1.12 Acid and Bases Flashcards
Brønsted Lowrey definitions of Acid and Base
Acid is a proton donor
Base is a proton acceptor
What is a monophonic acid?
Only donates 1 H+
What is a diprotic acid?
Donates 2 H+
H2SO4
Is water an acid or base?
ACID:
Donates H+ to ammonia
H2O + NH3 → OH- + NH4+
BASE:
HCl donates H+ to water
HCl + H2O → H3O+ +Cl-
What is the ionisation of water?
Water is naturally slightly ionised
H2O ⇌ H+ + OH-
What is the ionic product of water?
Kc= [H+][OH-] / [H2O]
Kw= [H+][OH-]
298K its equal to 1*10-4 mol²dm-³
Because each H2O dissociates to 1 H+ and 1 OH-…….
[H+]² = 1*10-4mol²dm-³
What is the pH scale?
-log10 [H+]
The smaller the pH the greater the H+ ions.
[H+]= 10 ^-ph
How do weak acids dissociate and what is Ka?
HA ⇌ H+ + A-
Kc= [H+][A-] / [A] =Ka
Ka is the dissociation constant
How does Ka work with equilibrium?
The larger the value of Ka, the further equilibrium is shifted to the right, the stronger the acid
What is PKa?
It’s a similar scale to pH
-log(Pka
Why do we use titration for acid and bases?
we use titration to find out when we have neutralised acid-base reaction.
What is the endpoint?
The position at which indicator changes colour
What is the equivalence point?
This refers to the stoichiometric quantities of the reactant.
IMAGES OF ACID BASE CURVES
IMAGES OF ACID BASE CURVES
What is litmus?
Weak acid
Unionised is red
Ionised is blue
HLit ⇌ H+ + Lit-
What is Methyl Orange?
MeOr
Benzene in structure
Acid is red
Alkalis yellow
HMeOr ⇌ H+ + MeOr-
What is phenolphthalein?
Weak acid
Acid is colourless
Alkali is purple
H Phph ⇌ H+ + Phph-
Think P for Phph & Purple
What is an acidic buffer?
The weak acid and a salt of the weak acid
CH3COOH ⇌ CH3COO- + H+
How does an acidic buffer work?
CH3COOH ⇌ CH3COO- + H
If acid is added the increased H+ is mopped up by CH3COO-
If alkalis is added equilibrium shifts to the right to replace the H+ lost
