Physical Chemistry: Partial Molar Volumes NaCl Solutions

[tam]

I'm actually taking a physical chem course and i have to hand in a report onpartial molar volumes in NaCl solutions...I'm not really sure how the concept works and I'm wondering if anyone could clarify! Thanks

 

[so-crates]

Heh, just did this lab, so let's see if I can help.

The idea with partial molar volumes is that when you mix a certain volume of some substance with a certain volume of another, the total volume in many cases is not simply V(A) + V(B). The total volume can be represented by the equation $$V~=~n_1\overline{V_1}~+~n_2\overline{ V_2}$$, where V is the total volume, n1 and n2 are the quantities of the mixture in moles, and V1 and V2 are defined as the partial molar volumes of the components of the mixture.

We mixed alcohols and water, and its a little different for salts, though I suppose the principle is basically the same.

 

[ravenprp]

Sure, I'd be happy to clarify the concept of partial molar volumes in NaCl solutions for you. In physical chemistry, partial molar volumes refer to the change in volume of a solution when a small amount of a specific component is added or removed while keeping the overall composition and temperature of the solution constant. In the case of NaCl solutions, this means measuring the change in volume when a small amount of NaCl is added or removed from the solution.

The partial molar volume is an important concept in understanding the behavior of solutions, as it can help us understand how the interactions between different components affect the overall volume of the solution. In the case of NaCl solutions, the partial molar volume of NaCl is affected by the interactions between the Na+ and Cl- ions, as well as the interactions between the ions and water molecules.

To calculate the partial molar volume, we use the equation:

Vm = (V2 - V1) / n2 - n1

Where Vm is the partial molar volume, V2 is the volume of the solution with the added component, V1 is the volume of the solution without the added component, n2 is the number of moles of the added component, and n1 is the number of moles of the original solution.

In your report, you can discuss the factors that affect the partial molar volume of NaCl solutions, such as temperature, concentration, and the nature of the solvent. You can also include any experimental methods used to measure the partial molar volume and provide data to support your findings.

I hope this helps clarify the concept of partial molar volumes in NaCl solutions for you. Good luck with your report!