What volume of 0.10 M NaOHNaOH can be prepared from 250 mL of 0.30 M NaOHNaOH?

1 Answer
Jul 29, 2016

"750 mL"750 mL

Explanation:

The thing to notice here is that the initial solution is 33 times more concentrated than the target solution, since

(0.30 color(red)(cancel(color(black)("M"))))/(0.10color(red)(cancel(color(black)("M")))) = 3

This tells you that the volume of the target solution must be 3 times greater than the volume of the initial solution.

That is the case because when you dilute a solution, you decrease its concentration by increasing its volume while keeping the number of moles of solute constant.

http://acidsandbasesfordummieschem.weebly.com/molarity.htmlhttp://acidsandbasesfordummieschem.weebly.com/molarity.html

This implies that when the concentration of a solution decreases by a factor, which is usually called dilution factor, "DF", upon dilution, the volume of the diluted solution increases by the same factor "DF".

color(blue)(|bar(ul(color(white)(a/a)"DF" = V_"final"/V_"initial" = c_"initial"/c_"final"color(white)(a/a)|)))

You thus have

V_"final" = 3 xx "250 mL" = color(green)(|bar(ul(color(white)(a/a)color(black)("750 mL")color(white)(a/a)|)))

The answer is rounded to two sig figs.

So, you can decrease the concentration of "250 mL" of sodium hydroxide solution from "0.30 M" to "0.10 M" by adding enough water to get its final volume to "750 mL".