# Question #162a7

Nov 25, 2014

A mole is a collection that contains $6.02 \cdot {10}^{23}$ atoms/ molecules /ions of a substance.

1 mole of $B {F}_{3}$ has $6.02 \cdot {10}^{23}$ molecules.

To calculate the number of molecules in 1.25 moles of $B {F}_{3}$ we will use dimensional analysis.

$1.25$ $\text{moles}$ $B {F}_{3} \cdot \left(6.022 \cdot {10}^{23} \text{ molecules") / ("1 mol } B {F}_{3}\right)$

$1.25 \cdot \frac{6.022 \cdot {10}^{23} \text{molecules}}{1}$

$7.53 \cdot {10}^{23} \text{molecules}$.