When making a 500 mL solution of 20% Dextrose from a 70% solution, how much of the 70% solution do you need?

To determine how much of the 70% dextrose solution is needed to create 500 mL of a 20% dextrose solution, it's essential to understand the concept of dilutions and concentrations.

First, calculate the total amount of dextrose required in the final 500 mL solution. Since the desired concentration is 20%, this means that 20% of 500 mL must be dextrose.

Calculating that gives us:

20% of 500 mL = 0.20 × 500 mL = 100 mL of dextrose.

Next, since the 70% solution contains 70 g of dextrose per 100 mL of solution, we can set up an equation to find out how much of the 70% solution we need to obtain 100 mL of dextrose.

Let x represent the volume of the 70% solution needed:

0.70x = 100 mL (This indicates that 70% of the volume x will provide the required 100 mL of pure dextrose).

To find x:

x = 100 mL / 0.70

x = 142.86 mL, which