What's the difference between HA, H+ and A-??! HELP!

I understand how to use them in calculations, which is quite odd as i can't quite get my head around what they actually are!

Just a simple definition for each would be awesome!

Reply 1

Spacecam

H+ is the acid

A- is the bit "attached to it"

HCl: H+ is H+ and A- is Cl-

Reply 2

EierVonSatan

HA = undissociated acid molecule like CH₃COOH
H+ = short hand for H₃O+
A- = conjugate base of HA, CH₃COO- for example

Reply 3

lilacdilac

so what is the HA bit, is that the acid 'as a whole'?

Reply 4

lilacdilac

ah perfect, cheers guys!

Reply 5

groovyhaz

Yeah:

The HA is the acid - a proton and its conjugate base.

H+ is the proton released when the acid dissociates in water (can also be written as H3O+, the hydroxonium ion)

A- is the conjugate base (i.e. the bit left over after dissociation)