Question

How many mL of 0.350 M solution contains 0.200 mol of solute?

Answer 1

`"571 mL"`

Explanation:

The thing to remember about molarity is that its purpose is to tell you how many moles of solute you get in one liter of solution.

This means that every time you're looking at the molarity of a solution, you're actually looking at the number of moles of solute present in `"1 L"` of solution.

In this case, a molarity of `"0.350 M"` means that `"1 L"` of this solution contains `0.350` moles of solute.

The immediate conclusion here is that you can use the molarity of a solution as a conversion factor to help you convert between the number of moles of solute and the volume of the solution and vice versa.

You will thus have

`0.200 color(red)(cancel(color(black)("moles solute"))) * overbrace("1 L solution"/(0.350 color(red)(cancel(color(black)("moles solute")))))^(color(blue)("= 0.350 M")) = "0.571 L solution"`

Now all you have to do is convert this to milliliters

`0.571 color(red)(cancel(color(black)("L"))) * (10^3"mL")/(1color(red)(cancel(color(black)("L")))) = color(green)(bar(ul(|color(white)(a/a)color(black)("571 mL")color(white)(a/a)|)))`

The answer is rounded to three sig figs.