An investigation on the development of car safety and the importance of airbags

Chemistry experiment to simulate the inflation of an airbag in case of a car crash


Our aim is to create a chemical reaction to demonstrate the rapid inflation used in automobiles.

The inflation of an airbag is a very fast reaction, and the typical reactants used are a mixture of Calcium carbonate (CaCO3), Potassium nitrate (KNO3) and Silicon dioxide.  When a car crash occurs a sensor in the car's airbag triggers the reaction that will save the drivers life if the speed at which he is moving is greater than 16-24 km/h-1.  The nitrogen has to be produces more quickly than the driver hitting the steering wheel. The entire reaction is completed in less than 1/25 of 1 sec, because of the danger of this reaction, to demonstrate in a similar way the reaction that takes place in an airbag we have chosen to inflate a balloon using the  gas obtained by the reaction of a metal acid to produce sodium carbonate.


Ca(s) + 2HCl(aq) = Ca(aq) + (g) + O(l)


-Conical Flask

-Cork with delivery tube

-heat mats


-chemicals (baking soda)

- goggles (safety glasses)


• Gather all apparatus needed for the entire experiment

• Set up all apparatus

• Pour CaCo3 into the conical flask

• Add the HCl to the solution already in the conical flask

• Cover the flask with a cork delivery tube which will then allow to blow up the balloon

• Observe the reaction


Our experiment was successful in proving the function of an airbag of a car. Our experiment aimed to demonstrate the safety of the passengers of an automobile, through the use of an airbag. For our chemistry experiment we chose to adapt the airbag inflation to our IB program syllabus, hence by doing an experiment similar to the one we had already successfully completed during the school year.  was the element produced that mainly inflated the balloon, the reaction took place almost immediately. Hence, we have experimented the chemical reaction of a metal acid that produced Sodium Carbonate and inflated a balloon, the reaction was similar to the inflation of an airbag, proving the same chemistry principles.

Research Question:

How airbags managed to improve automobile safety.


The development of airbags began with the idea for a system that would save automobile drivers and passengers in a car accident, whether they were wearing their seat belts or not. Nowadays, airbags are compulsory in new cars and are designed to act as a supplementary safety device in addition to a seat belt.

Airbags were invented in 1953. The automobile industry started in the late 1950's to research airbags and soon discovered that there were many difficulties in the development of an airbag. Crash tests showed that for an airbag to be useful as a protective device, the bag must deploy and inflate within 40 milliseconds. The system must also be able to detect the difference between a severe crash and a minor fender-bender. These technological difficulties slowed the airbag creation process of 30 years, and in fact, it was in the mid 1980s that airbags started to be installed in all cars produced.

In recent years, increased reports in the media concerning deaths or serious injuries due to airbag deployment have led to a national discussion about the usefulness and "safety" of airbags. Questions are being raised as to whether airbags should be mandatory, and whether their safety can be improved. However,  as Graph 1 and 2 demonstrate, airbags have saved lives and have lowered the number of severe injuries.

Graph 1

This bar graph shows that there is a significantly higher reduction in moderate to serious head injuries for people using airbags and seat belts together than for people using only seat belts.


Graph 2

Deaths among drivers using both airbags and seat belts are 26% lower than among drivers using seat belts alone.

An airbag must be able to deploy in a matter of milliseconds from the initial collision impact. It must also be prevented from deploying when there is no collision. Hence, the first component of the airbag system is a sensor that can detect head-on collisions and immediately trigger the airbag's deployment. One of the simplest designs employed for the crash sensor is a steel ball that slides inside a smooth bore. The ball is held in place by a permanent magnet or by a stiff spring, which inhibit the ball's motion when the car drives over bumps or potholes. However, when the car decelerates very quickly, as in a head-on crash, the ball suddenly moves forward and turns on an electrical circuit, initiating the process of inflating the airbag.

Once the electrical circuit has been turned on by the sensor, a pellet of sodium azide (NaN3) is ignited. A rapid reaction occurs, generating nitrogen gas (N2). This gas fills a nylon or polyamide bag at a velocity of 150 to 250 miles per hour. This process, from the initial impact of the crash to full inflation of the airbags, takes only about 40 milliseconds (Movie 1). Ideally, the body of the driver (or passenger) should not hit the airbag while it is still inflating. In order for the airbag to cushion the head and torso with air for maximum protection, the airbag must begin to deflate as the body hits it. Otherwise, the high internal pressure of the airbag would create a surface as hard as stone, a device that wouldn't result useful to the passenger or driver.

Join now!


The kinetic theory of gases assumes that gases are ideal, thus that there are no interactions between molecules, and the size of the molecules is small compared to the free space between the molecules, but molecules are as a physical body that moves continually through space in random directions.

In a microscopic view, the pressure exerted on the walls of the container is the result of molecules colliding with the walls, and hence exerting force on the walls (Graph 3). When many molecules hit the wall, a large force is distributed over the surface of the wall, which ...

This is a preview of the whole essay