Question

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part a
how many moles of gold atoms do $6.65 \times 10^{24}$ gold atoms constitute?
express your answer in moles to three significant figures.
number of moles = \boxed{} mol au

Explanation:

Step1: Recall Avogadro's number

Avogadro's number is \( 6.022 \times 10^{23} \) atoms/mol, which relates the number of atoms to moles. The formula to convert number of atoms to moles is \( \text{Moles} = \frac{\text{Number of atoms}}{\text{Avogadro's number}} \).

Step2: Substitute values into the formula

We have \( 6.65 \times 10^{24} \) gold atoms. So, \( \text{Moles} = \frac{6.65 \times 10^{24}}{6.022 \times 10^{23}} \).

Step3: Perform the calculation

First, divide the coefficients: \( \frac{6.65}{6.022} \approx 1.104 \). Then, divide the powers of 10: \( 10^{24 - 23}=10^{1} = 10 \). Multiply these results: \( 1.104\times10 = 11.04 \). Rounding to three significant figures gives \( 11.0 \).

Answer:

\( 11.0 \)