Question

Calculate the number of oxygen atoms in 88g $C{O}_{2}$. What would be the mass of $CO$ having the same number of oxygen atoms?

Answer 1

Hint: Mole concept is an important step that is used to calculate the amount of a substance in a compound or in a reaction. It establishes a relation between the weight, no. of moles and no. of molecules of a compound.
It is given as, $No.\quad of\quad moles\quad =\quad \cfrac { Weight\quad of\quad compound }{ Molecular\quad weight\quad of\quad compound } $

Complete step by step answer:
The mole concept is an easy way of expressing the amount of substance. It can be broken down into two parts: the numerical magnitude and the units in which the numerical magnitude can be expressed.
We know that in 1 mole of any compound there are $6.022 \times {10}^{23}$ atoms of a particular element. Here, $6.022 \times {10}^{23}$ is the Avogadro number, N.
One molecule of $C{O}_{2}$ contains 2 atoms of oxygen.
So, no. of oxygen atoms in 44 g of $C{O}_{2}$ contains is $2 \times 6.022 \times {10}^{23}$ atoms.
Therefore, no. of oxygen atoms in 88 g of $C{O}_{2}$ contains is $2 \times 2 \times 6.022 \times {10}^{23}$ atoms.
Hence, the no. of oxygen atoms present in 88 g of $C{O}_{2}$ is $2.41 \times {10}^{24}$ atoms.
Now, we know that one molecule of CO contains one atom of oxygen.
Thus, mass of CO that contains $2.41 \times {10}^{24}$ atoms of oxygen can be written as:

$Mass \quad of \quad CO = \dfrac { Molecular\quad mass\quad of\quad CO }{ Avogadro\quad number } \quad \times \quad No.\quad of\quad atoms\quad of\quad oxygen\quad$

The molecular mass of CO is 28 g/mol. Substituting all the values in the above equation, we get

$Mass\quad of\quad CO\quad =\quad \dfrac { 28 }{ 6.022\quad \times \quad { 10 }^{ 23 } } \quad \times \quad 2.41\quad \times \quad { 10 }^{ 23 }\quad$
$\implies Mass\quad of\quad CO\quad =\quad 112g$

Therefore the mass of CO that contains $2.41 \times {10}^{24}$ atoms of oxygen is 112g.

Note: While solving these types of questions, do take care of the respective units of the substances. Make sure you know the difference between a mole, a molecule, an atom and a compound.
An atom is the smallest unit of ordinary matter. A compound is composed of two or separate elements. A molecule is also composed of two or more separate elements but it can be homonuclear as well as heteronuclear. A mole of a substance is defined as exactly $6.02214076 \times {10}^{23}$ particles and the particles can be molecules, atoms, compounds, ions or electrons.