# What is meant by the term one mole of molecules?

Jan 2, 2017

$\text{One mole of molecules is like a dozen eggs...........}$

#### Explanation:

That is it is a convenient number for counting and calculation.

As far as I know, $\text{a dozen}$ is a convenient number for counting small quantities, because you can use your thumb on the tips and finger joints of either hand. Each finger has a tip and 2 joints, so we can use our thumb to count out to $12$ on one hand.

The mole is an equally useful number for calculation. There are $6.022 \times {10}^{23}$ individual items of stuff in a mole of stuff. Why should we use such an absurdly large number?

If I have $6.022 \times {10}^{23}$, $\text{one mole}$, of ""^1H atoms, I have a mass of $1 \cdot g$ precisely. If I have $6.022 \times {10}^{23}$, $\text{one mole}$, of ""^12C atoms, I have a mass of $12 \cdot g$ precisely. The mole is thus the link between the sub-micro world of atoms and molecules, which we cannot see but whose existence we can infer, with the macro world of grams, and kilograms, and litres, that which can measure out in a lab by various means (i.e. by measuring mass, volume, or by concentration).

The atomic masses are printed out on the Periodic Table. AS you use it, you will soon remember the masses of common atoms, hydrogen, oxygen, carbon, nitrogen.

And so you must comprehend this principle of chemical equivalence. If you know the mass of a quantity of chemicals of GIVEN formula, you know precisely how many atoms and how many molecules you have. And we can use it to calculate equivalent masses in calculations:

$C \left(s\right) + {O}_{2} \left(g\right) \rightarrow C {O}_{2} \left(g\right)$

I can take $12 \cdot g$ of carbon and react it precisley with $32 \cdot g$ of ${O}_{2}$, and get, precisely, $44 \cdot g$ of $C {O}_{2} \left(g\right)$. Can you tell me the numbers of $\text{carbon, oxygen, and carbon dioxide molecules?}$ I think you could be able to do this.

May 20, 2017

One mole of anything is $6.022 \times {10}^{23}$ objects of anything. You may recognize $6.022 \times {10}^{23}$ as Avogadro's number. One mole of molecules is $6.022 \times {10}^{23}$ molecules.

#### Explanation:

If you are asked to find the number of molecules in $1.000$ moles of a substance, you would multiply $1.000$ moles by $6.022 \times {10}^{23}$ molecules/mol.

1.000color(red)cancel(color(black)("moles"))xx(6.022xx10^23"molecules")/(1color(red)cancel(color(black)("mol")))=6.022xx10^24"molecules"

If you are asked to find the number of molecules in $6.23$ moles of a substance, you would multiply $6.23$ moles by $6.022 \times {10}^{23}$ molecules/mol.

6.23color(red)cancel(color(black)("moles"))xx(6.022xx10^23"molecules")/(1color(red)cancel(color(black)("mol")))=3.75xx10^24"molecules"

If you have moles, you can determine the number of individual units, such as atoms, molecules, formula units, electrons, protons, and neutrons by multiplying by $6.022 \times {10}^{23}$.