Question

How many atoms of hydrogen and oxygen are present in 0.15 moles of water.

Answer 1

We know that

• 1 mole of water$=6.022\times {10}^{23}$molecules of water.
• 0.15 mole of water$=6.022\times {10}^{23}\times 0.15$

$=9.03\times {10}^{22}$molecules of water.

• Now 1 molecule of ${\mathrm{H}}_2\mathrm{O}$ contains two hydrogen atoms and 1 oxygen atom

Part 1: Calculating the number of $\mathrm{H}$ atoms present in ${\mathrm{H}}_2\mathrm{O}$

The number of $2\mathrm{H}$ atoms present in $9.03\times {10}^{22}$ molecules of ${\mathrm{H}}_2\mathrm{O}$

So, the number of the hydrogen atoms in water molecule$=2\times 9.03\times {10}^{22}=1.806\times {10}^{23}$atoms

Part 2: Calculating the number of $\mathrm{O}$ atoms present in ${\mathrm{H}}_2\mathrm{O}$

The number of 1 oxygen atom in $9.03\times {10}^{22}$molecules of ${\mathrm{H}}_2\mathrm{O}$

So, the number of the Oxygen atom in water molecule=$=9.03\times {10}^{22}$atoms