Chapter 3 - Volumetric analysis

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CHAPTER 3 - VOLUMETRIC ANALYSIS

volumetric analysis is the amount in mol of the substance being analsyed is determined by: measuring the volume of test solution that reacts completely with a volume of solution with known concentration; analysis using measurement of volume of a known to find an unknown e.g. titration

concentration is a measure of the amount of solute dissolved in a specified volume of solution

molarity (M) is one measure of concentration. It is the amount, in mol, of solute dissolved in one litre of solution. The concentration, c mol L-1, is given by c=n/V where n=number of mole and V=volume in litres

a primary standard has a high level of purity enabling the number of moles to be determined from its mass

a standard solution has a known concentration and is prepared by dissolving a known mass of a primary standard in an accurately known volume of solution

in a titration, a measured volume of a standard solution is reacted with a measured volume of the solution whose concentration is to be determined

the equivalence point of a reaction occurs when the reagents have been mixed in the mole ratio shown by the reaction equation

an indicator may be used to identify the equivalence point of a reaction

the stage at which an indicator changes colour is called the end point

for accurate analysis the indicator end point must closely match the reaction equivalence point

concordant titres vary within narrowly specified limits. Three concordant titres are usually obtained during a titration

HOW IS PRIMARY STANDARD PREPARED???

1. Place a weighed sample in a volumetric flask

2.Half fill with water. Shake until dissolved.

3.Add water to the calibration line. Shake again.

KEY STEPS IN TITRATION CALCULATIONS

1. Balanced equation

2. N of the known

3. N of unknown

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