3.31 AS Inorganic Chemistry - Preparation of volumetric solutions

Volumetric analysis

volumetric flasksVolumetric analysis is the determination of an unknown solution by reaction with a solution of known concentration. The apparatus used is standard glassware.

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Preparation of a standard solution

Primary standards

A primary standard is a compound which has the following characteristics:


Example: Preparation a standard solution of sodium carbonate

Sodium carbonate has the formula Na2CO3. It has a relative formula mass of 106

If we wish to prepare 250 ml of a 0.1 mol dm-3 solution then we need a total of 0.25 x 0.1 = 0.025 moles = 0.025 x 106 g = 2.65 g

Approximately 2.65 g is accurately weighed on an electronic balance in a weighing bottle.

The sodium carbonate is transferred into a 250 ml volumetric flask and about 100 ml of deionised water is added, rinsing out the weighing bottle.

The mixture is shaken in the volumetric flask until the sodium carbonate dissolves.

Deionised water is added to the volumetric flask up to the mark.


AS Inorganic Chemistry Experiments

Task Possible context
Make up a volumetric solution The preparation of a standard solution of sodium carbonate
Carry out a simple acid-base titration Determine the concentration of unknown hydrochloric acid by titration
Carry out some inorganic tests Tests for anions

AS Physical Chemistry Experiments

Task Possible context
Measure an enthalpy change Use Hess's law to find an unknown enthalpy change, such as the reaction of anhydrous copper(II) sulfate with water to produce hydrated crystals
Determine the Mr of a volatile liquid or the Mr of a gas Determine the Mr of hexane or the Mr of carbon dioxide
Investigate how the rate of a reaction changes with temperature. Investigate the rate of reaction of sodium thiosulfate with acid at different temperatures

AS Organic Chemistry

Task Possible context
Distil a product from a reaction The preparation of ethanal from the oxidation of ethanol or the preparation of cyclohexene from the dehydration of cyclohexanol
Carry out some organic tests Tests for alkene, alcohol, acid, aldehyde
Investigate the combustion of alcohols Use a calorimetric method to measure the enthalpies of combustion in an homologous series of alcohols