Isotonic sodium chloride solution contains 0.9% w/v sodium chloride. If the E-value of boric acid is 0.52, what is the percentage strength (w/v) of an isotonic solution of boric acid?

Answer 1

Hi Jensen B., yet again!

So I looked up E-value, which you could have done? ==> 0.52 g H3BO3 (in solution) have same osmolality as 1 g NaCl (in solution). And you know it's odd, but an on-line source indicates that NaCl is only 0.8 dissociated in isotonic solution. I believe you were quoted 0.9 in a previous question? That's a significant difference! You should do some literature searching to clarify.

However, you don't need that at all here, since E-value is a weight comparison thing. So just ratio across:

0.9% * 0.52w/1w = 0.468% w/v of H3BO3 .

And Jensen, it's not necessary to post all your pharmacy course questions all at once on Wyzant, in fact it's rather discouraged, since it suggests that you're looking for answers rather than to acquire enough knowledge to complete the rest of the assignment yourself. If you are really clueless on this material, please find a regular tutor to coach you for a while until you're up to speed.

-- Cheers, --Mr. d.