Final answer:
To calculate the mass in grams of a single molecule of water, divide the molar mass of water (18.015 g/mol) by Avogadro's number (6.022 × 1023 molecules/mol), resulting in approximately 2.99 × 10-23 grams per molecule.
Step-by-step explanation:
To find the mass of a single molecule of water (H2O) in grams, we must use Avogadro's number and the molar mass of water. The molar mass of water, based on the atomic masses of hydrogen and oxygen, is approximately 18.015 g/mol. Since one mole of any substance contains approximately 6.022 × 1023 molecules (Avogadro's number), we can determine the mass of one molecule by dividing the molar mass by Avogadro's number.
The calculation is as follows:
- Molar mass of H2O = 18.015 g/mol
- Avogadro's number = 6.022 × 1023 molecules/mol
- Mass of a single water molecule = 18.015 g/mol ÷ 6.022 × 1023 molecules/mol
After performing the division, the mass of a single molecule of water is approximately 2.99 × 10-23 grams.