Question

A patient needs to be given exactly 500 ml of a 5.0% (w/v) intravenous glucose solution. the stock solution is 35% (w/v). how many milliliters of the stock solution are needed to prepare the fluid for the iv bag?

Answer 1

Answer is: 71.43 milliliters of the stock solution are needed.

V(solution of glucose) = 500 mL; voume of the solution.

ω(solution) = 5.0% ÷ 100%.

ω(solution) = 0.05.

ω(stock solution) = 35% ÷ 100%.

ω(stock solution) = 0.35.

Because weight of the glucose is the same in both solutions:

0.05 · 500 mL = 0.35 · V(stock solution).

V(stock solution) = 500 mL · 0.05 ÷ 0.35.

V(stock solution) = 71.43 mL.

Answer 2

In this question, the patient needs to be given exactly 500 ml of a 5.0%. The content of the glucose should be:
weight= volume * density* concentration
500ml * 1mg/ml *5%= 25mg.

The stock solution is 35%, then the amount needed in ml would be: 
weight= volume * density* concentration
25mg= volume * 1mg/ml *35%
volume= 25/35%= 500/7= 71.43ml