IIT JEE , AIEEE Forum - Chemistry , Physical Chemistry

brijesh

Why do we consider common ion effect of HCl on H2O & not of H2O on HCl in case of when ph of HCl is 7?

iam_quantized

ur question seems quite illogical.....common ion effect(CIE)... causes supression of weaky dissosiated substance due to presence of other substances (completely dissociated) containing a common ion.here HCL is completely dissosiated in polar solvents(water) whereas water is weakly dissosiated thts y it affects it diss. water cant effect the diss of HCL bcoz it is itself weakly diss...whtever be the sorce of common ion will not effect the diss of a strongly diss subs ...it will always be completely diss.....GOT IT!

smriti.mathur

There is always a common ion effect of strong electrolyte on weak electrolyte. HCl is a very strong electrolyte and H₂O is a very poor electrolyte.

srini

Well.......I think becuse wen the ph of hcl is around7,the concentration of H⁺ions is of the order 10^-7 and so the effect of H⁺ ions in H₂O (where the concentratin of H⁺ ions is 10^-14)considerable.

this is it.

psst......did i get your question right?

arun-rashi

when we mix some strong electrolyte like HCl in some weak electrolyte like H2S both have one ion common so as the common ion concentration increases equilibrium of weak electrolyte goes in backward direction and no effect on strong electrolyte because it again fully ionise.so when we mix water with HCl there is no effect on HCl of common ion effect.

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