Question

what is mole concept calculate the number of molecules in 45g of water

Answer 1

Mole Concept:
The mole is the unit of measurement in the International System of Units (SI) to measure the amount of substance. It can be defined as a number which represents 6.023x10²³ particles of same matter. When dealing with the particles of size of atoms and molecules, it became very difficult to do the calculations as they are present in very large numbers. So to make these calculations simpler, concept of mole was introduced.

Now we calculate the number of molecules in 45 g of water.
Mass of water = 45 g
Molecular mass of oxygen = 16 g
Molecular mass of hydrogen = 2 g
So,
Molecular mass of water = 16 + 2 = 18 g
Number of molecules on 45g of water = ?
Since,
Number of moles of water = Mass of water / Molecular mass of water
Number of moles of water = 45 / 18
Number of moles of water = 2.5 moles
which is the required answer.
Hope it helps. Thank