Car Parts

Consider a compact car straight off the assembly line. Where did its many parts come from? Perhaps its tires and windows were shipped from other manufacturers. But where did the materials used to make tires and windows come from? If you trace each car part back to its origins, you will eventually hit solid ground. A typical car is composed of no less than 30 minerals and substances, each of which was mined from Earth.

Iron and steel

The average car such as any of those shown in Figure 1, weighs approximately 1300 kg. Over 60 percent of the mass of a car is from the iron and steel, which make up parts of its frame and engine components. Steel is an alloy of iron and trace amounts of other elements, such as tungsten and manganese. To produce the iron and steel for the car, 3500 kg of raw ore is processed from the mineral hematite. The average car also contains almost 130 kg of aluminum, most of which comes from the mineral-ore bauxite and recycled material.

Lead

Galena is a lead sulfide mineral. Despite being composed of 86 percent lead, processing galena ore to remove lead is not an efficient process. It takes 210 kg of galena ore to make the 27 kg battery in a car. To process galena, the mineral must be separated from the surrounding rock, then the galena is heated to isolate the lead from the mineral, and finally, the molten lead is purified and poured into molds.

Precious metals

Gold, copper, platinum and nickel are also essential ingredients in many car parts. Gold was valued in prehistoric times because it doesn't rust, react with other elements, or break very easily. These are the same characteristics that make it invaluable for the vital electric systems in a car, such as the wiring of the air bags. In addition to gold, 20 kg of copper is used for wiring in the car, and 4 kg of nickel is used for plating the stainless steel on the car.

Quartz

Glass windshields cover about 25 percent of the surface of the average car. The glass is made from 77 kg, of industrial quartz, usually found as white sand. To make the glass, clean, white sand and a small amount of additives such as calcite, are heated to 1675°C, hot enough to fuse the quartz crystals together. The windshields are shaped while the mixture is still hot. The front windshield is a double paned layer of glass with a layer of vinyl in the middle, to keep you safe in a collision. The side windows are made from tempered glass, which is cooled extremely rapidly to make it more likely to break into tiny square pieces instead of deadly shards in an accident.

Petroleum products

Three and a half oil barrels worth of petroleum-based products are used to make a car. Lightweight components of petroleum are extracted from crude oil, and used to produce the plastics for the body of the car and interior panels. Heavier components are used to make rubber tires, in the paint, and in the synthetic fabric seat covers. Of course, some is also consumed as electricity for the assembly line that made the car. A very small amount is also used to fill the gas tank and lubricate the engine.

Teacher's Edition for Car Parts

Purpose

Students will apply what they have learned about rocks and minerals to how they impact the world around them. They will see that a car is composed of many of the Earth materials they learned about in this chapter.

Background

The raw materials for a car are almost exclusively extracted from mines. The raw ore must be processed and purified until it can be used. Students have probably not considered until now how much of an impact rocks and minerals have on their lives.

Teaching Strategies

• Before students read this feature, ask them to list the basic materials that cars are made of. • Write this statement on the board: If it is not grown, then it is mined. Ask students to volunteer explanations about what the statement means. (Every product we use has its origins either as plant matter, or it was extracted from Earth.) Even synthetic material such as polyester is produced from petroleum-based products.

• After reading the feature, bring some examples of common household items to class. These can include books, an electronic device, a pencil, a shoe, a toothbrush, a small mirror. With the students working in small groups, give each group an item and have them work together to determine where the raw materials came from for each item. While they are discussing, circulate among the groups and where necessary, help guide the discussions. Allow a few minutes for each group to present to the rest of that class what they observed.