posted by Titania
The molecular mass of glucose is 180g/mol. you prepare a stock solution of glucose, by dissolving 1.8g of glucose in water to a final volume of 1.0L. The stock solution was then diluted as follows:
a. 50mL of the stock solution is added to 450mL of water,
b. and then 1.0mL of the diluted solution is added to 99mL of water. what is the μM concentration of the final solution?
1.8 g glucose/180 = 0.01 mole.
So 0.01 mole/L is the stock soln.
a. 0.01M x (50 mL/500 mL) = ?M
b. ?M x (1.0 mL/100 mL) = x M or x*1000 uM.
Technically, one cannot calculate values for a or b because volumes are not additive; however, since the concn is so low the difference is small enough it can be neglected. The correct way of doing this is
a. Add 50 mL of the stock solution to a 500 mL volumetric flack and add water for a final volume of 500 mL.
b. Add 1 mL of the solution from a to a 100 mL volumetric flask and make to a final volume of 100 mL.