Question

How many atoms of lead are in 3.5 moles of lead?

Answer 1

Answer:

2.1 × 10²⁴ atoms Pb

Explanation:

Avogadro's number: 6.022 × 10²³

Step 1: Find conversions

1 mol Pb = 6.022 × 10²³ atoms Pb

Step 2: Use Dimensional Analysis

$3.5 \hspace{3} mol \hspace{3} Pb(\frac{6.022(10)^{23} \hspace{3} atoms \hspace{3} Pb}{1 \hspace{3} mol \hspace{3} Pb} )$ = 2.107 × 10²⁴ atoms Pb

Step 3: Simplify

We have 2 sig figs.

2.107 × 10²⁴ atoms Pb ≈ 2.1 × 10²⁴ atoms Pb