Approximately how many atoms of copper are present in a typical U.S. penny?

• A. about 1.0 × 10^{18}
• B. about 3.5 × 10^{25}
• C. about 2.2 × 10^{22}
• D. about 6.0 × 10^{23}

Answer: (C)

Verified step by step guidance

1. Determine the mass of copper in a typical U.S. penny. Since modern pennies are mostly zinc with a thin copper coating, assume the penny is made entirely of copper for estimation or use the actual copper mass if known (for example, about 2.5 grams for older pennies).
2. Find the molar mass of copper, which is approximately 63.55 g/mol. This tells us how many grams are in one mole of copper atoms.
3. Calculate the number of moles of copper in the penny using the formula: \(\text{moles of Cu} = \frac{\text{mass of Cu (g)}}{\text{molar mass of Cu (g/mol)}}\).
4. Use Avogadro's number, \$6.022 \times 10^{23}\( atoms/mol, to convert moles of copper to number of atoms: \)\text{number of atoms} = \text{moles of Cu} \times 6.022 \times 10^{23}$.
5. Combine these steps to estimate the total number of copper atoms in the penny, which will give a value close to \$2.2 \times 10^{22}$ atoms.