Question

How will you convert $1.51 \times {10^{15}}$ atoms Si to mol Si?

Answer 1

To convert the number of atoms into number of moles, one should know about the following terms: Avagadro’s number, moles. 1 mole of any substance contains $6.022 \times {10^{23}}$number of atoms.

Complete step by step answer:
Here in this question it is given that the number of atoms of silicon present is $1.51 \times {10^{15}}$atoms.
We need to convert the number of atoms of silicon into the number of moles.
The mole is denoted by the symbol “mol” is the unit used for the measurement for the amount of substance in the International system of units (SI).
In the field of chemistry, the mole is defined as the amount of the substance which exactly contains the same quantity of $6.022 \times {10^{23}}$ number of entities which can be atoms, molecules or ions.
The number $6.022 \times {10^{23}}$ is known as the Avagadro’s constant. The Avagadro’s number is denoted by the symbol ${N_A}$.
The elementary entities which are represented in the moles can be atoms, molecules, polyatomic or monatomic ions, or other particles such as electrons.
The mole can be explained by taking the example where the sample of pure carbon-12 will possess the same mass exactly 12 grams which will contain $6.022 \times {10^{23}}$ number of carbon-12 atoms.
To convert the $1.51 \times {10^{15}}$ atoms Si to mol Si, divide the number of atoms by the Avagadro’s number.
$\Rightarrow \dfrac{{1.51 \times {{10}^{15}}}}{{6.022 \times {{10}^{23}}}}$
$\Rightarrow 0.252 \times {10^{ - 8}}$
$\Rightarrow 2.52 \times {10^{ - 9}}mol$

In other words it can be said that $1.51 \times {10^{15}}$Si atom contains $2.52 \times {10^{ - 9}}$ number of moles..

Note: The number of moles of the substance in a pure sample is given by the formula as shown below.
$n = \dfrac{N}{{{N_A}}}$
Where,
n is the number of moles.
N is the total number of elementary units
${N_A}$ is Avogadro's number.