is i) and iv).

I know that state functions are properties that depend only on the current state of a system and not on the way the system acquired that state (i.e. value of a state function does not depend on the path taken or on the rate of change). I also know that path functions are properties that describe the transition of a system from one state to another.

Thus, I understand why situation i) describes a state function but I do not fully understand why iv) is also a state function because heat (q) is a path function.

Does it have to do with the mention of a bomb calorimeter? I know that it is usually assumed that there is no heat exchange with the surroundings when dealing with calorimeters so is this a factor that I should consider?. Also, since a bomb calorimeter is a constant-volume calorimeter and the heat flow in a constant-volume process gives the energy change (ΔE = q), does this make situation iv) a state function because energy is a state function?

Thank you. All help is very much appreciated!
Title: Re: Confusion Regarding State and Path Functions
Post by: Corribus on January 11, 2018, 09:52:37 AM
In a bomb calorimeter, which is constant volume, the heat released is equal to what?