How Do Airbags Work and Can They Really Kill You? Chemistry of Cars Ep.2

Summary

In this episode of 'The Chemistry of Cars', Charlotte Redcap explores the science behind airbags, answering the question of whether they can be lethal. She explains the evolution of airbag technology from its invention by John W. Hetrick to modern safety features. Redcap delves into the chemical components of airbags, including sodium azide, potassium nitrate, and silica, detailing how they react to produce gas for rapid inflation. She also discusses the engineering process to calculate the amount of sodium azide needed for safe deployment, emphasizing the improvements in airbag safety over the years.

Takeaways

• 🎓 Charlotte Roadcap, the resident chemist at TFL Car, recently graduated with a bachelor's degree in chemistry from CU Boulder and is starting a new show about the chemistry of cars.
• 💡 The concept of airbags was invented by John W. Hetrick, a retired industrial engineer, who was inspired to protect his daughter from a sudden stop by using his knowledge of compressed air from torpedoes.
• 📜 John Hetrick patented the airbag system in 1952, but it wasn't until the late 1980s that airbags became a common feature in cars due to challenges in timing and crash detection.
• 🚗 The first consumer car available with airbags was the 1974 Oldsmobile Toronado, where airbags were offered as an optional feature, not standard.
• 🛡 Inside an airbag, there are three chemical components: sodium azide, potassium nitrate, and silica, which react to produce a large amount of gas for inflation.
• 🔬 The chemical reaction within an airbag is initiated by a sensor that triggers a wire filament to heat up and decompose sodium azide into sodium and nitrogen gas.
• 🔄 The produced sodium is then mixed with potassium nitrate to form potassium oxide and sodium oxide, which, when mixed with silica, create a harmless alkaline silicate glass.
• 🧪 The amount of sodium azide needed in an airbag can be calculated through mechanical analysis, taking into account the desired pressure and the volume of the airbag.
• 🚀 Airbags inflate extremely rapidly, within 30 milliseconds, to provide protection during a collision.
• ⚖️ The force and pressure required to inflate an airbag are calculated based on the mass of the airbag, the acceleration, and the area over which it expands.
• ❗ Airbags can be lethal if not designed properly, as they deploy at high speeds and with significant force, but modern airbags have sensors to adjust inflation to the occupant's size for safety.

Q & A

Who is the host of the 'Chemistry of Cars' show?

The host of the 'Chemistry of Cars' show is Charlotte Roadcap.

What is the primary focus of the 'Chemistry of Cars' show?

The primary focus of the 'Chemistry of Cars' show is to explore the chemistry behind various aspects of cars, starting with the topic of airbags.

What is the big question Charlotte addresses in the script about airbags?

The big question Charlotte addresses is whether airbags can kill you, and she confirms that they can, but also discusses the advancements made by automakers to prevent such incidents.

Who is credited with the initial idea of the airbag?

John W. Hetrick is credited with the initial idea of the airbag, inspired by an incident where he and his wife instinctively protected their daughter from a potential car crash.

What year did John Hetrick patent the airbag system?

John Hetrick patented the airbag system in 1952.

What were the main difficulties that delayed the widespread availability of airbags in cars?

The main difficulties that delayed the widespread availability of airbags were issues with timing and crash severity detection.

Which was the first consumer car available with airbags?

The first consumer car available with airbags was the 1974 Oldsmobile Toronado, where they were offered as an option, not as a standard feature.

What are the three chemical components found inside an airbag?

The three chemical components found inside an airbag are sodium azide, potassium nitrate, and silica.

How does the chemical reaction in an airbag produce gas?

The chemical reaction in an airbag produces gas by heating a wire filament which decomposes sodium azide to form sodium and nitrogen gas. The sodium produced is then mixed with potassium nitrate to form potassium oxide and sodium oxide, which react with silica to form a harmless alkaline silicate glass.

What is the role of the wire filament in the airbag's chemical reaction?

The wire filament's role in the airbag's chemical reaction is to heat up and initiate the decomposition of sodium azide, which is the first step in producing the gas that inflates the airbag.

How is the amount of sodium azide needed for an airbag calculated?

The amount of sodium azide needed for an airbag is calculated through a mechanical analysis that considers the desired pressure inside the airbag, the volume it needs to expand to, and the ideal gas law at room temperature.

What is the maximum pressure inside an airbag during inflation?

The maximum pressure inside an airbag during inflation is about five pounds per square inch.

How do modern airbags adjust to the occupant's size?

Modern airbags can adjust inflation speed and pressure based on the occupant's size using sensors in the seats that detect weight and adjust the inflation accordingly.

What is the potential danger of the sodium produced in the airbag's chemical reaction?

The potential danger of the sodium produced in the airbag's chemical reaction is that sodium by itself is extremely dangerous to humans, so it needs to be mixed with potassium nitrate to form a safer compound.