1.9 acid base titrations

Question 1

general reactions

Answer 1

The general reactions studied are:
acid + alkali  salt + water
acid + metal carbonate  salt + water + carbon dioxide
acid + ammonia  ammonium salt

Question 2

neutralisation of acid and alkali

Answer 2

The acid + alkali neutralisation equations above can all be represented by the ionic
equation for neutralisation:
H+(aq) + OH-
(aq)  H2O(l)

Question 3

acid and metal carbonate

Answer 3

Acid and metal carbonate
hydrochloric acid + sodium carbonate
The acid + metal carbonate reactions can all be represented by the ionic equation:
2H+(aq) + CO32-
(aq)  H2O(l) + CO2(g)

Question 4

acid and ammonia

Answer 4

The above reactions can be represented by the ionic equation:
NH3(aq) + H+(aq)  NH4+(aq)

Question 5

an acid

Answer 5

An acid is a substance which dissolves in water to produce hydrogen ions (H+).
A weak acid is one which partially dissociates in solution:
CH3COOH  CH3COO- + H+
A strong acid is one which completely dissociates in solution:
HCl  H+ + Cl-

Question 6

an alkali

Answer 6

An alkali is a substance which dissolves in water to produce hydroxide ions (OH-).

Question 7

neutralisation

Answer 7

Neutralisation occurs when the hydrogen ions of an acid cancel out the hydroxide
ions of an alkali:
H+(aq) + OH-
(aq)  H2O(l)

Question 8

the end point

Answer 8

The end point is where the indicator changes colour and the titration is stopped
because the correct amount of acid and alkali have been added and the reaction is
ove

Question 9

what is a titration

Answer 9

A titration is a method of volumetric analysis and involves adding a solution of
known concentration from a burette to a solution of unknown concentration until the
reaction is complete.

Question 10

what is the titre

Answer 10

The titre is the volume of solution used from the burette.

Question 11

preparing a burette

Answer 11

Preparing a burette
 Rinse the burette with deionised/distilled water and then with a
little of the solution it is to be filled with and discard the rinsings.
 Fill the burette with the solution, to above the zero mark, run out until
the bottom of the meniscus is on the zero mark at eye level – this
ensures that the tap/jet is filled.
A meniscus is the curved surface at the top of a column of liquid.