Question

9. Calculate the molarity of a 400.0 mL solution that contains 41.5 g of NaCl.

Answer 1

1.775 M

Step-by-step explanation

Given:

Volume of solution, V = 400.0 mL

Mass of NaCl = 45.5 g

What to find:

The molarity of the solution.

Step-by-step solution:

Step 1: Convert the volume from mL to L.

This can be done by dividing the volume in mL by 1000.

V = 400.0 mL = (400.0/1000) = 0.4L

Step 2: Convert the mass of NaCl to moles.

The mass can be converted to moles using the mole formula below:

`\begin{gathered} Moles=\frac{Mass}{Molar\text{ }mass} \\ \end{gathered}`

From the periodic table, the molar mass is determined to be = 58.44 g/mol

Putting mass = 41.5 g and molar mass = 58.44 g/mol into the formula, we have:

`Moles=\frac{41.5g}{58.44g\text{/}mol}=0.7101\text{ }mol`

Step 3: Calculate the molarity of the solution using the molarity formula.

Molarity formula is given by:

`Molarity=\frac{Moles}{Volume\text{ }in\text{ }L}`

Moles= 0.7101 mol and V = 0.4 L

Therefore,

`Molarity=(0.7101mol)/(0.4L)=1.775\text{ }M`

The molarity of a 400.0 mL solution that contains 41.5 g of NaCl = 1.775 M.