a copper atom has a mass of 1.06×10⁻²² g and a penny has a mass of 2.5 g. use this information to answer the…

Explanation:

Step1: Recall Avogadro's number

Avogadro's number $N_A = 6.022\times 10^{23}$ atoms/mol.

Step2: Calculate mass of 1 - mole of copper atoms

We know mass of 1 copper atom $m = 1.06\times 10^{-22}$ g. Mass of 1 - mole of copper atoms $M$ is given by $M=m\times N_A$. So $M=(1.06\times 10^{-22}\text{ g})\times(6.022\times 10^{23}\text{ atoms/mol})$. Using the rule of exponents $a^m\times a^n=a^{m + n}$, we have $M=(1.06\times6.022)\times10^{-22 + 23}\text{ g/mol}=63.8332\text{ g/mol}\approx63.8\text{ g}$ (3 significant digits).

Step3: Calculate moles of copper in a penny

Mass of penny $m_{penny}=2.5$ g. Number of moles $n$ of copper in a penny is given by $n=\frac{m_{penny}}{M}$. Substituting $m_{penny} = 2.5$ g and $M = 63.8$ g/mol, we get $n=\frac{2.5\text{ g}}{63.8\text{ g/mol}}=0.0392\text{ mol}\approx0.039\text{ mol}$ (2 significant digits).

Answer:

63.8 0.039