Question

What is the molarity of a 250.0 ml aqueous solution of sodium hydroxide that contains 15.5 grams of solute?

Answer 1

Answer:

Molarity of solution is 1.5501

Explanation:

Given data:

Molarity of NaOH = ?

Volume of solution = 250 ml

Mass of solute = 15.5 grams

Solution:

Formula:

Molarity = Mass of solute/Molar mass of solute * 1/volume of solution in liters.

First convert volume into Liters = 250/1000 =0.25 L

Now put the values in formula:

Molarity of NaOH = 15.5/39.997 * 1/0.25

                              = 1.5501

                                         Molarity of NaOH      =  1.55011

Answer 2

The molar concentration of the solution is 1.55 mol/L.

1. Convert grams to moles.

$\text{Moles of NaOH} = 15.5 \text{g NaOH} \times \frac{\text{1 mol NaOH}}{\text{40.00 g NaOH}} = \text{0.3875 mol NaOH}$

2. Convert millilitres to litres

$V = 250.0 \text{mL} \times \frac{\text{1 L}}{\text{1000 mL}} = \text{0.2500 L}$

3. Calculate the molar concentration (c)

$c = \frac{\text{moles}}{\text{litres}} = \frac{\text{0.2875 mol}}{\text{0.2500 L}} = \textbf{1.55 mol/L}$