Question

A student placed 18.5 g 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 45.0-ml sample of this glucose solution was diluted to 0.500 l. how many grams of glucose are in 100. ml of the final solution?

Answer 1

100ml= 0,1L

Concentration of glucose = mass/ volume
Concentration=18,5/ 0,100
= 185 g/L

We take away, 0,045 L of that solution, creating another solution with it but with 0,500 L of volume

Concentration of the first solution= C1
Volume of the first solution= V1
Concentration of the second solution= C2 
Volume of the second solution= V2
C1xV1= C2xV2

185 x 0,045= C2 x 0,500
= 16,65 g/L --> this is the concentration of the new solution

The only thing left is to know the mass in 0,100 L

Concentration = mass/ volume
16,65 = mass/0,100
=1,665 grams