CHEMISTRY

Energy Comparison of Fuels Hands-On Labs, Inc. Version 42-0154-00-02

Review the safety materials and wear goggles when working with chemicals. Read the entire exercise before you begin. Take time to organize the materials you will need and set aside a safe work space in which to complete the exercise.

Experiment Summary:

In this experiment, you will learn how various sources of fuels are formed. You will also assemble a calorimeter and measure the heat released from two different fuel sources. You will learn about the different types of fuels, combustion reactions, and differences between the energy content in fuel sources.

EXPERIMENT

© Hands-On Labs, Inc. www.HOLscience.com 1

Learning Objectives Upon completion of this laboratory, you will be able to:

● Describe the process of combustion.

● List different sources of fuels.

● Classify hydrocarbon fuel sources as biofuels or fossil fuels.

● Describe the formation of fossil fuels: coal, petroleum, and natural gas.

● Classify hydrocarbon’s molecules as saturated or unsaturated.

● Describe how energy is measured in calories or joules.

● Diagram a commercial calorimeter and describe the function of its components.

● Calculate the number of calories released per gram of fuel.

● Perform experiments with a homemade calorimeter.

● Calculate the density of water.

● Compare and contrast the energy content of diethylene glycol and paraffin.

Time Allocation: 2 hours

www.HOLscience.com 2 ©Hands-On Labs, Inc.

Experiment Energy Content of Fuels

Materials Student Supplied Materials

Quantity Item Description 1 Bottle of distilled water 1 Clock or timer (with second hand) 1 Matches or lighter

HOL Supplied Materials

Quantity Item Description 2 Aluminium foil, 30” x 24” 1 Beaker, 250 mL, glass 1 Burner-fuel, diethylene glycol 1 Burner stand 1 Candles, tea 1 Goggles 1 Pair of safety gloves 1 Graduated cylinder, 50 mL 1 Ruler, metric 1 Scale, digital 1 Thermometer, analog

Note: To fully and accurately complete all lab exercises, you will need access to:

1. A computer to upload digital camera images.

2. Basic photo editing software, such as Microsoft Word® or PowerPoint®, to add labels, leader lines, or text to digital photos.

3. Subject-specific textbook or appropriate reference resources from lecture content or other suggested resources.

Note: The packaging and/or materials in this LabPaq kit may differ slightly from that which is listed above. For an exact listing of materials, refer to the Contents List included in your LabPaq kit.

www.HOLscience.com 3 ©Hands-On Labs, Inc.

Experiment Energy Content of Fuels

Background Combustion, Biofuels, and Fossil Fuels

Fuels are storehouses for energy which exist in many different forms. For example, food is a fuel that supplies energy for metabolism, wood is a fuel that is burned to create warmth, and radioactive materials are fuels that power submarines and electrical generators. However, energy stored in a fuel must first be extracted before it is able to perform work. For fuels such as coal and oil, energy is extracted through a process called combustion. Combustion is an exothermic process, in which the fuel reacts with an oxidizing agent, such as oxygen, to produce heat. In a combustion reaction, heat (energy) is liberated when the fuel reacts with an oxidizing agent, forming different chemical compounds. For example, methane (CH4) reacts with oxygen to form carbon dioxide (CO2), water (H2O), and heat. This combustion equation is shown below:

4 2 2 2CH + 2O CO + 2H O + Heat→ The most common source of fuel is hydrocarbons. A hydrocarbon is an organic compound composed primarily of hydrogen and carbon atoms. Fuel sources composed of hydrocarbons are categorized as either biofuels or fossil fuels. Biofuels are derived from living biological organisms (hence the name “bio”) and can exist as solids, liquids, or gases. Biofuels are generally derived from renewable carbon sources, such as wood, waste materials, or corn. Ethanol, which can be produced from corn or sugar cane, has recently become a popular biofuel. However, there is currently a debate in political, scientific, and economic circles regarding how much net energy is derived from these biofuels after taking into account the fuel required to plant, grow, harvest, and process the crops, then to produce and distribute the fuel.

Fossil fuels are derived from the fossilized remains of organisms that lived millions of years ago; thus, they are not considered to be renewable energy sources. See Figure 1. The use of fossil fuels (coal, petroleum, and natural gas) was not a common practice until after the Industrial revolution. Coal and petroleum, however, were used prior to the Industrial Revolution for a variety of purposes. For example, petroleum was used in medicines and to waterproof boats and coal was used to make jewelry.

Based on fossil fuels used worldwide, it has been approximated

in recent years that it took plant matter somewhere between 400-500

years to yield this energy on our ancient Earth!

www.HOLscience.com 4 ©Hands-On Labs, Inc.

