# Question 310dc

Apr 19, 2015

All this problem requires is that you know the mathematical definition of molarity (M):
$M$=number of moles (n) $\div$ Volume (in Liters)

$M = \frac{n}{V}$

This question tells you the value of both M & n, all we must do is solve for V.

if $M = \frac{n}{V}$ then $M \cdot V = n$ and finally $V = \frac{n}{M}$

We can check if this equation works by using only units and seeing if they cancel correctly.

Liter=(mol)/((mol)/(Liter)#$\to$$L i t e r = m o l \cdot \frac{L i t e r}{m o l}$

Notice: the mol cancel out leaving us with Liters, so the equation must work.

Now let's plug in the given numbers:

$\frac{3.00 m o l}{12 M} = 0.25 L$

$0.25 L \cdot \frac{1000 m L}{1 L} = 250 m L$ volume required (in mL) for a solution of 3.00 mole HCl to have a molarity of 12