16 terms

# Heat in Chemical Reactions

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Temperature
Average kinetic energy of matter (how fast the particles are moving)
Celsius
Temperature in the metric system that is base on water
Kelvin
Temperature that is a SI unit based on Absolute Zero
Enthalpy
Change in heat during a reaction due to breaking and making bonds
Endothermic
A reaction where heat is GAINED/ABSORBED (+ΔH) Potential energy is released
Exothermic
A reaction where heat is LOST/RELEASED (-ΔH) Potential energy is stored
Hess' Law
If a series of reactions are added together, the enthalpy change for the reaction will be the sum of the enthalpy changes for the individual steps (Whole = Sum of the Parts)
Rules of Hess' Law
1) If the coefficients of a rxn are multiplied by a factor, the ΔH is multiplied by the same factor. 2) If the rxn is REVERSED, the sign of the ΔH is REVERSED
Calorimetry
A temperature takes place in an insulated container so that the ΔT can be measured accurately (Assumes that heat which is released or absorbed from the reaction is absorbed or released by the surroundings)
Calorimeter
The insulated container where calorimetry reactions take place
Heat Curve
A graph that shows the physical changes caused by adding heat
Heat of Fusion
Energy needed to change from solid to liquid (No ΔT)
Heat of Vaporization
Energy needed to change from liquid to gas (No ΔT)
Entropy
(ΔS) Disorder or chaos or randomness. Reactions tend to proceed in the direction that produces more DISorder (-ΔH)
Gibb's Free Energy
Describes energy available to do work. Used to determine if reactions are spontaneous (Dependent on ΔH or ΔS)
Gibbs-Helmholtz Equation
(ΔG = ΔH - TΔS): Negative means Spontaneous, Positive means Nonspontaneous