If you need to dilute a 20% solution to make a 28% solution, how many ml of the 30% stock solution will you need?

To determine how much of the 30% stock solution is needed to create a 28% solution, it's essential to understand the concept of dilution and concentration.

In this problem, you are mixing two different concentrations of solutions. You want the final mixture to have a concentration that falls between the two original concentrations of the stock solution and the desired solution.

When calculating how many milliliters of the 30% solution you need, you will typically use the formula for dilution or the concept of mass balance. The aim is to reach the desired concentration of 28% by effectively balancing the amounts of stock solution and any water or other solutions being added.

In this scenario, if you already have a 20% solution and need to end up with 28%, it is crucial to recognize that increasing the concentration from 20% to 28% will require you to adjust the amounts of the more concentrated stock solution (30%) mixed with the less concentrated one.

Given that the desired solution concentration is higher than that of your starting solution (20%), you would be looking at combining the 30% stock solution with the 20% solution in such a way as to achieve the specific volume required for the final concentration.

When calculating, identifying the correct total