The first airbag was patented in 1953, however, the engineering of an airbag for use in passenger cars posed technological difficulties. Airbags became commonly available in passenger cars in the late 1980s.
1.
Three chemical reactions occur during an airbag deployment. The initial reaction triggerd by the sensor is the decomposition of sodium azide, NaN
3
, into sodium metal and nitrogen gas. Give the balanced chemical reaction equation for this reaction. a.
NaN
3
(aq)  Na(s) + N b.
NaN c.
2 NaN
3
3
(g)
3
(s)  Na(s) + 3 N(g)
(aq)  Na(s) + 3 N
(s)  2 Na(s) + 3 N
2
(g) d.
2 NaN
3 2
(g)
2.
The second reaction removes highly reactive sodium metal be reacting it with potassium nitrate to produce potassium oxide, sodium oxide, and nitrogen gas. Give the chemical formula for potassium nitrate. a.
KNO
3 b.
K
3
N c.
KNO
2 d.
K
2
NO
3 e.
K
2
NO
2
3.
What is the general formula for a Group 1 metal oxide? a.
MO b.
MO
2 c.
M
2 d.
M
2
O
O e.
M
3
O
2
3
4.
Give the balanced chemical reaction for the second reaction. a.
b.
4 Na + 2 KNO
2 Na + 2 K d.
8 Na + 2 K
3
2
NO
2
NO
 4 NaO + 2 KO + N c.
10 Na + 2 KNO
3
3
 5 Na
2
 4 Na
O + K
2
2
3
 2 NaO + 4 KO + N
2
O + N
2
2
O + 2 K
2
O + N e.
2 Na + 2 KNO
2
 2 NaO + 2 KO + N
2
2

Chapter 6 – Gases
5.
The two reactions together produce the nitrogen gas that inflates the airbag. The final reaction reacts the metal oxides with silicon dioxide to render the oxides harmless. Add the two nitrogen producing reactions together to get the net reaction for the production of the nitrogen gas. a.
NaN
3
+ KNO
2
 NaO + KO + 2 N
2 b.
8 Na + 2 NaN
3
+ 2 KNO
3
 5 Na
2
O + K
2
O + 4 N
2 c.
Na + NaN
3
+ K
2
NO
3
 NaO + 2 KO + 2 N
2 d.
3 Na + NaN
3 e.
2 Na + NaN
3
+ K
2
NO
3
+ KNO
3
 2 Na
2
O + K
2
 2 NaO + KO + 2 N
O + 2 N
2
2
6.
Pressure is defined as force per unit area. Force = mass x acceleration. A 2.00 kg airbag that reaches 200. mph by the end of inflation has an acceleration of 1.33 x 10 4 m/s 2 . What is the force it exerts during inflation? a. 6.65 x 10 3 kg·m/s 2 b. 6.65 x 10 3 g·m/s 2 c. 2.66 x 10 4 g·m/s 2 d. 2.66 x 10 4 kg·m/s 2
7.
If we assume the gas inside the airbag experiences the same force, what is the pressure the gas exerts on the front face of the airbag? Assume the airbag is cylindrical in shape with a volume of 60.0 L and a thickness (height) of 25.0 cm. V = area of front face x thickness of bag a. 111 kPa b. 11.1 kPa c. 11.1 Pa d. 111 Pa e. 27.7 kPa
8.
If the total pressure of the nitrogen gas reaches 2.10 atm at full inflation and a temperature of 25  C, how many moles of nitrogen gas must be present in the airbag? a. 0.414 mol b. 0.856 mol c. 5.15 mol d. 698 mol e. 3080 mol
9.
Using the equation for the net production of nitrogen gas, how many grams of NaN decompose to product this many moles of nitrogen gas? a. 100. kg b. 27.8 g
3
must c. 22.7 kg d. 13.5 g e. 167 g
10.
Sodium azide can be made by the following reaction. How many g of sodium amide is needed to produce the amount of sodium azide required in Question 9? a. 13.6 kg
NaNH b. 60.0 kg
2
+ N
2
O  c. 8.10 g
NaN
3
+ H
2
O d. 100. g e. 16.7 g