thermochemistry

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DynamicPigeon38294

Cards (52)

  • High enthalpy systems tend to be hot, whereas low enthalpy systems tend to be cold.
  • Kinetic energy (energy produced by a moving object).
  • Radiant energy (solar energy from the sun)
  • Thermal energy (associated with the random motion of atoms and molecules).
  • Chemical energy (stored within the structural units of chemical substances).
  • Potential energy (energy available due to an object's position).
  • Temperature is a measure of the thermal energy (total kinetic energy of the particles of an object).
  • Joule is the SI unit of energy.
  • 1 J = 1 kg*m^2/s^2
  • Watt is the SI unit of power
  • 1 W = 1 J/s
  • Kilowatt-hour is a measure of power consumption.
  • 1 kWh = 3.6 Γ— 10^πŸ” J
  • The system is the specific part of the universe that is of interest in the study. Everything else is considered as the surroundings
  • First law of thermodynamics – energy can be converted from one form to another but cannot be created or destroyed.
  • w > 0 means work done on the system, w < 0 means work done by the system
  • q < 0 means that the system loses heat energy and the surroundings gains heat energy
  • a system that does no work but which transfers heat to the surroundings has q>0 and Ξ”E>0
  • a system that exchanges heat and mass is called an open system
  • unit of energy most commonly employed in chemistry is kJ
  • Heat is the transfer of thermal energy between two bodies that are at different temperatures.
  • The heat capacity (C) of a substance is the amount of heat (q) required to raise the temperature of a given quantity (m) of the substance by one degree Celsius.
  • The specific heat (s) of a substance is the amount of heat (q) required to raise the temperature of one gram of the substance by one degree Celsius
  • Exothermic process is any process that gives off heat. It transfers thermal energy from the system to the surroundings
  • Endothermic process is any process in which heat has to be supplied to the system from the surroundings.
  • Enthalpy (H) is used to quantify the heat flow into or out of a system in a process that occurs at constant pressure
  • Ξ”H = H (products) – H (reactants)
  • Ξ”H = heat given off or absorbed during a reaction at constant pressure
  • Β when H of products < H of reactants, Ξ”H < 0
  • when H of products > H of reactants, Ξ”H > 0
  • formula of constant pressure calorimetry is π’’π’“π’†π’‚π’„π’•π’Šπ’π’ = βˆ’π’’π’„π’‚π’π’π’“π’Šπ’Žπ’†π’•π’†r
  • formula of constant volume calorimetry is π‘žπ‘Ÿπ‘’π‘Žπ‘π‘‘π‘–π‘œπ‘› = βˆ’(π‘žπ‘π‘Žπ‘™π‘œπ‘Ÿπ‘–π‘šπ‘’π‘‘π‘’π‘Ÿ + π‘žπ»2𝑂)
  • second Law of Thermodynamics - the entropy (disorder) of the universe increases in a spontaneous process
  • Fuel is a material that burns readily with the release of significant amounts of energy
  • Coal is a rock that is can be burned due to its very high carbon content
  • coal is formed from terrestrial plant matter over many years of elevated temperature and pressure
  • Natural gas is naturally occurring gas trapped underground.
  • natural gas is made mainly of methane (CH4 ), ethane (C2H6 ), propane (C3H8 ) and smaller amounts of butane (C4H10) and pentane (C5H12).
  • CH4 (g) + O2 (g) β†’ CO2 (g) + H2O(g), Ξ”H = -890 kJ/mol
  • Crude oil is a naturally occurring liquid mixture of hydrocarbons formed from the decomposition of marine organisms that lived about 500 million years ago from extended periods of high temperature and pressure