What is the mass of a rain drop if the drop contains 3.35 * 10 ^ 14 water molecules

In order to calculate the mass of a given drop of water, you need to push off from the mass or amount of a substance with a known number of molecules. We will use a constant for the solution – Avogadro’s number 6.02 * 10 ^ 23. This is how many water molecules are contained in 1 mole of a substance.

One mole of water has a mass of 18 g. This means that 18 g of water contains 6.02 * 10 ^ 23 molecules. Let’s find out what mass 3.35 * 10 ^ 14 water molecules will have.

Let’s make the proportion:

6.02 * 10 ^ 23 water molecules weigh 18 g, then

3.35 * 10 ^ 14 water molecules weighing X g.

X = (3.35 * 10 ^ 14 * 18) / (6.02 * 10 ^ 23) = 9.93 * 10 ^ -9 g of water.

Answer: the mass of water is 9.93 * 10 ^ -9 g.