Fossil Fuels

Fossil fuels, also known as hydrocarbons, are substances that contain carbon and hydrogen. Examples of fossil fuels: Coal, crude oil (petroleum) and natural gas. Natural gas consists mainly of methane ($\text{CH}_{4}$). Complete combustion of fossil fuels (aka burning of fossil fuels) produces carbon dioxide and water. It is an exothermic reaction. A large amount of heat …

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Bond Breaking and Bond Forming

Bond breaking and bond forming occurs during a chemical reaction. The energy changes in chemical reactions are caused by bond breaking and bond forming. Breaking a bond is endothermic. Energy is taken in to break a chemical bond. E.g. $\text{H}-\text{H} \left( \text{g} \right) \rightarrow \text{H}\left( \text{g} \right) + \text{H} \left( \text{g}\right)$, whereby $\Delta \text{H} =+436 …

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Endothermic Reactions

A chemical reaction that involves a gain of heat energy from the surroundings, resulting in a drop in the temperature of the surroundings is called an endothermic reaction. Summarised version: A reaction that takes in heat from the surroundings. The temperature of the surroundings decreases. (The reaction container becomes colder.) The energy content of the …

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