posted by Steve on .
A student placed 12.0g of glucose (C6H1206) 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 50.0-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?
12.0 g/100 mL 0riginal.
Take a 50.0 mL aliquot so now you have 6.0 g in the 50.0 mL. That is diluted to 500 mL so now you have 6.0 g in 500 mL. If you take 100 mL of that solution you will have 1/5 of 6.0 = ??
Molar Mass= 180.18
n= m/MM= 0.067 moles.
Molarity= n/V= .067/.1= .67
M1V1=M2V2 => 0.67(.05)=M2(.5)
Solve for M2 and you get .067
M= m/VMM : Molarty= mass/ Volume x Molar Mass
so m= MVMM : mass= Molarity x Volume x Molar Mass
m= .067(.1)(180.18)= 1.21
Just the steps to Dr.Bob's work :)