Final answer:
There are approximately 4.16 moles of water present in 75.0 g of H2O, which is closest to 4 moles (Option C). This is determined by dividing the mass of water by the molar mass of H2O, which is 18.015 g/mol.
Step-by-step explanation:
To determine how many moles of water (H2O) are present in 75.0 g H2O, we utilize the molar mass of water as a conversion factor from mass to moles.
The molar mass of water is calculated by adding the atomic masses of hydrogen and oxygen, which are approximately 1.0079 g/mol for each hydrogen atom and 15.999 g/mol for one oxygen atom. Therefore:
- Molar mass of H2O = (1.0079 * 2) + 15.999 = 18.015 g/mol.
To convert the mass of water to moles, we use the formula:
Moles of H2O = mass of H2O / molar mass of H2O
Moles of H2O = 75.0 g / 18.015 g/mol
Moles of H2O ≈ 4.16, which is closest to 4 moles (Option C).