So far, we"ve been thinking about how one molecule could connect with another molecule of the very same compound to type a liquid or a solid. What about two different compounds? It turns out the whether two different compounds connect with each various other depends top top the same kinds of interactions we have looked at so far.

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Two liquids that execute not really mix fine together, such as oil and also water, are defined as immiscible. 2 liquids that appear to mix completely together are claimed to it is in miscible. Water and ethanol room one example of a pair that miscible liquids, since you can take any amount of ethanol and mix that with any type of amount that water and also you will constantly end up through a clear, colorless liquid similar to the ones you started with.





Exercise (PageIndex4)

Explain, in terms of intermolecular forces, why ethanenitrile and hexane space not miscible.

Answer

This difficulty is comparable to the previous one, yet in this case the attraction in between the solid dipoles that the nitrile groups would be too lot to overcome.


Sometimes, the attractions in between molecules room a little an ext complicated. 2 molecules may have various interactions on your own, but when inserted together still regulate to interact with each other. Because that example, dichloromethane and hexane mix together pretty well.

How deserve to that be? Dichloromethane has dipole interactions. Hexane has actually nothing an ext than London interactions. Ethanenitrile and hexane didn"t mix for that an extremely reason. But the trouble was no whether those two molecules could interact with each other; they could. The trouble was that ethanenitrile would not offer up that dipole-dipole interactions because that the little amount it can gain through mixing through hexane.

In this case, the dipoles between dichloromethane are lot smaller; they aren"t held back from the hexane molecules as strongly. Top top the various other hand, the interaction in between the the hexane and also dichloromethane is actually enhanced a tiny bit. Whereas hexane molecules rely exclusively on weak, transient London interactions to cling to each other, dichloromethane has actually a permanent dipole. That irreversible dipole is maybe to enhance the transient dipole in hexane.

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This is called a dipole / induced dipole interaction. The slim tug dichloromethane exerts top top hexane"s electrons in reality helps the two various molecules interact an ext strongly.


Exercise (PageIndex5)

Below are number of solvents and also some possible solutes. For each pair,

i. Attract a solvent molecule communicating with several other (identical) solvent molecules. Brand the strongest intermolecular pressure holding lock together.ii. Attract a solute molecule connecting with several other (identical) solute molecules. Label the the strongest intermolecular force holding castle together.iii. Draw one solute molecule communicating with several solvent molecules. Label the strongest intermolecular force holding them together. Predict whether the solvent will dissolve far-reaching amounts of the solute.A. Solvent = Ethylene glycol (HOCH2CH2OH); Solute = NH3B. Solvent = Pentane (CH3(CH2)2CH3); Solute = triethylamine, <(CH3CH2)3N>C. Solvent = CH2Cl2; Solute = NaCl