Thermochemistry significance of infinitely dilute solution

[Saitama]

Thermochemistry significance of "infinitely dilute solution"

Homework Statement

(see attachment)

Homework Equations

The Attempt at a Solution

I don't know where to start from and it seems to me that data given is insufficient to solve this problem. Also, what's the significance of "infinitely dilute solution"?

Any help is appreciated!

 

[Borek]

Infinitely diluted means all activities equal 1 (so no need for calculations of ionic strength and activity coefficients).

Can't say I understand the question.

 

[epenguin]

Nor me. I'm inclined to say it should be zero for infinitely dilute solutions.

 

[Saitama]

Nor me. I'm inclined to say it should be zero for infinitely dilute solutions.

Is the question wrong then?

 

[epenguin]

Is ΔF_f⁰ defined in your text?

Usually ΔF⁰ 's are defined for a process not a substance, but perhaps there is a convention I am out of date about.

 

[Saitama]

Is ΔF_f⁰ defined in your text?

Usually ΔF⁰ 's are defined for a process not a substance, but perhaps there is a convention I am out of date about.

ΔF_f⁰? No, there is no such thing in my text.

 

[Saitama]

Is ΔF_f⁰ defined in your text?

Usually ΔF⁰ 's are defined for a process not a substance, but perhaps there is a convention I am out of date about.

Can you tell me what does ΔF_f⁰ mean? I will try to look it up somewhere.

 

[Borek]

I wonder if epenguin really means ΔF_f⁰, or did he just misread the problem. F is sometimes used for Helmholtz free energy, but I think question lists ΔH_f⁰ - enthalpies of formation.

 

[epenguin]

Typo from not being able to see original on same screen as typing, I meant ΔH_f⁰

 

[Saitama]

Typo from not being able to see original on same screen as typing, I meant ΔH_f⁰

I know what ΔH_f⁰ means but to solve this question, I think the data is insufficient or am I missing something?

 

[Saitama]

Can I get some more help?

 

[doub]

You have all the info I believe...Look at hess's law and at the net ionic equation. I have posted what I believe the answer to be...

 

[Borek]

Please don't give final answers, that's not how the forum works.

When you mix diluted solutions there will be no precipitate. So while you can be right guessing what the question author had on mind, it is not a correct answer to the question as worded.

 

[epenguin]

I know what ΔH_f⁰ means but to solve this question, I think the data is insufficient or am I missing something?

Can I get some more help?

I don't know what ΔH_f⁰ quite means, I'd have to guess so I can't help. But these questions generally involve a cycle, were the Δ's add up to zero if you go round it, and there is one step you have to find the Δ of when given all the others.