Calculation of molar conductance at infinite dilution

[Zayan]

Homework Statement

At25C, the molar conductances at infinite
dilution for the strong electrolytes
NaOH, NaCl and BaCl2are
248x10^-4,126x10^-4 and
280x 10^-4Sm mol1 respectively,
XmBa(OH)2 in Sm mol-1 is

Relevant Equations

Using algebra

The answer given is 524*10^4. The process used is by adding/subtracting the values given. But my concern is that isn't molar conductivity an intensive property? And it hence can't be added. So how is it added and the answer obtained.

 

[mjc123]

Who says intensive properties can't be added? How is the total pressure of a gas mixture related to the partial pressures of its components?

 

[Zayan]

Who says intensive properties can't be added? How is the total pressure of a gas mixture related to the partial pressures of its components?

Partial pressure times the mole fraction is added to get total pressure. Not partial pressure separately. Intensive properties can't directly algebraically be added so why is it here?

 

[mjc123]

Not so. If the partial pressure of oxygen is 0.2 bar, and the partial pressure of nitrogen is 0.8 bar, the total pressure is 1 bar.

You are perhaps thinking of P_i = x_iP_tot
But P_tot = P₁ + P₂
= x₁P_tot + x₂P_tot

But P_tot ≠ x₁P₁ + x₂P₂

 

[Zayan]

Oh you're right but why does my textbook and even google say that intensive properties (like electrode potential) can't be algebraically added or subtracted

 

[mjc123]

Without a context, I can't say.

 

[Borek]

Looks a bit like answer from ChatGPT: definitive, authoritative, polite - and incorrect

 

[Zayan]

So

Looks a bit like answer from ChatGPT: definitive, authoritative, polite - and incorrect

Do you mean intensive properties can be added? If yes, what are the conditions?

 

[Borek]

Do you mean intensive properties can be added? If yes, what are the conditions?

From the quick googling you are not the first to ask that question and the discussion is not new, problem is with the division extensive/intensive which is not as good and clear as it sounds to be. Compare Redlich, "Intensive and Extensive Properties" J. Chem. Educ., 1970, 47 (2), 154–156 (can be found as a downloadable pdf).