Question

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 question below. be sure your answers have the correct number of significant digits. what is the mass of 1 mole of copper atoms? g

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

Multiply mass of one copper atom by Avogadro's number. Let $m_1$ be mass of one copper atom ($m_1=1.06\times 10^{-22}$ g) and $m$ be mass of 1 - mole of copper atoms. Then $m = m_1\times N_A$.
$m=(1.06\times 10^{-22}\text{ g})\times(6.022\times 10^{23}\text{ atoms/mol})$
Using the rule of exponents $a^m\times a^n=a^{m + n}$, we have $m=(1.06\times6.022)\times10^{-22 + 23}\text{ g/mol}$.
$1.06\times6.022 = 6.38332$, and $-22 + 23=1$. So $m = 63.8332$ g/mol. Rounding to 3 significant digits (since 1.06 has 3 significant digits), $m\approx63.8$ g/mol.

Answer:

63.8 g