Question

Explain how to calculate the number of atoms of a certain element in a given mass of a compound?

Answer 1

The amount of a substance can be expressed in different units like number of atoms, grams or moles. Each unit is different but can be converted from one to another. To convert from one to another we need the molar mass, weight in grams or number of atoms and Avogadro’s number.

Complete answer:
Compounds are the mixture of a particular element with more than two atoms. Element is the purest form and contains only atoms of a particular element.
The amount of a compound can be expressed in different forms like number of atoms, grams or moles. The mole is the unit used to express the amount of substance.
But, $1mole = 6.023 \times {10^{23}}$ particles. These particles may be atoms or molecules or ions. This number is called Avogadro's number.
To convert the number of atoms of a certain element in a given mass of a compound, we need molar mass of that element, weight or amount of the substance and Avogadro’s number.
For example, let $x$ be the given weight of a substance in grams, then that particular $x$ has molar mass in the atomic mass unit in the periodic table. Then the weight will have to be divided by molar mass and the result has to be multiplied by Avogadro’s number. Thus, the weight in grams was converted into the number of atoms.

Note:
The molar mass of the element can be clearly determined from the periodic table and has to be taken in an atomic mass unit. A Simple atomic mass unit will be amu. The weight must be divided with molar mass and multiplied by Avogadro’s number only.