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A student investigating the properties of solutions containing carbonate ions prepared a solution containing 7.493 g Na2CO3 in a flask of volume 250 mL. Some of the solution was transferred to a buret. What volume of solution should be dispensed from the bret to provide 8.455 mmol Na2CO3? Answer in units of mL.
moles Na2CO3 = grams/molar mass
moles Na2CO3 - 7.493/105.99 = ??
(Na2CO3) = moles/L = ??moles/0.250 = x M.
moles = M x L OR
millimoles = M x mL.
You know millimoles and M, calculate mL.