combustion

Examples of combustion in the following topics:

• Combustion Analysis

  • Combustion analysis is commonly used to analyze samples of unknown chemical formula.
  • One example of a simple combustion reaction is the combustion of methane:
  • Another common example of combustion is the burning of wood to produce thermal energy.
  • Combustion analysis can also be performed using a CHN analyzer, which uses gas chromatography to analyze the combustion products.
  • Energy is released in the form of flames as the fuel combusts.

• Combustion

  • The combustion of carbon compounds, especially hydrocarbons, has been the most important source of heat energy for human civilizations throughout recorded history.
  • Precise heats of combustion measurements can provide useful iinformation about the structure of molecules.
  • From the previous discussion, we might expect isomers to have identical heats of combustion.
  • Thus, the heat of combustion of pentane is –782 kcal/mole, but that of its 2,2-dimethylpropane (neopentane) isomer is –777 kcal/mole.
  • The following table lists heat of combustion data for some simple cycloalkanes and compares these with the increase per CH2 unit for long chain alkanes.

• Constant-Volume Calorimetry

  • Constant-volume calorimeters, such as bomb calorimeters, are used to measure the heat of combustion of a reaction.
  • A bomb calorimeter is a type of constant-volume calorimeter used to measure a particular reaction's heat of combustion.
  • As such, bomb calorimeters are built to withstand the large pressures produced from the gaseous products in these combustion reactions.
  • Once the sample is completely combusted, the heat released in the reaction transfers to the water and the calorimeter.
  • A schematic representation of a bomb calorimeter used for the measurement of heats of combustion.

• Indoor Pollution: CO and CO2

  • Carbon monoxide and carbon dioxide are products of combustion reactions; in large amounts, carbon monoxide can cause suffocation.
  • Carbon dioxide and carbon monoxide are the products of combustion reactions, such as the burning of coal, wood, and natural gas, or the use of modern combustion engines (most frequently used in cars).
  • Carbon monoxide is often the product of incomplete combustion reactions.
  • In the presence of adequate oxygen, combustion reactions will usually produce carbon dioxide.

• Types of Redox Reactions

  • The five main types of redox reactions are combination, decomposition, displacement, combustion, and disproportionation.
  • Keep this in mind as we look at the five main types of redox reactions: combination, decomposition, displacement, combustion, and disproportion.
  • Combustion reactions always involve oxygen and an organic fuel.
  • In the following image, we see methane combusting to release energy.
  • This is an example of a combustion reaction, a redox process.

• Physical and Chemical Properties of Matter

  • Heat of combustion is the energy released when a compound undergoes complete combustion (burning) with oxygen.
  • The symbol for the heat of combustion is ΔHc.

• Detonation Waves

  • One could have either a release of energy through the shock (like combustion) or a consumption of energy (like ionization).
  • This special situation often arises when the combustion itself creates the shock.
  • The detonation adiabat below the Jouguet point $E$ cannot be reached if the combustion begins after the gas is compressed.

• Reactions of Alkanes

  • The most important reaction that alkanes undergo is combustion.
  • The combustion of methane is shown:

• Fuel cells

  • Fuel cells require no combustion, have no moving parts, are silent, and are virtually pollution-free.

• Standard Enthalpy of Reaction

  • Calculate the standard enthalpy of reaction for the combustion of methane:
  • As we would expect, the standard enthalpy for this combustion reaction is strongly exothermic.