Ch.20 Acids, Bases, And pH
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What is a Bronstead Lowry acid?
A proton donor
What is a Bronstead Lowry base?
A proton accepter
What is a conjugate acid base pair?
Contains two species that can be interconverted by the transfer of a proton
Given an example of a conjugate acid base pair and explain
HCL and CL- In the forward direction, HCL releases a proton to form CL - In the reverse direction CL - accepts a proton to form its conjugate acid HCL
What do the terms monobasic, dibasic, and tribasic acids refer to
The total number of hydrogen ions in the acid that can be replaced per molecule
PH=
-log[H+(aq)]
[H+(aq)]=
10^-PH
strong acid Ka=
[H+] [A-] / [HA] Moldm-3
The larger the numerical value of KA
The further the equilibrium is to the right and the greater dissociation and therefore greater strength of acid
pKa=
-logKa
Ka= (in terms of pKa)
10^-pka
As the value for KA increases what happens to the value of PKA
It decreases
how many x more H+ does a PH of 1 have than 2
10x
PH for strong acid
completely dissociates so [H+ (aq)] = [HA (aq)]
weak vs strong acid equation
weak acid has reversible
pKa and Ka of strong acid
large Ka small pKa
pKa and Ka of weak acid
small Ka large pKa
weak acid Ka =
[H+]^2 / [HA] use full [H+] [A-] / [HA] if asked to write an expression
approximations for the weak acid Ka equation
. [H+] = [A-] small amount of H+ from dissociation of water but it is ignored . eqm conc of HA is less than at start but weak acid so not much dissociation so ignore any change in conc [HA eqm] = [HA start]
Kw
ionic product of water ions in water multiplied [H+] x [OH-]
PH of a strong base
use Kw
PH of weak base
similar to process of weak acid