A chemist pours 1 mol of zinc granules into one beaker and 1 mol of zinc chloride powder into another beaker. What do the two samples have in common?

Answer is: two samples have in common same amount of substance and same number of particles.

1) There are same amount of substance in both beakers:

n (Zn) = 1 mol.

n (ZnCl ₂) = 1 mol.

2) There are same number of particles (atoms, molecules, ions) in both beakers:

N (Zn) = n (Zn) · Na.

N (Zn) = 1 mol · 6.023·10²³ 1/mol = 6.023·10²³ atoms of zinc.

N (ZnCl₂) = n (ZnCl₂) · Na.

N (ZnCl₂) = 1 mol · 6.023·10²³ 1/mol = 6.023·10²³ molecules of zinc (II) chloride.

Na - Avogadro number.