Question

Calculate the molarity of a solution that is made of 75 g NaCl in 1.0 L of water

Answer 1

Molarity = 1.28 mol/L

Step-by-step explanation

Given:

Mass of NaCl = 75 g

Volume of water = 1.0 L

What to find:

The molarity of the solution.

Step-by-step solution:

The molarity of the solution can be calculated using the molarity formula given below:

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

However, you need to convert the mass of NaCl given to moles using the mole formula; Mass divided by molar mass.

The molar mass of NaCl = 58.44 g/mol

`Mole=(Mass)/(Molarmass)=\frac{75\text{ }g}{58.44\text{ }g\text{/}mol}=1.283367556\text{ }mol`

Now, the molarity is

`Molarity=\frac{1.283367556\text{ }mol}{1.0\text{ }L}=1.283367556\text{ }mol\text{/}L\approx1.28\text{ }mol\text{/}L`

Hence, the molarity of the solution is 1.28 mol/L