Answer:
5.9×10^20=158.875
Explanation:
mass of Cu = 2.501 g × 2.5% Cu/100 = 0.062525 g Cu
mass of Zn = 2.501 g × 97.5%/100 = 2.438475 g Zn
Calculate mol Cu: n = m/M; n = mole = ? mol; m = mass (g) = 0.062525 g Cu; M = molar mass (g/mol) = 63.546 g/mol Cun; Cu = 0.062525 g Cu/63.546 g/mol Cu = 0.00098393 mol Cu
Calculate the number of atoms of Cu:
1 mol atoms = 6.022×10^23 atoms
0.00098393 mol Cu × 6.022×10^23 atoms/mol = 5.9×10^20 atoms Cu to two significant figures
Calculate mol Zn:n = ? mol; m = 2.438475 g Zn; M = 65.39 g/mol Zn; n Zn = 2.438475 g Zn/65.39 g/mol Zn = 0.037291 mol Zn
Total number of atoms in a copper penny:
5.9×10^20 atoms
