Enthalpy of Formation

Standard Molar Enthalpies of Formation

• Chemists have measured the standard enthalpy changes for thousands of reactions

  • As a result, you can generate equations for almost any reaction

• Standard molar enthalpy of formation (∆H°f): The change in enthalpy when 1 mol of a compound is formed directly from its elements in their most stable state at standard ambient temp. and pressure

Formation Reactions

• Formation reactions can tell us how stable a substance is

  • Thermal stability: the ability of a substance to resist decomposition
    If decomposed, the ∆H°f reverses its sign

Energy Efficiency

Efficiency: the ratio of useful energy produced to energy used it its expression
Energy output: energy delivered in useable form
Energy input: energy used to fuel reaction/work

Using Energy Efficiently

• Humans use a great deal of electricity in their everyday lives

• In fact, we use about 58% of energy on just space heating in our homes

• The problem is, not all sources of energy are used as efficiently

  • It can be bad for our environment, so we must determine alternative methods of energy consumption

Efficiency of Natural Gas

• Natural gas can be an excellent source of energy in homes

  • In fact, it has a 97% efficiency rate

• However, it is not efficient in powerplants

  • It only amount to approx. 37% efficiency

• Why?
  Heat from the burning of the natural gas in water, uses energy. Additionally, the steam converts to mechanical energy to move the turbine, which then transforms to electrical energy