Question

A student placed 19.0 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? express your answer numerically in grams.

Answer 1

  moles glucose = 19 g / 180 g/mol= 0.105 
M = 0.105 / 0.100 L = 1.05 

moles in 20.0 mL = 1.05 M x 0.0200 L = 0.0216 

New concentration = 0.0216 /0.500 L = 0.0432 M 
moles in 100 mL = 0.100 L x 0.0432 = 0.00432 

mass = 0.00432 x 180 g/mol= 0.778 g