To calculate the number of moles of H2O in 75.0g, we can use the formula:

Moles = Mass / Molar Mass

Substituting the given values, we get:

Moles = 75.0g / 18.01528 g/mol

Moles ≈ 4.164 moles

Therefore, there are approximately 4.164 moles of H2O in 75.0g of H2O.