How many moles of glucose is in your starting solution? How many moles are there after dilution? So, using the MW of glucose, with that many moles, how many grams do you have?
Sorry enahs, but it doesn't make sense to go through moles here. You start with mass, you end with mass, you should go using mass in the middle. Moles will only add to the confusion.
I disagree that it will be more confusing. After you make the first solution, and then you take 20mL of that. So now instead of doing the simple dilution calculations and using molecular weight, as the teacher and book should have shown numerous times, if you use mass you are assuming he/she is good with percentages, and then again in the end. Which they really
should be good with percentages though. But I would rather assume they have been shown dilution calculations instead of percentages in a Chemistry class!
But, along with how many moles in your starting solution, I was intending to imply concentration.