click below
click below
Normal Size Small Size show me how
Thermochemistry
NYS Regents Chemistry
Question | Answer |
---|---|
Heat of vaporization (Hv) | heat required to BOIL one gram of a liquid(see table B for water’s Hv) |
Heat of fusion (Hf) | heat required to MELT one gram of a solid (see table B for water’s Hf) |
Absolute zero | zero kelvin or –273 *C, the lowest possible temperature. |
Activation energy | energy required to take reactants or products to the top of a potential energy diagram. Every reaction has activation energy |
Spontaneous reaction | process that occurs on its own, without outside energy other than activation energy. Usually exothermic(decrease in enthalpy) with an increase in entropy |
Thermochemistry | the study of the heat changes that occur during chemical reactions |
Chemical potential energy | energy stored in chemical bonds |
System | the chemicals whose bonds are being broken and reformed during a reaction |
Surroundings | the air or water that will gain energy from the system during an exothermic reaction or lose energy to the system during an endothermic reaction. |
Law of Conservation of Energy | Energy cannot be created or destroyed, only transferred from one form to another |
Endothermic | a reaction that requires a net absorption of energy. The PE of the bonds increases while the KE of the surroundings decreases (Feels cold) |
Exothermic | a reaction that has a net release of energy. The PE of the bonds decreases while the KE of the surroundings increases (Feels warm) |
Specific Heat Capacity | the amount of energy (in joules or calories) required to raise the temp of 1 gram of a substance by 1 degree Celsius or Kelvin. |
Calorimeter | an insulated reaction apparatus that will allow for a more accurate measure of the change in temperature during a reaction. |
Enthalpy | the measure of heat energy of a chemical, generally expressed in joules or calories. |
Entropy | the amount of “chaos” or disorder of a chemical. Represented by delta S |
Heat of Reaction | the enthalpy change of a reaction. Also known as delta H, or “q” in the heat formulas. |
Fusion (the phase change) | melting; solid -> liquid |
Vaporization | boiling; liquid -> gas |
Sublimation | phase change solid -> gas |
Crystallization | phase change liquid -> solid; also known as freezing or solidification |
Deposition | phase change gas -> solid |
Condensation | phase change gas -> liquid |
Entropy | chaos of a system (ie. a gas has more entropy than a liquid) |