Automobile airbags inflate following a collision. The impact triggers the follow

Question

Automobile airbags inflate following a collision. The impact triggers the following chemical reaction (shock sensitive reaction), during which a large volume of gas is produced to fill the airbag. 2 NaN3 (s) --> 2 Na (s) + 3 N2 (g)

a. What is the volume of N2 gas generated when 1.0 mol of NaN3 is used to inflate an airbag? Assume a temperature of 25 oC and a pressure of 1.0 atm inside the airbag after inflation.

b. How much work is done (in Joules) when 1.0 mol of NaN3 is consumed under these conditions?

c. Is this work done by the system or on the system?

d. Given the following enthalpies of formation, determine the standard enthalpy change for the reaction (deltaHo) per mol of NaN3 reacted.

deltaHof
NaN3 (s)
21.7 kJ/mol
N2 (g)
0 kJ/mol
Na (s)
0 kJ/mol

e. What is the change in internal energy for the reaction when 1.0 mol of NaN3 is consumed?

f. Calculate w, q and deltaE if 2.0 mol of NaN3 were consumed in a given experiment.

Explanation / Answer

a). 2 NaN3 ? 2 Na + 3 N2

V = nRT/P = 1.5 mol x 0.08205 l atm/mol K x 298 K / 1 atm = 37 L

or
(1.0 mol NaN3) x (3/2) x (22.414 L/mol) x ((25 + 273) / 273) = 37 L N2 Ans.

b). work = P delta V = 1 atm x 37 L = 1.05 x 105 x 37 N/m2 x 10-3 m3 atm = 3885 Joules Ans.

d).

You would take the products and subtract them from the reactants.
Delta H = [(2 x 0 kJ/mol) + (3 x 0 kJ/mol)] - [2 x 21.7 kJ/mol] = - 43.4 kJ/mol Ans.

e.).

Delta H =

2 mol of NaN3 -------> - 43.4 kJ . . . !

1 mol of NaN3 -----> - 43,4 / 2 = 21.7 kJ Ans.

f). work = 3885 *2 = 7770 Joules Ans.

Delta H =

2 mol of NaN3 -------> - 43.4 kJ

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.