Question

Calculate the molarity of pure water using its density to be 1000 kg $m^{-3}$

Answer 1

Density of the Water = 1000 $kg/m^3$

We know,

1 liter of water = 1 kg.

( Since, Density is 1000 $kg/m^3$

Thus, 1000 ml of water = 1 kg.

(Since, 1 liter = 1000 ml)

Now, Mass of Water = 1 kg.

= 1000 g.

The molecular mass of the water molecules = 18 grams.

Using the formula,

No.of moles $=\frac{mass}{molarmass}$

$=\frac{1000}{18}$

$=55.56moles$

For the Molarity,

Using the Formula,

Molarity $=\frac{Numberofmoles}{volumeinml}\times 1000$

$=\frac{55.56}{1000}\times 1000$

$=55.56M$