Question

You dissolve the sample of fd&c red 40 (molar mass 496.4200 g/mol) in enough water to make 250.0 ml of solution. we call this the stock solution. what is the concentration of the stock solution in terms of molarity?

Answer 1

Molar mass 496.4200 g/mol

Number of moles:

40 g x 1 mol / 496.4200 => 0.08057 moles

Volume in liters:

250.0 mL / 1000 => 0.25 L

Therefore:

M = moles / V

M = 0.08057 / 0.25

 = 0.32228 M

hope this helps!