## Chemistry: The Molecular Science (5th Edition)

$$5.59 *10^{20} molecules$$
From the previous problem, we found that there were 92.9 mmol copper in a penny. Using Avogadro's number, we find: $$\frac{92.9 mmol}{1} \frac{6.022*10^{23} molecules}{mol} = 5.59 *10^{20} molecules$$