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Calculate molarity when volume and mass of solute is given

Submitted by Anonymous (not verified) on Sun, 01/23/2011 - 11:15

so i'm not sure how to do this problem can someone please help?

An .085-L aqueous solution contains 7.54 g iron(II) chloride (FeCl2). Calculate the molarity of the solution. Calculate the amount of solute.

Use atomic masses to find the molar mass of FeCl2
eg for CaBr2, using Ca=40 and Br=80, the molar mass = 40 + 80x2 = 200g
So 1 mole has a mass of 200g
If you had 20g you would have 20/200 = 0.1 moles as number of moles = mass/molar mass

Once you molar mass, molarity = number of moles/volume in litres
So if you had 0.1 mole in 0.50L, the molarity would be 0.1/0.50 = 0.2M

Apply this to your example