## Chemistry 9th Edition

$1.30\text { grams/Liter}$
We assume that we are dealing with only one mole of air. 1 mole of gas at STP = 22.42 Liters $0.78\text{ mol$N_2$}*\frac{28.0134 \text{ grams$N_2$}}{1 \text{ mol$N_2$}}=22\text{ grams$N_2$}$ $0.21\text{ mol$O_2$}*\frac{31.9988 \text{ grams$O_2$}}{1 \text{ mol$O_2$}}=6.7\text{ grams$O_2$}$ $0.010\text{ mol Ar}*\frac{39.948\text{ grams Ar}}{1 \text{ mol Ar}}=0.40\text{ grams Ar}$ Total mass = $22+6.7+0.40=29.1\text{ grams}$ Volume = 22.42 L Density = $\frac{\text{Mass}}{\text{ Volume}}=\frac{29.1}{22.42}=1.30\text { grams/Liter}$