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Posted: Thu Jan 10, 2019 5:01 pm
What is activity? I understand that we use conc. as an approximation in calculations, but what is the relationship between activity and concentration?
Posted: Thu Jan 10, 2019 5:24 pm
I have the same question, all I got from lecture is that it's unit-less and that the concentrations we use are approximations. Does anyone understand?
Posted: Thu Jan 10, 2019 5:36 pm
In the book, it says activity is "the effective concentration or pressure of a species J expressed as the partial pressure or concentration of the species relative to its standard value". So I think it describes a non ideal, real chemical potential for a solution rather than just an ideal concentration. I am not certain why there are units, however.
Posted: Thu Jan 10, 2019 5:44 pm
Looking online it came up as, "Activity is a measure of the effective concentration of a species under non-ideal (e.g., concentrated) conditions. This determines the real chemical potential for a real solution rather than an ideal one."
I think activity is the concentration (either in molarity or partial pressure) in the actual experiment, not the calculations (ideal one). The ideal ones would be the theoretical calculation concentrations whereas activity is the empirical concentrations. Hope this helps!