krio Posted August 29, 2010 Share Posted August 29, 2010 Why acids have a small pK value while bases have a higher pK value ? Link to comment Share on other sites More sharing options...
cypress Posted August 29, 2010 Share Posted August 29, 2010 (edited) I assume when you ask about pK you mean pKa. pKa is small for acids because of the definition. Ka = [H+][A-]/[AH] and pKa = -log10Ka so the greater the disassociation to H+ and A- the smaller the pKa, therefore acids have smaller pKa's than bases. Note that bases have smaller pKb's where Kb = [HB+][OH-]/ and pKb = -log10Kb Edited August 29, 2010 by cypress Link to comment Share on other sites More sharing options...
mississippichem Posted August 30, 2010 Share Posted August 30, 2010 Don't forget that [math]K_w =[K_a ][K_b ] [/math]. So Ka and Kb must be inversely proportional. Link to comment Share on other sites More sharing options...
John Cuthber Posted August 30, 2010 Share Posted August 30, 2010 Are you just wondering why the scale is "the wrong way up"? with strong acids getting a small number? If so that's because they chose to get rid of the minus sign. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now