Question

An automobile airbag inflates when sodium trinitride is converted to sodium metal and nitrogen gas.

a. Write the balanced chemical reaction.

b. What volume of nitrogen gas is produced if 3.56 g of sodium trinitride reacts completely at 850. mmHg and 304 K?

c. How many grams of sodium metal will be produced if 560. mL of nitrogen gas is also produced at 3.45 atm and 21.°C?

d. What volume of nitrogen gas would be produced if 100.g of sodium trinitride completely reacted at STP?

Answer 1

Part a

Balanced chemical reaction

2NaN3(s) -> 2Na(s) + 3N2(g)

sodium trinitride = sodium metal + nitrogen gas

Part b

molecular mass of NaN3 = 65.01 g/mol

Moles of NaN3 = mass/molecular weight

= 3.56/65.01 = 0.05476 moles

2 moles NaN3 produces = 3 moles N2

0.05476 moles NaN3 produces = 0.05476*3/2 moles N2

= 0.08214 moles N2

the volume of N2 gas

V = nRT/P

=( 0.08214*0.0821*304) / (850 mmHg x 1atm/760mmHg)

= 1.833 L

Part C

Moles of N2 gas

n = PV/RT

= 3.45 atm x 0.560 L / 0.0821 x 294K

n = 0.08

From the stoichiometry of the reaction

3 N2 = 2 Na

Sodium metal produce

= 2 moles of Na x 0.08 moles of N2/3moles of N2

= 0.0533 moles

Mass of sodium metal = moles x molecular weight

= 0.0533 x 23 = 1.2259 g

Part d

Moles of NaN3 = mass/molecular weight

= 100/65.01 = 1.538 moles

V = nRT/P

= 1.538 moles x 0.0821 L-atm /mol-K x 273 / 1atm

= 34.47 L

= 34470 mL