interaction between matter and heat

• When we feel warmth, it means that heat is transferring energy to our bodies; when we feel cold, that means heat is transferring energy away from our bodies.
• Heat is the transfer of energy due to a temperature difference.
• Temperature is defined in terms of the instrument we use to tell us how hot or cold an object is, based on a mechanism and scale invented by people.
• thermal energy—the energy associated with heat—is the average kinetic energy of the particles (molecules or atoms) in a substance.
• The three most commonly used temperature scales are the Fahrenheit, Celsius, and Kelvin scales.
• one degree on the Celsius scale is 1.8 times larger than one degree on the Fahrenheit scale (because 180/100=95=1.8)
• Kelvin scale is the temperature scale that is commonly used in science because it is an absolute temperature scale.
• Convert From Celsius to Fahrenheit

  T°F=9/5T°C+32
• Convert From Fahrenheit to Celsius

  T°C=5/9(T°F−32)
• Convert From Celsius to Kelvin

  TK=T°C+ 273.15
• Convert From Kelvin to Celsius

  T°C=TK−273.15
• Convert From Fahrenheit to Kelvin

  TK=5/9(T°F−32)+273.15
• Convert From Kelvin to Fahrenheit

  T°F=9/5(TK−273.15)+32
• One of the major effects of heat transfer is temperature change: Heating increases the temperature while cooling decreases it.
• The equation for heat transfer Q is

  Q = mcΔT
• Whenever there is a temperature difference, heat transfer occurs.
• There are three different heat transfer methods: conduction, convection, and radiation.
• Conduction is heat transfer through direct physical contact.
• Convection is heat transfer by the movement of a fluid(liquid).
• Radiation is a form of heat transfer that occurs when electromagnetic radiation is emitted or absorbed.
• Radiation is the only method of heat transfer where no medium is required, meaning that the heat doesn’t need to come into direct contact with or be transported by any matter.
• energy enters or leaves a system during a phase change without causing a temperature change in the system, it is known as latent heat (latent means hidden).
• the additional thermal energy acts to loosen bonds between molecules or atoms and causes a phase change
• Phase changes to a more energetic state include the following:

  • Melting —Solid to liquid
  • Vaporization —Liquid to gas (included boiling and evaporation)
  • Sublimation —Solid to gas
  • Ionization -Gas to plasma
• Phase changes to a less energetic state are as follows:

  • Condensation—Gas to liquid
  • Freezing—Liquid to solid
  • Recombination—Plasma to gas
  • Deposition-Gas to solid
• Energy is required to partially overcome the attractive forces between particles in a solid to form a liquid. That same energy must be removed for freezing to take place.
• heat capacity - amount of heat necessary to change the temperature of a substance by 1.00 °C
• latent heat of fusion - amount of heat needed to cause a phase change between solid and liquid
• latent heat - heat related to the phase change of a substance rather than a change of temperature
• latent heat of vaporization - amount of heat needed to cause a phase change between liquid and gas
• phase change - transition between solid, liquid, or gas states of a substance
• radiation energy transferred by electromagnetic waves
• thermal energy - average random kinetic energy of a molecule or an atom
• • During a phase change, a substance undergoes transition to a higher energy state when heat is added, or to a lower energy state when heat is removed.