Question

How many atoms of oxygen and hydrogen are present in 0.15 mole of water?

Answer 1

2×0.15×avagadro number for hydrogen 0.15×avagadro number for Oxygen

Answer 2

Answer : The number of oxygen and hydrogen atoms are, $0.9\times 10^{23}$ and $1.8\times 10^{23}$ respectively.

Solution : Given,

Moles of water, $H_2O$ = 0.15 mole

As we know that,

1 mole contains $6.022\times 10^{23}$ number of atoms

In water molecule, there are two number of hydrogen atoms and 1 number of oxygen atom.

Now we have to calculate the number of atoms of hydrogen.

As, 1 mole of water contains $2\times (6.022\times 10^{23})$ number of atoms of hydrogen

So, 0.15 mole of water contains $0.15\times 2\times (6.022\times 10^{23})=1.8\times 10^{23}$ number of atoms of hydrogen

Now we have to calculate the number of atoms of oxygen.

As, 1 mole of water contains $1\times (6.022\times 10^{23})$ number of atoms of hydrogen

So, 0.15 mole of water contains $0.15\times 1\times (6.022\times 10^{23})=0.9\times 10^{23}$ number of atoms of hydrogen

Therefore, the number of oxygen and hydrogen atoms are, $0.9\times 10^{23}$ and $1.8\times 10^{23}$ respectively.