# Question d2b20

Nov 15, 2016

$\text{2.91% m/v}$

#### Explanation:

Yes, weight by volume, $\text{w/v}$, and mass by volume, $\text{m/v}$, are often used interchangeably.

The important thing to remember when dealing with either one is that you're always working with mass, so even if you have weight by volume, you're still going to use mass, as opposed to weight.

So, a solution's mass by volume percent concentration is defined as the mass of solute present in $\text{100 mL}$ of solution.

This means that in order to find your solution's $\text{%m/v}$ concentration, all you need to do is figure out how many grams dextrose you get in $\text{100 mL}$ of solution.

To do that, use the known composition as a conversion factor

100 color(red)(cancel(color(black)("mL solution"))) * "8.00 g dextrose"/(275 color(red)(cancel(color(black)("mL solution")))) = "2.91 g dextrose"#

This means that the solution's mass by volume percent concentration will be

$\textcolor{\mathrm{da} r k g r e e n}{\underline{\textcolor{b l a c k}{\text{% m/v " = " 2.91% dextrose}}}}$

The answer is rounded to three sig figs.