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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: hiswifetheirmom on November 18, 2009, 09:33:28 PM

Title: Which is the stronger acid??
Post by: hiswifetheirmom on November 18, 2009, 09:33:28 PM

Which acid in each pair is stronger?

A)  CH3COOH  or  HPO4-2

B)  HCO3- or HCN

Title: Re: Which is the stronger acid??
Post by: BetaAmyloid on November 18, 2009, 09:40:23 PM

CH₃COOH and HCN are the stronger acids.

The pK_a values for CH₃COOH compared to HPO₄^-2 is much lower making it a stronger acid. pK_a values for HCO^3- and HCN are extremely close, but HCN is a little bit less, again, making it a stronger acid.

pK_a relates to the ability of an acid to dissociate causing it to become "stronger" or "weaker."

:)

Title: Re: Which is the stronger acid??
Post by: hiswifetheirmom on November 18, 2009, 09:46:26 PM

Wonderful!!  I get it now!  Thank you for your help.  :)

Title: Re: Which is the stronger acid??
Post by: BetaAmyloid on November 18, 2009, 09:51:49 PM

You're welcome.

To clarify - higher pK_a means lower dissociation which means weaker acid; lower pK_a means higher dissociation which means stronger acid.

 :)