Question

how many molecules are in 45.0 g of water

Answer 1

1.5055*10²³

Given mass = 45g
Molar mass of H2O = 2+16 = 18g

Moles = Given mass/Molar mass
= 45/18 = 2.5moles

No of molecule in 1 mole = 6.022*10²³
No of molecue in 2.5 mole = 2.5*6.022*10²³
= 1.5055*10²³