Question

What is the number of moles of aluminum in 54 g of Al?

Answer 1

Hint: Number of moles is the measure of the atoms of any compound. 1 mole of any compound contains an Avogadro number of atoms or particles that is $6.022\times {{10}^{23}}$ atoms. These atoms are considered as 1 mole, which is also the molar mass of any atom, means in the molar mass of any atom, there will be $6.022\times {{10}^{23}}$ particles.
Formula used:
Number of moles = $\dfrac{given\,mass}{molar\,mass}$

Complete answer:
A mole is the value given to $6.022\times {{10}^{23}}$particles, atoms or molecules of any substance. This is also known as Avogadro number. The value of mole can be calculated by dividing the given mass upon the molar mass of any substance.
We have been given an aluminum element with a mass of 54 grams; we have to find the number of moles in this mass. For this we will divide this given mass by the atomic mass of aluminum.
As we know the atomic mass of an atom is the sum of the protons and the neutrons of that atom. The number of protons is equal to the number of electrons which is equal to the atomic number of an atom. We have aluminum whose atomic number is 13. It has 13 protons and 14 neutrons in its atom, so its atomic mass is:
13 + 14 = 27 g/mol
Now calculating the number of moles using given mass and atomic mass of aluminum, we have,
Number of moles = $\dfrac{given\,mass}{molar\,mass}$
Number of moles = $\dfrac{54\,g}{27\,g\,mo{{l}^{-1}}}$
Number of moles = 2 moles
Hence, the number of moles in 54 g of Al is 2 moles.

Note:
The sum of number of protons and neutrons is taken to calculate the atomic mass of any atom because the mass of an atom is concentrated in the nucleus of that atom, and protons and neutrons are present in the nucleus of an atom and are called nucleons for this reason. Protons have a positive charge while neutrons are neutral.