Rolling Reactions: The Car Chem Quiz

Staff

Which well-known gas law explains why car manufacturers recommend adjusting the pressure of your tires before you start on a trip?

In the 17th century, French physicist Guillaume Amontons was the first to observe that the pressure of a gas is directly proportional to its temperature. The law named in his honor applies to tires, as you know if you've ever checked air pressure before and after a trip. Driving a car causes the tires to flex, which heats up the air in the tires and increases the pressure.

Speaking of pressure, let’s say the volume and pressure in one of your tires falls to zero. What's the outside temperature?

Amontons’ law led, in the 19th century, to the concept of absolute zero -- the theoretical temperature at which the pressure of a gas becomes zero. In Celsius, that temperature is minus 273.16 degrees.

Quick! What chemical process is used to make modern rubber tires?

It sounds like a mind meld from Spock, but vulcanization is the process that leads to tires -- and a gazillion other products. Interestingly, the process was discovered by accident when a mixture of rubber, sulfur and lead spilled onto a hot stove.

Who discovered the process by which tires could be manufactured?

In 1735, French scientists first described the chemistry of a strange substance found in the bark of certain Brazilian trees, but it needed a good name. That name came in 1770, when Joseph Priestley called the substance "rubber" because it could be used to rub out pencil marks. Then, in 1839, Charles Goodyear devised a process to improve natural rubber's properties and make it commercially feasible to produce.

What’s the main chemical constituent of tire rubber?

Rubber gets its properties because it's made from elastic polymers, or elastomers, long chainlike molecules that recover their original shape after being stretched. Natural rubber is made from a particular elastomer called polyisoprene.

What would an exacting chemist call a car battery?

Your car needs something with a bit more juice than a few size-D alkaline batteries. That juice comes from a lead-acid storage battery, so named because lead and acid are its two most important components.

How many cells does a car battery typically have?

Most cars have batteries with six cells connected in series. Each cell produces approximately two volts, so the entire battery is rated at 12 volts.

Each cell in a car battery contains two types of plates. What chemicals make up these plates? (Hint: Remember what the exacting chemist calls a car battery.)

The cell in a car battery contains a series of plates -- positive lead dioxide plates and negative plates composed of straight lead. Nonconductive sheets called separators lie between the plates to keep them from touching.

What serves as the electrolyte in a car battery?

A lead-acid battery is an electrochemical device that converts chemical energy into electrical energy. In such a battery, an electrolyte -- sulfuric acid, in this case -- generates the electric current by reacting chemically with the plates.

When your car rusts, it falls victim to an electrochemical process known as corrosion. What's the chemical name of rust?

Rust occurs when metals react with an oxidizing agent, such as oxygen. When the metal contains iron, like the metal in your car, the reaction produces the reddish-brown compound known as iron oxide.

High-intensity discharge (HID) headlamps have become popular recently on U.S. cars. What noble gas is used in these lamps?

These lamps produce light when an electric arc passes between tungsten electrodes housed inside a glass tube. The tube is filled with both metal salts and a gas. The HID lamps used in the auto industry contain xenon and produce light with an eerie, bluish tint.

What type of "fuel" does the Honda FCX Clarity, a fuel cell electric vehicle, use?

The Honda FCX Clarity could be the car of the future. It doesn't run on gasoline but on compressed hydrogen stored in a tank at the back of the vehicle.

You saw this one coming. Which two chemicals react to produce the electricity in a fuel cell vehicle like the Honda FCX Clarity?

In a typical fuel cell, hydrogen combines with oxygen to make electricity. The electricity then powers the electric motor, which in turn propels the vehicle. The only byproducts of a fuel cell are heat and water.

So what kind of chemical reaction takes place inside a conventional car engine?

Ever hear of an internal combustion engine? Of course you have. It’s the kind of engine most cars have. The term combustion refers to a type of chemical reaction, one in which a fuel combines with an oxidizing element.

What's the oxidizing element in a gasoline engine?

Air is plentiful at the Earth's surface, so why not take advantage of it? Atmospheric oxygen, the type of oxygen found in air, is a great oxidizer, so car engines pull in air (oxygen) so it can combine chemically with gasoline or diesel fuel.

What's the job of a catalytic converter?

Catalytic converters are part of a car's emissions control system. Their job is to reduce the discharge of noxious gases -- gases produced by the combustion of fossil fuels -- from the tailpipe.

A catalytic converter gets its name because it contains two primary catalysts. What’s a catalyst?

A catalyst is like a good coach. It can motivate a team into action, but it can't actually participate in the game. Catalysts typically function to speed up chemical reactions, but they aren’t used at all in those reactions.

In a catalytic converter, carbon monoxide and hydrocarbons are transformed into these two chemicals:

Most modern catalytic converters have two types of catalysts. The first uses platinum and rhodium to reduce harmful nitrogen oxides to nitrogen and oxygen. The second uses platinum and palladium to oxidize hydrocarbons and carbon monoxide into water and carbon dioxide.

When an airbag deploys, what gas fills the bag?

During a collision, an airbag inflates with nitrogen gas in a fraction of a second. That gas is produced by a series of strong and rapid chemical reactions.

How many chemical reactions occur to inflate an airbag?

It takes three reactions to operate an airbag. Everything begins with a pellet containing a mixture of sodium azide, potassium nitrate and silicon dioxide. During a collision, a deceleration sensor ignites the gas mixture, causing sodium azide to decompose into nitrogen gas and sodium metal. The nitrogen gas inflates the bag, but sodium metal is potentially explosive, so a second reaction occurs to remove it. This involves sodium reacting with potassium nitrate to produce potassium oxide, sodium oxide and additional nitrogen gas. The metal oxides, also unstable, then react with silicon dioxide to produce silicate glass. And it all happens in 40 milliseconds.

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About This Quiz

Cars reveal a thing or two about chemistry, and we have the quiz to prove it. So hop in, buckle up and let's see if your car chem knowledge leaves you looking like Greased Lightning or blows up in your face.

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