Question

how many moles of copper contain 5.67×10²² atoms?
a. 3.60×10³⁴ mols cu
b. 8.92×10⁻²⁰ mols cu
c. 9.42×10⁻² mols cu
d. 5.98×10¹⁰ mols cu

Explanation:

Step1: Recall Avogadro's number

Avogadro's number ($N_A$) is $6.022\times 10^{23}$ atoms/mol. We use the formula $n=\frac{N}{N_A}$, where $n$ is the number of moles, $N$ is the number of atoms.

Step2: Substitute values

Given $N = 5.67\times 10^{22}$ atoms and $N_A=6.022\times 10^{23}$ atoms/mol. Then $n=\frac{5.67\times 10^{22}}{6.022\times 10^{23}}$.

Step3: Calculate the result

$n=\frac{5.67}{6.022}\times10^{22 - 23}\approx0.942\times10^{- 1}=9.42\times 10^{-2}$ moles.

Answer:

C. $9.42\times 10^{-2}$ moles Cu