How much sterile water is needed to create 500 mL of 20% Dextrose when starting with a 1000 mL bag of 70% Dextrose?

To determine how much sterile water is needed to create a 500 mL solution of 20% Dextrose from a 1000 mL bag of 70% Dextrose, it's essential to consider the dilution process involved in making the solution.

First, calculate the total amount of Dextrose required for the final 500 mL solution at 20% concentration. Since 20% Dextrose means there are 20 grams of Dextrose in 100 mL, in 500 mL, this translates to:

[

500 , \text{mL} \times 0.20 = 100 , \text{grams of Dextrose}

]

Next, calculate how much of the 70% Dextrose solution is needed to achieve this amount. The 70% Dextrose solution contains 70 grams of Dextrose per 100 mL. To find out how many mL are needed to get 100 grams of Dextrose:

[

\text{Concentration (g/mL)} = \frac{70 , \text{g}}{100 , \text{mL}} = 0.7 , \text{g