To determine the number of molecules of water (H2O) in a given mass, you can use Avogadro's number and the molar mass of water.
The molar mass of water (H2O) is calculated as follows: 2(atomic mass of hydrogen) + 1(atomic mass of oxygen) = 2(1.008 g/mol) + 1(16.00 g/mol) = 2.016 g/mol + 16.00 g/mol = 18.016 g/mol
Now, we can calculate the number of moles in 54 g of water using the molar mass: Number of moles = Mass / Molar mass = 54 g / 18.016 g/mol = 2.9979 moles (rounded to four decimal places)
Since one mole of water contains Avogadro's number of molecules (approximately 6.022 × 10^23), we can calculate the number of water molecules by multiplying the number of moles by Avogadro's number: Number of water molecules = Number of moles × Avogadro's number = 2.9979 moles × 6.022 × 10^23 molecules/mol ≈ 1.806 × 10^24 molecules
Therefore, there are approximately 1.806 × 10^24 molecules of water in 54 g of H2O.