Question

How many molecules are present in 72g of water

Answer 1

Answer:

4x6.022x10^23 molecules

Explanation:

no of moles= given mass/ molecular mass

                   = 72/18

                   =4 moles

no of molecules= moles x avangadro no.

                          = 4x6.022x10^23 moles

Answer 2

Given: 72 grams of water.

To find: Here we have to find the number of moles.

Solution:

To determine the number of moles of 72g of water we have to follow the below steps-

The chemical formula of water is $H_2O$

We know that the atomic number of H is 1 and the atomic number of oxygen is 16.

Thus the molecular weight of water is 1×2+16=18 gram.

Thus 18 grams of water have $6.023×10^{23}$ number of molecules.

So, 72 grams of water have $6.023×10^{23}×72/18=24.092×10^{23}$ number of molecules.

So, 72 grams of water have $24.092×10^{23}$ number of molecules.