Answer:
Mole is a quantity corresponding to [tex]6.022\cdot 10^{23}[/tex] of units;
Difference in molar mass produces different masses for the same number of moles of two substances
Explanation:
We can define a mole very easily. Mole may be considered in any system, not only in chemistry. However, mole is mostly significant in chemistry.
Mole is simply a unit of measurement which is equal to the Avogadro's number of objects. That is, if we have 1 mole of some specific object, it means we have a total of Avogadro's number ([tex]6.022\cdot 10^{23}) of objects.
For example, let's say that we have 2 moles of stones. This means we have a total of:
[tex]2\cdot N_A = 2\cdot 6.022\cdot 10^{23} = 1.2044\cdot 10^{24}[/tex] stones.
Since this is a very huge number, we mainly use moles in chemistry to represent the number of molecules, atoms or ions.
You defined it perfectly: if we have 1 mol of C and 1 mol of Mg, they both contain the same number of atoms, that is, a total of [tex]6.022\cdot 10^{23}[/tex] atoms.
The problem is, however, that each individual atom of magnesium weighs more than the carbon atom. If you look at the periodic table, the molar mass of magnesium is 24.305 g/mol, while the molar mass of carbon is 12.011 g/mol. Magnesium atom is more than twice as heavy as carbon.
According to the molar mass, 1 mol of magnesium contains 24.305 grams and 1 mol of carbon contains 12.011 grams. This is essentially due to a different nature of atoms, they have different masses.
Take, for comparison, one stone and one feather. Although we have one of each, stones weigh more than feathers.
