QA number:14520

QHow to calculate the concentration of a solution.


The molar concentration expressed in units of mol/l (M) is a widely used concentration method. It is the amount of moles of the target substance (solute) dissolved in 1 liter of solution.
It is calculated as follows:

(weight of 1 liter solution) x (purity) ÷ molecular weight
[specific gravity of solution (g/ml) x 1,000 (ml) x purity (w/w%) / 100 ÷ molecular weight]

For example, let's calculate the molar concentration of 2-mercaptoethanol (HSCH2CH2OH).
The necessary information is organized as follows;

Specific gravity (or density) = 1.114 g/ml purity (or content) = 100 w/w% assumed molecular weight = 78.13
Calculating the value by applying it to the above equation, you can get the molar concentration.
1.114 g/mL x 1,000 mL x 100 w/w% / 100 ÷ 78.13 = 14.26 mol/L

To obtain the concentration like this, you have to know three factors: specific gravity (or density), purity (or content) and molecular weight.
The table below is a quick reference chart of frequently used acids and bases. For acid and alkali, there is a use for "neutralization titration". "Normality (N)" is also often used.


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