Question

Calculate the number of molecules of $ C{H_4} $ in $ 48g $ $ C{H_4} $ ?

Answer 1

Hint: Avogadro's number or Avogadro's constant is the number of units in one mole of any substance. Its value is $ 6.022 \times {10^{23}} $ . Depending on the reaction and the nature of the substance, the units could be electrons, ions, atoms, or molecules.
 $ Number{\text{ of moles = }}\dfrac{{Mass}}{{Molar{\text{ mass}}}} $

Complete Step By Step Answer:
Given:
Mass of $ C{H_4} $ $ = 48g $
To find: Number of molecules
We know that the molar mass of $ C{H_4} $ is $ 16 $ .
In order to find number of molecules we first need to calculate number of moles,
Using the formula,
 $ Number{\text{ of moles = }}\dfrac{{Mass}}{{Molar{\text{ mass}}}} $
Number of moles $ = \dfrac{{48}}{{16}} $
Number of moles $ = 3 $
Number of molecules = Number of moles $ \times $ Avogadro’s number
Number of molecules = $ 3 \times 6.022 \times {10^{23}} $
Number of molecules $ \Rightarrow 1.806 \times {10^{24}} $

Additional Information:
Substances are measured at the atomic level in terms of atomic mass units. The atomic mass unit is defined as one-twelfth of one carbon atom's mass.
Hydrogen, for example, has an atomic mass unit of $ 1.00794{\text{ }}amu $ . It is now impossible to calculate the ability of a single particle (atom, electron, molecule) to carry out a reaction.
Chemists devised a method of linking the atomic mass unit to the gramme.
 $ 1.66{\text{ }} \times {\text{ }}{10^{ - 24}}{\text{ }}gram{\text{ }} = {\text{ }}1{\text{ }}amu $
We can use this to convert between gram measurements and the atomic mass unit's invisible unit of measurement. As a result, Avogadro's number has this significance.

Note:
Divide the charge of a mole of electrons by the charge of a single electron, which is equal to $ 6.022 \times {10^{23}} $ particles per mole, to get Avogadro's number. The molecular mass of an element is equal to the sum of its constituent elements' atomic masses. The atomic mass units are also used to denote this amount.