Experiment Energy Content of Fuels

Figure 1. How fossil fuels were formed. © U.S. Energy Information Administration

Energy in Fuel

Fuel sources differ in the amount of energy they contain. While determining the amount of energy in a fuel source can be complex, some generalizations can be made. First, longer-chain hydrocarbon molecules release more energy when they are combusted than shorter-chain molecules; second, even for the same energy source, the amount of energy can vary from batch to batch. Fossil fuels contain inconsistent amounts of carbon, hydrogen, sulfur, nitrogen and oxygen, and two fossil fuel samples may provide more or less energy, and more or less pollution, based on their chemical composition. For example, coal from the eastern United States contains more sulfur than coal from the western United States, so more sulfur dioxide is produced when eastern coal is burned. This has environmental importance, as sulfur dioxide is one of the main precursors of acid rain.

www.HOLscience.com 5 ©Hands-On Labs, Inc.

Experiment Energy Content of Fuels

Hydrocarbon molecules are classified as either saturated or unsaturated, depending on whether the carbon atoms are joined by single bonds or multiple (double or triple) bonds, respectively. A carbon atom can form up to four single bonds. In a saturated hydrocarbon, there are single bonds between all of the carbon atoms, and each carbon atom is completely surrounded (“saturated”) by hydrogen atoms. Butane, C4H10, is an example of a saturated hydrocarbon. See Figure 2A. In an unsaturated hydrocarbon, at least one of the bonds between the carbon atoms is either a double or triple bond. See Figure 2B. A saturated hydrocarbon contains, and therefore releases, more energy after combustion than an unsaturated hydrocarbon with the same number of carbon atoms.

Figure 2. A. Butane, a saturated hydrocarbon, consists of four carbon atoms and ten hydrogen atoms. B. Unsaturated hydrocarbon: Ethene (more commonly known as ethylene) with a double bond. C. Unsatu-

rated hydrocarbon: Ethyne (more commonly known as acetylene) with a triple bond.

Diethylene Glycol and Paraffin

In the LabPaq kit, the fuel canister contains diethylene glycol and the candle contains paraffin. Diethylene glycol is an organic, partially oxidized (contains oxygen) compound. See Figure 3. Diethylene glycol is used in industry as a solvent, as well as in brake fluid, lubricants, and facial creams.

Figure 3. Formula of diethylene glycol.

Paraffin is another term for saturated hydrocarbons. Most paraffins exist as a mixture of different length hydrocarbons and are a commonly used fuel source. Paraffins are also used in crayons, foods, toiletries, and paints. Most candles used today are formed from paraffin wax, although some candles are made of beeswax, soy, or even tallow (rendered beef fat). The hydrocarbon chains in paraffin wax range from C20H42 to C40H82 . See Figure 4.

www.HOLscience.com 6 ©Hands-On Labs, Inc.

Experiment Energy Content of Fuels

Figure 4. Formula of icosane (C20H42), a paraffin wax.

In this activity, you will burn two different fuels (diethylene glycol and paraffin) and compare the amount of energy released. Energy is measured in either calories or joules. One calorie is the amount of heat energy required to raise the temperature of one gram of water by one degree Celsius. The joule (J) is the Système International (SI) unit of energy. To convert from calories to joules, multiply the number of calories by 4.184, the number of joules in a calorie. The term “Calorie” (with a capital C) represents a kilocalorie (1000 calories) which is used when counting food calories.

Calorimeter

A calorimeter is a tool used to determine the number of calories of heat released from a material when it is combusted. See Figure 5. The energy from the fuel is transferred as heat to the water in a container, thereby raising the temperature of the water. The change in water temperature, as a result of the transferred heat, is used to determine the number of calories released by the fuel source.

Figure 5. Schematic of a commercial calorimeter. The motorized stirrer circulates the water located in the chamber, allowing for even heat distribution. The electrodes provide the charge (spark) to start burning the material. The thermometer records the temperature of water. The insulated container reduces the

loss of heat to the external environment, and the water surrounds the fuel container to absorb the heat from the burning material.

www.HOLscience.com 7 ©Hands-On Labs, Inc.

Experiment Energy Content of Fuels

Burning hydrocarbons, whether from fossil fuel or biofuel sources, releases carbon dioxide (CO2), which is an important greenhouse gas. Numerous scientific research studies have determined that the increase in atmospheric CO2 concentrations, from approximately 270 parts per million (ppm) in pre-industrial times to 392 ppm in 2011, is contributing to climate change that is impacting the environment and human society. The types of fuels we use vary greatly in their production of carbon dioxide. Among the fossil fuels, coal releases the largest quantity of CO2 per unit of energy produced, and natural gas produces the least. Nuclear energy does not produce carbon dioxide during electricity generation, but it has other safety concerns; additionally, there are indirect CO2 emissions associated with nuclear energy. Wind energy and solar energy do not produce any greenhouse gases when producing electricity. However, the fabrication, distribution, and installation of wind turbines and solar panels still rely on energy from fossil fuels.

There have been large advances in the creation and

use of renewable energy sources. Vegetable oil is being used in place of gas to run cars; solar energy

panels are becoming more common in residential housing; and car

manufactures are making advances in both hybrid and electric

automobiles.

www.HOLscience.com 8 ©Hands-On Labs, Inc.

Experiment Energy Content of Fuels

Order now and get 10% discount on all orders above $50 now!!The professional are ready and willing handle your assignment.

ORDER NOW »»