Hydrocarbon Combustion

Hydrocarbons and Combustion

• A hydrocarbon is a compound made up of only carbon and hydrogen atoms.
• Many fuels are primarily composed of hydrocarbons.
• Hydrocarbon combustion reaction: hydrocarbon + oxygen → water + carbon dioxide
• Combustion is also an oxidation reaction, as it involves the reaction of a substance with oxygen.

Testing for Products of Combustion

• Limewater turns cloudy to indicate the presence of carbon dioxide.
• Cobalt chloride paper turns pink to indicate the presence of water.

Conservation of Mass

• The law of conservation of mass states that the mass of reactants is equal to the mass of products in a chemical reaction.
• Metals can appear to gain mass when heated in air, but this is due to the mass of oxygen that reacts with the metal.
• When a hydrocarbon fuel combusts, it appears to lose mass because the products of the reaction (carbon dioxide, water vapor) are lost into the air.

The Fire Triangle and Fire Extinguishers

• The fire triangle consists of three essential factors for a fire to burn: fuel, oxygen, and heat.
• Removing any one of these factors can extinguish a fire.
• Different types of fire extinguishers work in various ways, including:
  • Water extinguishers: remove heat
  • Powder and carbon dioxide extinguishers: exclude oxygen
  • Foam extinguishers: remove heat and exclude oxygen

Hazard Symbols and Air Pollution

• Hazard symbols are used to indicate the potential dangers of a substance and the necessary precautions for handling it.
• Burning fossil fuels can lead to air pollution, which can harm habitats and organisms.
• Incomplete combustion of fossil fuels can produce pollutants such as carbon monoxide, sulfur dioxide, and nitrogen oxides.

Acid Rain and the Greenhouse Effect

• Acid rain is formed when sulfur dioxide and nitrogen oxides in the air react with water.
• The greenhouse effect is the warming of the Earth's surface due to greenhouse gases such as carbon dioxide in the atmosphere.
• Global warming is the predicted result of an increase in the Earth's temperature due to the increased levels of carbon dioxide in the atmosphere, leading to climate change.

Key Vocabulary

• Law of conservation of mass: the idea that mass is not lost or gained during a chemical reaction.
• Metal: an element that is shiny when polished, conducts heat and electricity well, is malleable and flexible, and often has a high melting point.
• Metal oxide: a metal that has combined with oxygen in a chemical reaction.
• Non-metal: an element that is not shiny and does not conduct heat and electricity well.
• Oxidation: reacting with oxygen.
• Oxide: a compound that contains oxygen, often formed through the reaction of a metal with oxygen.