Question

How many oxygen atoms are present in $0.1$ moles of carbon dioxide?

Answer 1

We need a way to compare the numbers and relate them to the weights of the substances, which we can measure and observe. The solution is the concept of the mole, which is very important in quantitative chemistry. One must know what moles and mole concepts are.

Complete answer:
We can calculate oxygen atoms and the procedure is as followed:
One molecule of carbon dioxide has two oxygen atoms and one carbon atom.
$1$mole of carbon dioxide contains $2g$ atoms of oxygen
So, $0.1$ mole of carbon dioxide contains $2g \times 0.1 = 0.2g$ atoms of oxygen
So, number of oxygen atoms in $0.1$moles of carbon dioxide
=no. of moles x Avogadro’s number
$= 0.2 \times 6.22 \times {10^{23}}$
$= 1.0244 \times {10^{23}}atoms$
The molecular mass of $C{O_2}$
$= 1 \times {\text{atomicmass of carbon}} + 2 \times {\text{Atomic mass of oxygen}}$
$= \left( {12} \right) + \left( {2 \times 16} \right) = 12 + 32 = 44u$
Number of moles can be calculated as the given mass of any substance, atom or molecule divided by the molecular mass of any substance, atom or molecule. Avogadro's number, number of units in one mole of any substance (defined as its molecular weight in grams), equal to $6.022 \times {10^{23}}$. The units may be electrons, atoms, ions, or molecules, depending on the nature of the substance and the character of the reaction . One mole of a substance is equal to $6.022 \times {10^{23}}$ units of that substance (such as atoms, molecules, or ions). The number $6.022 \times {10^{23}}$ is known as Avogadro's number or Avogadro's constant.

Note:
We have to know that the molecular mass can be represented as the mass of a substance is the sum of atomic masses of all the atoms in a molecule of the substance. It is used for those substances whose constituent particles are molecules. The number $6.022 \times {10^{23}}$ is known as Avogadro's number.