Question | Answer |
Thermodynamics (Define) | The study of the laws that govern the conversion of energy from one form to another, the direction in which heat will flow, and the availability of energy to do work. |
Thermal energy | the energy that a substance possesses due to the, kinetic energy, or motion of its molecules. |
temperature | qa measure of the acerage kinetic energy of the molecules of a substance |
heat | the transfer of thermal energy from a hotter to a colder object |
law of conservation of energy | in any chemical reaction or physical process, energy can be converted, from one form to another, but neither is created nor destroyed. |
chemical potential energy | the energy stored in a chemical substance |
gas (properties) | assumes the shape and volume of its container
particles can move past one another
compressible
lots of free space between particles
flows easily
particles can move easily |
liquid (properties) | assumes the shape of the part of the container which it occupies
particles can move/ slide past one another
not easily compressible
little free space between particles
flows easily
particles can move/slide past one another |
solid (properties) | retains a fixed volume and shape
rigid - particles locked into place
not easily compressible
little free space between particles
does not flow easily
rigid- particles cannot move/ slide past one another |
q | the amount of heat transferred in joules(J) or Kilojouls(KJ)
Calories(Cal) or Kilocalories(kcal) |
m | mass of substance in g or Kg |
Cp | specific heat- amount of heat required to raise the temperature of one gram of that substance by one degree Celsius in [J/(g*C)] |
(Triangle) T | change in temperature
(T final - T initial) |
solid to liquid | melting |
liquid to solid | freezing |
liquid to gas | vaporization |
gas to liquid | condensation |
solid to gas | sublimation |
gas to solid | deposition |
critical point | the temperature beyond which the molecules of a substance have too much kinetic energy to stick together and form a liquid. |
triple point | the temperature and pressure at which all three phases can exist simultaneously in equilibrium |
first law of thermodynamics | energy can be changed from one form to another, but it cannot be created or destroyed. The total amount of energy and matter in the Universe remains constant, merely changing from one form to another. |
Enthalpy | Determines the overall heat of the reaction. It depends only upon the initial and final state of the reactants/products. |
Exothermic (bonds) | FORMED |
Endothermic (bonds) | BROKEN |
Bond energy | Hf = Change in bond energies broken -change in bond energies made |
Hesse's Law | Change in heat for the reaction will be equal to the sum of the enthalpy changes for the individual steps |
Single reactions | Change in Heat rxn = Change in Hf products - Change in Hf reactants |
Reversed multiple reactions | Change in Heat rxn = Change in Hf products + change in Hf reactants |
exothermic reactions | reactants are higher than products |
endothermic reactions | reactants are lower than products |