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posted by anonymous .
A student placed 10.5g of glucose (C6H12O6) in a volumetric flask, added enough water to dissolve the glucose by swirling, then carefully added additional water until the 100. mL mark on the neck of the flask was reached. The flask was then shaken until the solution was uniform. A 20.0mL sample of this glucose solution was diluted to 0.500 L. How many grams of glucose are in 100mL. of the final solution?
answer in Grams

10.5 g/100 mL = 0.105 g/mL.
You took 20 mL which contains 20 x 0.105 g/mL.
Now you diluted that 20 to 500 so the 500 now contains 20 x 0.105 g/mL = 2.10 g so you now have 2.10/500 mL = 0.00420 g/mL. How much is in 100 mL of that solution?