Random and systematic errors in titrimetric analysis

The example of the students titrimetric experiments showed clearly that random and systematic errors can occur independently of one another, and thus presumably arise at different stages of the experiment. A complete titrimetric analysis in 

2 Transferring an aliquot of the standard material to a titration flask with the aid of a pipette. This involves both filling and draining the pipette properly. 

Weighing procedures are normally associated with very small random errors. In routine laboratory work a four-place balance is commonly used, and the random error involved should not be greater than ca. 0.0002 g (the next chapter describes in detail the statistical terms used to express random errors). If the quantity being weighed is normally ca. 1 g or more, it is evident that the random error, expressed as a percentage of the weight involved, is not more than 0.02%. A good standard 

Volumetric procedures incorporate several important sources of systematic error. Chief amongst these are the drainage errors in the use of volumetric glassware, calibration errors in the glassware, and indicator errors. Perhaps the commonest error in routine volumetric analysis is to fail to allow enough time for a pipette to drain properly, or a meniscus level in a burette to stabilize. Pipette drainage errors have a systematic as well as a random effect the volume delivered is invariably less than it should be. The temperature at which an experiment is performed has two effects. Volumetric equipment is conventionally calibrated at 20°C, but the temperature in 

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