Acids, Bases and pH Flashcards
What are Brønsted-Lowrry acids?
Proton donors- they release hydrogen ions when they’re mixed with water.
HA(aq) + H2O —> H3O^+(aq) + A^-(aq)
What are Brønsted-Lowry bases?
Proton acceptors- when they’re in solution, they grab hydrogen ions from water molecules.
B(aq) + H2O(l) —> BH^+(aq) + OH^-(aq)
What is an alkali?
A soluble base
What do strong acids do in water?
Dissociate almost completely. Nearly all H^+ ions will be released.
(Hydrochloric acid)
HCl —> H^+ + Cl^-
What do strong bases do in water?
Ionise almost completely
(sodium hyrdroxide)
NaOH —> Na^+ + OH^-
What do weak acids do in water?
Slightly dissociate- only small numbers of H^+ ions are formed.
e.g. Ethanoic acid and citric acid)
CH3COOH <==> CH3COO^-(aq) + H^+(aq)
What do weak bases do in water?
Slightly ionise- equilibrium lies to the left.
NH3 + H2O <==> NH4^+ + OH^-
What are transferred when acid and bases react?
Equation?
If you add more HA or B, which way to does equilibrium shift?
Protons
HA(aq) + B(aq) <==> BH^+(aq) +A^-
The position of equilibrium moves to the right.
What does H2O act as when an an acid is added to it?
Acts as a base and accepts the proton
HA + H2O <==> BH^+ + a^-
How much does water dissociate?
Slightly, into hyrdoxonium ions and hydroxide ions. Equilibrium lies to the left- there’s so much more water compared to the ions that concentration is considered to have a constant value
H2O <==> H^+ + OH^-
What is the ionic product of water?
Kw = [H^+][OH^-]
At 298K, Kw = 1.00 X 10 ^-14 mold^2 dm^-6
In pure water, what does Kw equal?
Kw= [H^+]^2
there’s one H^+ ion for each OH^- ion.
What does the pH scale measure?
the Hydrogen ion concentration
1) How to calculate pH?
2) How to calculate H^+?
1) -log[H^+]
2) 10^-pH
H^+ =concentration of hydrogen ions in a solution.
What does the term monotonic acid mean?
Each molecule of a strong acid will release one proton when it dissociates. This means one mole of acid produces one mole of hydrogen ions. So H^+ will be the same as the acid concentration.
