"Normal" for concentration

[dougkaye]

BR Chem mentions this - never came up during Chem 1,2 and isn't in EK at all - curious if we need to worry about this. For example a 1.0 M diprotic acid solution would be listed as 2.0 normal b/c 2 equivalents of acid. Thanks.

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[Rabolisk]

That's right. 1M of a diprotic acid = 2N concentration > 1M of a monoprotic acid = 1N concentration, reflecting the fact that even though those two acids have the same molar concentration, the diprotic acid has twice the protons, or twice the reactive species (since we are concerned about protons for acids). I'm trying to remember if I've seen this on the MCAT, but regardless, it's not a hard concept to remember, so I would learn it.

 

[dougkaye]

That's right. 1M of a diprotic acid = 2N concentration > 1M of a monoprotic acid = 1N concentration, reflecting the fact that even though those two acids have the same molar concentration, the diprotic acid has twice the protons, or twice the reactive species (since we are concerned about protons for acids). I'm trying to remember if I've seen this on the MCAT, but regardless, it's not a hard concept to remember, so I would learn it.

That's true. and even if the terminology of Normal isn't used, it helps to reinforce that the diprotics need two equivalents of strong reagent to neutralize them in a titration. Thanks!