Answer:
Divide the given mass by its molar mass to get moles, then multiply times 6.022×1023 molecules 1 mol .
Converting between molecules and moles is done by either multiplying by or dividing by Avogadro's number:
1.To go from moles to molecules, multiply the number of moles by 6.02 x 1023.
2.To go from molecules to moles, divide the numbers of molecules by 6.02 x 1023.
We know that the number of moles is equal to the weight of the substance divided by its molar mass. Therefore, the number of moles in 19.82g of Mg is 0.81 mol.
Step-by-step explanation: