Mole Concept And Molar Masses

We are given that: - 1 mL of water contains 25 drops - The density of water = 1 g/mL - The molecular weight of water (H₂O) = 18 g/mol - is Avogadro's number

Step 1: Calculate the mass of 1 drop of water. The mass of 1 mL of water = 1 g, and there are 25 drops in 1 mL, so the mass of 1 drop of water is:
Mass of 1 drop = g

Step 2: Calculate the number of moles in 1 drop of water. The number of moles of water in 1 drop is:
mol

Step 3: Calculate the number of molecules in 1 drop of water. The number of molecules in 1 drop is:
This simplifies to:
Finally, we get:
Answer: