In lab you will be preparing five aqeous solutions of glycerine (C3H8O3), each a

Question

In lab you will be preparing five aqeous solutions of glycerine (C3H8O3), each a different predetermined %(m/m) and each to a total volume of 30 mL.

Part A How many grams of glycerin should you measure to make your 20 %(m/m) solution for lab? Report your answer to three significant figures.

Part B How many grams of deionized water should you measure to make your 20 %(m/m) solution for lab? Report your answer to three significant figures.

Part C What is the molality of this solution? Report your answer to three significant figures.

Explanation / Answer

Part A: 20g of glycerin sholuld be added to 80mL water to prepare 20 %(m/m) solution.

To prepare 30mL of 20 %(m/m) solution amount of glycerin required = (20/80)*30 = 7.500 g

Part B: The amount of dionized water required to prepare 20 %(m/m) solution of 30mL is 30.000g

Part C: molality = (Wt/M.wt) x (1000/Mass of solvent) = (7.5/92) x (1000/30) = 2.717 molal

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