A2 acids and bases. Flashcards
Acid + base.
Salt and water.
Acid + carbonate.
Salt, water and CO2.
Acid + metal.
Salt and hydrogen.
Base definition.
Neutralises an acid to form a salt.
Alkali definition.
A base that dissolves in water releasing OH- ions.
Salt definition.
A substance produced by the reaction of an acid with a base.
Bronsted-lowry acid and bases definition.
Acid- proton donor
Base- proton acceptor.
Conjugate acid base pairs definition.
2 species that can be intro converted by the transfer of a proton.
Monobasic, dibasic and tribasic acids.
Refer to the total number of hydrogen ions that can be replaced per molecule in an acid-base reaction.
What type of scale is the pH scale?
Logarithmic as each increase/decrease in number means a 10x difference.
Conversion between H+ and pH values.
pH= -log(H+)
10^-pH= H+.
Calculating the pH of strong acids.
Can be calculated directly from the H+ concentration.
Kw definition.
The ionic product of water
(H+) x (OH-)
1.00 x 10^-14 mol2dm-6.
How to calculate weak and strong base pH.
Weak= similar to weak acid
Strong= using Kw and OH- concentration.
Weak acid dissociation equation.
HA–> H+ + A-.
Ka expression.
(H+)(A-)/(HA)
Used for weak acids
Acid dissociation constant.
What does a large value of Ka indicate.
The equilibrium is more towards the right= greater dissociation= greater acid strength.
Converting between pKa and Ka.
pKa= -logKa
10^-pKa=Ka.
Relationship between acid strength, pKa and Ka.
Stronger acid= large Ka= smaller pKa
Weaker acid= small Ka= larger pKa.
Approximations assumed when calculating the pH of a wrak acid using Ka.
1) That the H+ conc from the dissociation of water is so small that it can be neglected
2) As the dissociation of weak acids is small, it is assumed that there is no decrease/can be neglected in the HA concentration from dissociation.
Ka simplified expression used for weak acids w/ the assumptions.
(H+)^2 eqm /HA start.
