How many water molecules are in a runner's body?

How many water molecules are there in a runner's body?

A runner weighs 507 N and 71% of this weight is water. How many water molecules (H2O) are there?

Answer:

(a) There are approximately 20 moles of water in the runner's body, and (b) there are approximately 1.204 x 10^25 water molecules (H2O) in the runner's body.

To calculate the number of water molecules in a runner's body, we first need to determine the mass of water in the runner's body. Given that the runner weighs 507 N and 71% of this weight is water, we can follow these steps:

Calculating the mass of water:

Mass of water = (Percentage of water/100) * Weight of the runner

Mass of water = (71/100) * 507 N = 359.97 N

Next, we need to convert the mass of water into moles using the molar mass of water, approximately 18 g/mol.

Calculating the number of moles of water:

Number of moles of water = Mass of water / Molar mass of water

Number of moles of water = 359.97 N / 18 g/mol ≈ 20 moles

Finally, to find the number of water molecules (H2O), we use Avogadro's number, which is approximately 6.022 x 10^23 molecules/mol.

Number of water molecules = Number of moles of water * Avogadro's number

Number of water molecules = 20 moles * 6.022 x 10^23 molecules/mol ≈ 1.204 x 10^25 water molecules

Therefore, there are approximately 20 moles of water and 1.204 x 10^25 water molecules (H2O) in the runner's body. Stay hydrated, folks!