VSA : Give the number of molecules present in 1.8 g water

Question 3

Give the number of molecules present in 1.8 g water. [Ans. 3.011× 10²²]

Answer

Molar mass of water (H₂O) is = 18

So, the number of moles of water in 1.8 g of water is:

moles = mass/molar mass

= 1.8 / 18

= 0.1 mol

Next, we can use Avogadro’s number to convert from moles to the number of molecules:

number of molecules = moles × Avogadro’s number

= 0.1 × 6.022 × 10²³

= 6.022 × 10²² molecules

Therefore, there are approximately 6.022 × 10²² water molecules present in 1.8 g of water.