totally not confusing chem question

[chiddler]

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Which of the following are constant throughout a single phase of any substance or mixture at equilibrium not separated by rigid or adiabatic walls?

I. Temp
II. Pressure
III. Mole fraction

I don't understand what this question is asking.

Thanks.

 

[milski]

Ok, let's try to deconstruct it:

- throughout a single phase - at all temp/pressures where the phase stays the same, for example gas
- any substance or mixture - well, just about anything, no restrictions here
- at equilibrium - not gaining/losing heat, everything is settled
- no rigid walls - volume/pressure are not limited in any way
- no adiabatic walls - heat can be exchanged freely with the surroundings

I. Temp - could we be in the conditions described above at different temperatures? Well, yes, there is a whole range of temps where we can stay at the same temperature, so temp is not constant.

II. Pressure - same logic, there are different pressures at which the system will be as described

III. Mole fraction - this one will stay the same - you cannot change it by changing pressure or changing temp.

So I would go with III. What's the correct answer?

 

[chiddler]

answer is all of them. "The important thing to know here is that temp, pressure, and number of moles is enough to define a phase of a given substance."

adiabatic means no heat exchange, by the way. edit: i just realized that it is not separated by adiabatic walls. Ok I understand your interpretation of this.

 

[chiddler]

bah. I'm feeling apathetic. Forget this question. It's playing with what a phase constitutes which is not difficult anyway.

nevermind.

 

[milski]

answer is all of them. "The important thing to know here is that temp, pressure, and number of moles is enough to define a phase of a given substance."

adiabatic means no heat exchange, by the way. edit: i just realized that it is not separated by adiabatic walls. Ok I understand your interpretation of this.

I understand their answer but I don't interpret their question to be asking that. Oh well. TBR?

 

[chiddler]

EK1001's. yes, the answer is the gist of what they wanted to get across. i think that's enough.

thanks for your help.

 

[MedPR]

Which of the following are constant throughout a single phase of any substance or mixture at equilibrium not separated by rigid or adiabatic walls?

I. Temp
II. Pressure
III. Mole fraction

I don't understand what this question is asking.

Thanks.

We actually spent a good amount of time learning the exact definitions of this kind of stuff in the gen chem class I just took.

A "mixture" can be homogenous or heterogenous. If the entire mixture is in a single phase, however, it is considered homogenous. So, in a homogenous mixture you would expect every property to be the same throughout.

It looks like you guys already have this figured out, but I thought I might as well add that in just in case it helps.

 

[milski]

We actually spent a good amount of time learning the exact definitions of this kind of stuff in the gen chem class I just took.

A "mixture" can be homogenous or heterogenous. If the entire mixture is in a single phase, however, it is considered homogenous. So, in a homogenous mixture you would expect every property to be the same throughout.

It looks like you guys already have this figured out, but I thought I might as well add that in just in case it helps.

It's the interpretation of the exact wording of the question that I don't get. "Throughout a single phase" for me implies that we are talking about all the states when the mixture is a gas, etc. But I'm fine with the concepts and the question is a bit of whatever at this point.

 

[bajoneswadup]

Wouldn't be temp b/c thats the only thing that changes
Keq
oh nvm