High School

A sample of \(\text{NO}_2\) occupies 11,200 mL at STP. What is the mass of the sample?

A) 18.6 g
B) 23.0 g
C) 42.4 g
D) 38.6 g

Answer :

Final answer:

The mass of the NO2 sample occupying 11,200 mL at STP is 23.0 g, calculated using the molar volume at STP and the molar mass of NO2.

Explanation:

To calculate the mass of an NO2 sample at STP (standard temperature and pressure), we use the molar volume of a gas at STP, which is 22.4 liters per mole. Given that NO2 occupies 11,200 mL at STP, we first convert the volume from milliliters to liters:

11,200 mL = 11.2 L

Next, we find out how many moles of NO2 we have:

Moles of NO2 = Volume of NO2 / Molar Volume at STP = 11.2 L / 22.4 L/mol = 0.5 mol

The molar mass of NO2 (M(NO2)) can be calculated from its chemical formula: M(NO2) = 14 (N) + 2(16) (O) = 46 g/mol

Now, we calculate the mass:

Mass of NO2 = Moles of NO2 x Molar Mass of NO2 = 0.5 mol x 46 g/mol = 23 g

Therefore, the correct answer is B) 23.0 g.