Question 9.11: Calculating Molarity What is the molarity (M) of 60.0 g of N......

STEP 1 State the given and needed quantities.

To calculate the moles of NaOH, we need to write the equality and conversion factors for the molar mass of NaOH. Then the moles in 60.0 g of NaOH can be determined.

\begin{aligned} & \begin{aligned} & 1\text{ mole} \text { of NaOH}=40.00\ g \text { of NaOH} \\ & \begin{aligned} \frac{40.00\text{ g NaOH} }{1\text{ mole NaOH} } & \text { and } \frac{1\text{ mole NaOH} }{40.00\text{ g NaOH} } \end{aligned} \\ & \text { moles of } NaOH =60.0\cancel{\ g\ NaOH} \times \frac{1\text{ mole NaOH} }{40.00\cancel{ g~ NaOH} } \\ &=1.50\text{ moles} \text { of } NaOH \end{aligned} \\ & \text { volume of solution }=0.250\text{ L} \text { of } NaOH \text { solution } \end{aligned}

STEP 2 Write the concentration expression.

\text { Molarity }( M )=\frac{\text { moles of solute }}{\text { liters of solution }}

STEP 3 Substitute solute and solution quantities into the expression and calculate.

M =\underset{\text{Three SFs}}{\overset{\text{Three SFs}}{\frac{1.50 \text { moles } NaOH }{0.250\ L \text { solution }}}}=\underset{\text{Exact}}{\overset{\text{Three SFs}}{\frac{6.00\text{ moles NaOH} }{1\ L \text { solution }}}}=\underset{\text{Three SFs}}{6.00\ M\ NaOH \text { solution }}