Final answer:
To find the mass of 3.71 × 10³³ molecules of water (H₂O), you calculate the number of moles and then multiply by the molecular mass of water (18 g/mol). The result is approximately 11.088 grams of water.
Step-by-step explanation:
To calculate the mass of water (H₂O) from the number of molecules, we use the concept of the mole, which is the unit used in chemistry to represent Avogadro's number, 6.022 × 10²³, of something. The molecular mass of water is 18 g/mol, meaning one mole of water weighs 18 grams. You have 3.71 × 10³³ molecules of water, which is equivalent to 3.71 × 10³³ / 6.022 × 10²³ moles. To find the mass in grams, we multiply the moles of water by the molar mass of water (18 g/mol).
First, calculate the number of moles:
3.71 × 10³³ molecules ÷ 6.022 × 10²³ molecules/mole = 0.616 moles of water (approximately).
Next, calculate the mass:
0.616 moles × 18 g/mole = 11.088 g of water.
Therefore, you have approximately 11.088 grams of water.