Concentration (Edexcel GCSE Chemistry)
Revision Note
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Calculating Concentration
A solid substance that dissolves in a liquid is called a solute, the liquid is called a solvent and the two when mixed together form a solution
Most chemical reactions occur between solutes which are dissolved in solvents, such as water or an organic solvent
Concentration simply refers to the amount of solute there is in a specific volume of the solvent
The greater the amount of solute in a given volume then the greater the concentration
A general formula for concentration is thus:
Concentration can be measured in grams per cubic decimetre
1 decimetre cubed (dm3) = 1000 cm3
1 decimetre cubed (dm3) is the same as 1 litre
You may be given data in a question which needs to be converted from cm3 to dm3 or the other way around
To go from cm3 to dm3 :
Divide by 1000
To go from dm3 to cm3 :
Multiply by 1000
Worked Example
A student dissolved 10 g of sodium hydroxide, NaOH, in 2 dm3 of distilled water. Calculate the concentration of the solution.
Answer:
Examiner Tips and Tricks
Be careful when doing volume unit conversions as it is easy to multiply instead of dividing by 1000 and vice-versa. Always ask yourself – is the result going to be a bigger or smaller number than I started with? Do I get more or fewer cubic decimetres when I convert from cubic centimetres?
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