Calculate the number of H2O molecules in a human body of mass 50.6 kg. Assume that, on average, water makes up 62% of the mass of a human body. (Use 1.0 u for the atomic mass of hydrogen, and 16.0 u for the atomic mass of oxygen.)

To calculate the number of H2O molecules in a human body, we need to follow these steps:

1. Calculate the mass of water in the human body: Multiply the mass of the human body (50.6 kg) by the percentage of water in the body (62%).

Mass of water = 50.6 kg * 0.62 = 31.372 kg

2. Calculate the number of moles of water: Divide the mass of water by the molar mass of water.

Molar mass of water (H2O) = (2 * 1.0 u for hydrogen) + (1 * 16.0 u for oxygen) = 18.0 u

Number of moles of water = Mass of water / Molar mass of water
= 31.372 kg / 18.0 u

3. Calculate the number of water molecules: Use Avogadro's number (6.022 x 10^23) to convert moles into molecules.

Number of water molecules = Number of moles of water * Avogadro's number
= (31.372 kg / 18.0 u) * 6.022 x 10^23

Now, plug in the values to get the final answer.