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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: krista07 on September 27, 2008, 01:44:07 PM

Title: Conjugate Bases
Post by: krista07 on September 27, 2008, 01:44:07 PM

I am sure I should've learned this back in general chemistry, but why does the conjugate base have a negative charge? Isn't the acid losing a hydrogen, meaning it would lose one electron and have a positive charge?

One of my homework problems asked us to name the conjugate base for each acid. I was able to find the answers from a chart in the book, but I did not understand why they would all have a negative charge.

Example: The conjugate base of NH3 is NH2-
The conjugate base of H2CO3 is HCO3-

Title: Re: Conjugate Bases
Post by: Borek on September 27, 2008, 02:06:49 PM

It looses proton (H⁺), not hydrogen.

But first of all, conjugate base doesn't have a negative charge, it has charge one less than conjugate acid. For example:

NH₄⁺ (acid) = NH₃ (base) + H⁺

Acid charge = +1
base charge = acid charge - 1 = 1 - 1 = 0

If you start with fully protonated ethylenediamine (C₂N₂H₁₀²⁺ conjugate base will be +1.