posted by margrav2 on .
Prepare 600mL of a 100mM solution of glucose in 0.9% NaCl. Also need to prepare the 0.9% NaCl solution.
And the 0.9% is w/w, w/v, ??
it doesn't say but I'm assuming its w/v
Is this an isotonic something or other?
I'm not sure the only help my professor gave for this question is as follows...
Make a liter of 0.9%NaCl in water. The result for grams of NaCl to add to the water I want in one sig fig. Then use 600 mL of the 0.9% NaCl you prepared as the solvent to make a 100mM Glucose solution. Amount of glucose required is expressed in 3 sig figs. This is how this solution would likely be prepared in most labs.
Yes, a 0.9% NaCl w/v is an isotonic solution.
Your prof wants 1L so wouldn't 0.9 g NaCl/100 mL solution be correct or 9 g/L of soln? That gets your 1 L of 0.9% w/v NaCl.
Look up the molar mass glucose, you want how many moles glucose? That will be---
you want 100 mM which is 0.1M and moles = M x L = 0.1M x 0.6L = xx moles glucose.
moles = grams/molar mass so solve for grams glucose. From your prof's explanation, youy drop about 10.8 g in 600 mL of th solvent and dissolve all of the glucose. This will NOT prepare EXACTLY 100 mM although it will be close. I don't know how much flexibility you have. As an analytical chemist, if someone told me to do this, I would weigh the glucose, drop in a container, and MAKE TO A FINAL VOLUME of 600 mL (although I know 600 mL volumetric flasks are difficult(if not impossible) to come by). If I couldn't find one I would make up a L of solution or 500 mL of solution for which volumetric flasks are available. Anyway, you get the idea. I suspect, although I don't know, that the volume will change so little by adding about 11 g glucose that the osmotic pressure will be essentially isotonic with the solutions to be analyzed.
Dr. Bob seriously you have saved me and I am very thankful that there are people like you out there who wish to help others!!!!!