Study Guide:    Moles, grams, concentration and dilution

book cover Produced by Graham Currell, University of the West of England, Bristol, in association with:
Royal Society of Chemistry, 'Discover Maths for Chemists' website
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Essential Mathematics and Statistics for Science, 2nd Edition
   Graham Currell and Antony Dowman, Wiley-Blackwell, 2009

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This study unit aims to develop the skills for handling units in science. This is achieved by a series of video tips and associated QVA tutorials - questions with video worked answers.


Why do chemists use both mass (e.g. in grams) and 'numbers of moles' to describe the amount of a material?
It is important to realise that a 'mole' describes a specific number of atoms or molecules (depending on whether it is an element or compound), just as a 'dozen' eggs describes a specific number of eggs. This number is important when combining reagents in a reaction, just as the number of eggs is used as the amount of eggs in a given recipe.
It is also necessary to use mass as this is the method by which amounts of the material are measured on the laboratory scale. It is important to be able to convert easily between moles and grams!

Moles and grams
QVA tutorial

Calculating concentrations
QVA tutorial 

Performing dilutions
QVA tutorial

Errors and uncertainties in concentrations and dilutions
QVA tutorial
Additional material ‘EURACHEM Guide: "Quantifying Uncertainty in Analytical Measurement"’ (pdf file)

 Any comments, corrections or suggestions welcome -