How many water molecules are in a 10.0g sample of water?

Answer 1

First you need the molar mass of water(H2O).

Given that oxygen is 16 g mole^-1 and hydrogen is 1 g mole^-1 the molar mass of water is 18 g mole^-1.

Next we need the number of moles of water that 10.0 g represents (N) which we get from

N=10.0 g / 18 g mole^-1

as one mole contains 6x10^23 molecules then

Nx6x10^23 is the number of molecules.

Answer 2

3.34x10^23