## Chemistry: Atoms First (2nd Edition)

a. 0.9393 mol of $Fe_2O_3$ b. $2.17 \times 10^{-4}$ mol of $NO_2$ c. $2.5 \times 10^{-8}$ mol of $BF_3$
a. - Calculate or find the molar mass for $Fe_2O_3$: $Fe_2O_3$ : ( 55.85 $\times$ 2 )+ ( 16.00 $\times$ 3 )= 159.7 g/mol - Using the molar mass as a conversion factor, find the amount in moles: $$150.0 \space g \times \frac{1 \space mole}{ 159.7 \space g} = 0.9393 \space mole$$ b.- Calculate or find the molar mass for $NO_2$: $NO_2$ : ( 14.01 $\times$ 1 )+ ( 16.00 $\times$ 2 )= 46.01 g/mol - Using the molar mass as a conversion factor, find the amount in moles: $$10.0 \space mg \times \frac{1 \space g}{1000 \space mg} \times \frac{1 \space mole}{ 46.01 \space g} = 2.17 \times 10^{-4} \space mole$$ c.- Use avogadro's number as a conversion factor to find the amount of moles: $$1.5 \times 10^{16} \space BF_3 \times \frac{1 \space mol}{6.02 \times 10^{23} \space BF_3 } = 2.5 \times 10^{-8} \space mol \space BF_3$$