[jbaden10]

If there were 2 compounds in a mixture, stated at a 1:3 ratio (CH3CN and CH3CH2CN) in CDCl3;

I'm wondering if the excesss amount of the second compound ends up interacting with the hydrogens of the first compound.

[a student]

I really didn't get what's your question exactly, but I think that the hydrogens of these two compounds wouldn't interact with each other because they are not chemically equivalent so they appear in different places and I think that the intensity of the compound which is more than the other in your sample should be more.
I hope I realized your problem correctly.

[Dan]

I'm wondering if the excesss amount of the second compound ends up interacting with the hydrogens of the first compound.

I'm no expert, but here are my thoughts:

I think in this case the concentrations of the two compounds are low enough that any interaction between them is negligible in terms of their spectra. This tends to be the case, practically speaking, in a dilute solution (chloroform-d in this case).

Molecules do interact with each other, and these interactions can effect the spectrum - consider the fact that a given compound can have a considerably different nmr spectrum when run in different solvents, or that acidic an basic molecules will have a pH dependent spectrum.

I suspect that the kind of effect you are referring to could only be noticeable at very high concentration - where the interactions between MeCN and EtCN are stronger. If, for example, you ran pure MeCN for ¹H NMR and then, in a seperate experiment, ran your mixture (again with no solvent), you may see a change in the chemical shift of the MeCN (relative to the internal reference). Consider that you have essentially run a sample of MeCN in two different solvents: in the first experiment the solvent was (also) MeCN, in the second experiment the solvent was EtCN. The effect might still not be noticeable though, you'd have to try it - it would probably be more pronounced if the second component of the mixture was less similar to the first, perhaps MeCN/Benzene or something.

Does that make any sense?