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The goal of this question is to determine the number of atoms in $1.75\,mol$ $CHCl_3$.

An atom is the smallest unit in which matter can be divided without releasing electrically charged particles possessing distinctive chemical element properties. A significant proportion of the atom is an empty space. The rest of the structure is made up of a positively charged nucleus of protons and neutrons surrounded by negatively charged electrons.

Atoms can combine with each other in a variety of different ways. Different molecules can be formed by combining the same atoms in different proportions. A molecule is two or more atoms that are linked together by chemical bonds that form the smallest unit of a substance, preserving its composition and properties. Molecules are identified by the element symbol and a subscript indicating the number of atoms.

A mole is essentially a measurement unit. One mole is equal to Avogadro’s number of particles, which equals to exactly $6.02214076\times 10^{23}$.

## Expert Answer

To find the number of atoms in any number of moles, multiply the number of moles by Avogadro’s constant. This yields the number of molecules, which is then multiplied by the number of atoms, yielding one molecule.

Here, $1$ mole of $CHCl_3$ will have $1$ mole of $C$, $1$ mole of $H$ and $3$ moles of $Cl$.

And so $1.755$ mol $CHCl_3$ will contain:

$1.75\times 5\times 6.022\times 10^{23}$

$=5.2692\times 10^{24}$ atoms.

## Example 1

Determine the number of moles of $H_2$ in $20\,g$ of $H_2$.

Given mass of $H_2$ is $20\,g$

and molar mass of $H_2$ is $20\,g$.

Since the number of moles in a substance $=$ Given mass of the substance / Molar mass of the substance

Therefore, number of moles $=\dfrac{20}{2}=10$ moles.

## Example 2

Determine how many hydrogen atoms are in three moles of $H_2$.

Since one molecule of $H_2$ is equal to two atoms of hydrogen,

And one mole of $H_2$ is equal to two mole hydrogen atoms.

So, $3$ moles of $H_2=3(2)=6$ moles hydrogen atoms.

$=6\times 6.022\times 10^{23}=36.132\times 10^{23}$ hydrogen atoms.

## Example 3

Determine the number of moles and atoms of $H$ and $S$ in a $5$ mole of $H_2S$.

$1$ mole of $H_2S$ have $2$ moles of $H$ and $1$ mole of $S$.

So, $5$ moles of $H_2S$ will contain:

$10$ moles of $H$ and are equal to:

$10\times 6.022\times 10^{23}=6.022\times 10^{24}\,\,H$ atoms

and $5$ moles of $S$ are equal to:

$5\times 6.022\times 10^{23}=3.011\times 10^{24}\,\,S$ atoms