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A level chemistry
A level chem Module 5
pH and Buffers
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Cards (20)
What is a Bronsted-Lowry acid?
A
proton donor
What is a Bronsted-Lowry base?
A
proton acceptor
What does neutralisation of an acid and a base produce?
A
conjugate acid
and a
conjugate base
General word formula for
acid
and
base neutralisation
HA
(aq) +
B
(aq) >
BH
+(aq) +
A-
(aq)
How to calculate
pH
-log
[
H+
]=
pH
Write the general Ka expression
[
H
+][
A-
]/[
HA
]
How to calculate
pKa
pKa =
-log
Ka
equation for Kw in pure water
[H+][OH]
How to calculate [H+]
[H+]=
10
^
-pH
What is a buffer?
A solution that can
resist pH change
What is in a buffer solution?
A
weak
acid and its
conjugate
base
What does monoprotic mean?
Releases
one
mole of H+ per mole in
solution
Describe how buffers work
-Reduce
large change
-Adding
acid
/bare would shift the
equilibrium
-Acid/base reacts with
OH-
/H+ to form
water
Describe the dissociation of a diprotic acid
1st dissociation =
full
2nd dissociation =
partial
Strong
acid-strong
base pH curve
Equivalence
point =
7
Strong
acid-weak
base pH curve
pH of
1-2
to
8-10
Weak
acid-strong base pH curve
pH of
4-6
to
12-14
Weak
acid-weak
base pH curve
No equivalence
point
How is an indicator suitable for a titration based on the titration curve?
Its
end
point covers
halfway
up the
equivalence
point
How can Ph be measured continuously?
With a
pH probe
AND a
data logger