5.1.3 - Acids, Bases And Buffers Flashcards
(32 cards)
What are acids?
Proton donors
What are bases?
Proton acceptors
What do H+ ions form in water?
Hydronium ions H3O+
What is the conjugate base?
The species that has lost a proton.
What is a conjugate acid?
Species that has gained a proton.
What are monoprotic acids?
Have only 1 proton they can release into solution.
Acid + alkali
Metal salt + Water
Acid + base
Metal salt + Water
Acid + carbonate
Metal salt + Water + Carbon dioxide
Acid + Metal
Metal salt + hydrogen
What is Ka used to calculate?
The concentration of a weak acid.
The higher the Ka?
The stronger the acid.
The lower the Ka?
The weaker the acid.
Ka =
[H+]^2 / [HA]
pKa =
-log Ka
ph =
-log[H+]
[H+] =
10^-pH
Kw =
[H+] x [OH-]
When a metal has a valency of 1 what does [OH-] =
[MOH]
If you are using a metal with a valency of 2, e.g. calcium what do you need to do to the value of [MOH] to find [OH-]?
Times by 2
What is a buffer?
A solution that as a system minimises pH changes on addition of small amounts of acid or base.
What 2 ways are buffers made?
- weak acid with the salt of its conjugate base.
- mix of an excess weak acid with a strong alkali.
In the buffer CH3COOH H+ + CH3COO- what happens when you increase H+ ?
The extra H+ ions combine with the CH3COO ions, causing the equilibrium to shift to the left reducing the concentration of H+.
In the buffer CH3COOH H+ + CH3COO- what happens when you increase OH- ?
OH- ions react with the H+ ions forming water, removing H+ ions. This causes CH3COOH to dissociate to form H+ ions # shifting the equilibrium to the right.
