# Question #b7de9

##### 1 Answer

There are approximately

#### Explanation:

This depends on the density of water, which depends on the temperature and pressure. Let's assume that the density is

This is technically only true at

The formula for density of any substance is:

Rearrange this to solve for mass:

Now we need the number of particles, which chemists measure in moles. To find the number of moles, we need the mass and the molar mass. The molar mass is given by the sum of the individual molar masses of the constituent atoms in the molecule. In this case we have two hydrogens and one oxygen:

The Avogadro constant is the number of particles in one mole:

The number of moles multiplied by the Avogadro constant will tell you how many molecules there are:

Another way of doing this would be to use the molar volume of water.