# What mass of NaOH is contained in 250.0 mL of a 0.400 M sodium hydroxide solution?

May 23, 2016

$\text{Approx. 4 g of NaOH.}$

#### Explanation:

$\text{Concentration}$ $=$ $\text{Moles"/"Volume of solution}$

$\text{Number of moles}$ $=$ $\text{Volume"xx"concentration } =$

$0.250 \cdot L \times 0.400 \cdot m o l \cdot {L}^{-} 1$

$=$ $0.100 \cdot m o l$

$\text{Mass of sodium hydroxide}$ $=$ $0.100 \cdot m o l \times 40.0 \cdot g \cdot m o {l}^{-} 1$

=??*g

May 23, 2016

3.998 grams NaOH

#### Explanation:

The Molarity of a solution is determined by the comparison of the moles of the solute compared to the volume of the solution in liters.

The equation of the formula is $M = \frac{m o l}{L}$

In order to find the mass we first need to solve for the moles.

$m o l = \frac{M}{L}$

M = 0.400
moles = ?
L = 250.0 mL or 0.25 L

0.400 M (0.25 L) = (? mol)

$0.100 m o l o f N a O H$

Now we can calculate the grams be converting moles to grams.

$N a = 22.98 g$
$O = 15.99 g$
$H = 1.01 g$

$N a O H = 39.98 g$

0.100 cancel(mol NaOH) x (39.98 g NaOH)/( 1 cancel(molNaOH)

3.998 grams NaOH