Compare the number of atoms in 130 grams of zinc and 120 grams of iron.

Given:
m (Zn) = 130 g
m (Fe) = 120 g
NA = 6.02 * 10 ^ 23 mol − 1

Find:
N (Zn)? N (Fe)

Solution:
1) Calculate the amount of substance Zn:
n (Zn) = m (Zn) / M (Zn) = 130/65 = 2 mol;
2) Calculate the number of Zn atoms:
N (Zn) = n (Zn) * NA = 2 * 6.02 * 10 ^ 23 = 12.04 * 10 ^ 23;
3) Calculate the amount of the substance Fe:
n (Fe) = m (Fe) / M (Fe) = 120/56 = 2.14 mol;
4) Calculate the number of Fe atoms:
N (Fe) = n (Fe) * NA = 2.14 * 6.02 * 10 ^ 23 = 12.88 * 10 ^ 23;
5) Compare the number of Zn and Fe atoms:
N (Zn) <N (Fe).

Answer: The number of Fe atoms is greater than the number of Zn atoms.