Chemistry Grade 11

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Energy Trapped in Hydrocarbons
he whole world runs on energy—and so do you! Fossil fuels provide energy to power cars and heat buildings. Food provides energy to keep your body alive and warm. Both sources of energy come from organic compounds, such as hydrocarbons, sugars, and proteins. Green plants, algae, and plankton trap the Sun’s energy through the process of photosynthesis. After these organisms die, they are broken down by natural processes. Their remains accumulate on Earth’s surface. In some areas, these remains build up in thick layers, which are eventually covered by rock and soil. Under certain conditions, over billions of years, pressure changes these layers into something new: fossil fuels. Fossil fuels (such as coal, natural gas, and petroleum) are fuels that are made from fossilized organic materials. The trapped energy from the Sun is still present in fossil fuels. To use this energy, we need to extract it. Combustion, or burning, is the most common way to extract energy from fossil fuels. In this chapter, you will explore the ways in which our society obtains energy from fossil fuels. You will get a chance to measure exactly how much energy is obtained from an organic substance by doing your own combustion reaction. As well, you will learn how dangerous incomplete combustion reactions can be.


Chapter Preview 14.1 Formation and

Combustion Reactions
14.2 Thermochemical

14.3 Measuring Energy

14.4 The Technology of Heat

14.5 The Impact of Petroleum


Concepts and Skills Yo u W i l l N e e d

Before you begin this chapter, review the following concepts and skills: s

fuel, air mixture

spark plug

explaining bonding in molecular compounds (Chapter 3, section 3.3) writing and balancing chemical equations for different reactions (Chapter 4, section 4.1) significant digits (Chapter 1, section 1.2) problem solving in gas laws (Chapter 12, section 12.3) naming and drawing aliphatic compounds (Chapter 13, section 13.2)


combustion occurring here converts fuel into energy

exhaust gases


Fossil fuels take millions of years to accumulate. They are burned in minutes by the internal combustion engine of a car. How have fossil fuels changed your life? How long do you think our supplies of fossil fuels will last?



Chapter 14 Energy Trapped in Hydrocarbons • MHR


Section Preview/ Specific Expectations

Formation and Combustion Reactions
One of our most common uses of hydrocarbons is as fuel. (See Figure 14.1.) The combustion of fossil fuels gives us the energy we need to travel and to keep warm in cold climates. Fossil fuel combustion is also an important source of energy in the construction and manufacturing industries. As well, many power plants burn natural gas when generating electricity. Even goldsmiths use hydrocarbons, such as butane, as a heat source when crafting gold jewellery. At home, we often burn fossil fuels, such as natural gas, to cook our food. How do we get energy from these compounds? In this section, you will learn how complete and incomplete combustion can be expressed as chemical equations. Combustion in the presence of oxygen is a chemical property of all hydrocarbons. (In Chapter 13, you learned about some physical properties of hydrocarbons, such as boiling point and solubility.)

In this section, you will

write balanced chemical equations for the complete and incomplete combustion of hydrocarbons perform an experiment to produce and burn a hydrocarbon recognize the importance of hydrocarbons as fuels and as precursors for the production of petrochemicals identify the risks and benefits of the uses of hydrocarbons, for society and the environment communicate your understanding of the following terms: complete combustion, incomplete combustion





Figure 14.1

How are fossil fuels being used in these photographs?

578 MHR • Unit 5...
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