temp and heat

• Temperature


  A physical quantity which expresses the degree of hotness and coldness of a body or a system
• Internal energy


  The sum of all molecular energy (kinetic energy + potential energy + other kinds of molecular energy)
• Increase in temperature


  Faster atoms and molecules, increase in internal energy
• Thermal equilibrium


  When two or more systems (or system and environment) have exchange of heat and reached the same temperature
• Zeroth law of thermodynamics: Two systems individually in thermal equilibrium with a third system are in thermal equilibrium with each other
• Celsius (°C), Fahrenheit (°F), Kelvin (K)

  Temperature scales, with Kelvin being the SI unit and absolute temperature scale
• Absolute zero is 0 Kelvin = -273.15 °C, the point where the system of molecules has its minimum possible total energy
• Converting between Celsius and Fahrenheit


  1. TC = 5/9 (TF-32)

  2. TF = 9/5 TC + 32
• Thermometers


  Instruments designed to measure temperature by detecting changes in physical properties of matter with temperature
• Thermometric properties


  • Volume expansion
  • Electrical properties (voltage generation)
  • Pressure
  • Radiation (infrared)
• Temperature ranges and their effects on the human body


  • < 33 °C: Hypothermia, metabolic processes may be affected
  • 35 - 36 °C: Core temperature in the early morning
  • 36 - 37.5 °C: Normal range for day-to-day activities
  • 38 °C: Moderate exercise
  • 39 - 40 °C: Hard exercise, unwell with fever
  • 42 °C: Hyperthermia, may cause irreversible damage to vital organs
• The body uses thermoregulation processes to maintain core temperature within the required range despite varying external temperatures and activity levels
• Linear thermal expansion


  The thermal expansion in any one-dimensional of a solid
• Holes in objects expand when temperature increases because every linear dimension changes in the same way
• Area thermal expansion


  The thermal expansion in two-dimensional of a solid
• Volume thermal expansion


  The thermal expansion in three-dimensional of a solid or liquid
• Water exhibits anomalous thermal expansion, decreasing in volume as temperature increases from 0°C to 4°C
• Thermal stress


  Stress that develops when a material is prevented from expanding or contracting due to a change in temperature
• Heat (Q)


  The energy transferred due to the change in temperature from a hot body/system to cold body/system
• Internal energy (U)


  The sum of all molecular energy (kinetic energy + potential energy + other kinds of molecular energy)
• The heat that flows from hot to cold originates in the internal energy of the hot substance (when no work is done)
• Specific heat capacity (c)


  The amount of heat required to raise the material's temperature by one unit per one-unit mass
• The value of specific heat depends on whether pressure or volume is held constant, but this distinction is not important for solids and liquids
• Molar heat capacity (C)


  The heat required per mole of a substance to change its temperature by one unit
• Calorimetry


  A technique used to measure heat flow in an isolated system where energy is conserved
• Latent heat


  The heat required for a substance to undergo phase change without a change in temperature
• Latent heat of fusion (Lf)


  The heat required per unit mass to change from solid to liquid (or vice versa)
• Latent heat of vaporization (Lv)


  The heat required per unit mass to change from liquid to gas (or vice versa)
• Relation of heat and temperature for water


  • Q = mciceΔT (for ice)
  • Q = +mLf (for melting/freezing)
  • Q = cwaterΔT (for liquid water)
  • Q = +mLv (for evaporation/condensation)