Section 1: Calculating the Molarity

If you know the number of moles present and the volume of solution that they are in, you can find the molarity of the solution.




What is the molarity of a solution containing 0.05 moles of Sodium Chloride in 250 cm3 of solution? Answer to 4 significant figures.

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The solution is 0.2000 M Sodium Chloride to 4 significant figures.
Molarity =               Number of Moles            
Volume in dm3
250 cm3 = 0.25 dm3

Molarity of Sodium Chloride =          0.05       moles/dm3
0.25

Molarity of Sodium Chloride = 0.2 moles/dm3
Molarity of Sodium Chloride = 0.2000 moles/dm3 to 4 sig figs