Question

What is the the molarity of pure water ?

Answer 1

We know that molarity=mol/L

The molar mass of water is roughly 18 g/mol. The density of water is roughly 1 g/mL. Since there are 1000 mL in a litre, there are 1000 grams in a litre of water.

# mol=(mass)/(molar mass)=(1000 g)/(18 g/mol)=55.56 mol water

Plugging back into the molarity formula, we get: M=(55.56 mol)/1 L=55.56 M

It is important to note that this value will change with temperature.