Calculating dilutions and concentration

Dilutions

If you need to dilute a stock solution, the formula to use is:

V1C1=V2C2

where V1 is the volume of the stock solution, and C1 is its concentration

and V2 is the final volume you are making, and C2 is the final concentration you want.

 

Concentrations

% concentration, there are 2 possibilities:

1) % per weight, which is used only for solids. x% = x grams of solute/100 ml total volume

2) % per volume, which is used only for liquids. X% = x ml of solute/100 ml total volume

    If you need to calculate a % per weight or a molar concentration of a liquid solute, then you have to find out the density of the solution you will      dilute, or measure it (i.e. weigh 1 ml or so).

3) Molar concentration

    # moles / 1 liter of solution

    #moles of x grams of a substance is: x grams/molecular weight (molecular weight is expressed in grams/mol)

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