ENERGETICS AND THERMOCHEMISTRY Flashcards
what is thermodynamics
the study of energy, how it is converted
first law of thermodynamics
Law of Conservation of Energy:
- energy can be converted from one form to the other
- energy is neither created nor destroyed
- total energy in a system remains constant
what is heat
thermal energy transferred from warmer to cooler body due to temp gradient. done to achieve thermal equilibrium
relationship between temperature and kinetic energy with more heat
directly proportional; as average kinetic energy increases, average temperature increases
what entropy
quantifying randomness/disorder in a system; how particles are arranged and distributed among energy states
the system; open system; closed system; isolated system
where the chemical reaction takes place; energy/matter transferred through boundaries; energy transferred through boundaries but not matter; matter cannot enter or exit, only move within
the surroundings
everything external to the reacting substances
endothermic reaction: meaning + characteristics
a system loses heat to the surroundings
- releases energy by building bonds
- negative enthalpy charge
- products have lower enthalpy than reactants
losing heat = less kinetic energy = less movement = building more bonds
endothermic reaction: meaning + characteristics
a system absorbs heat from its surroundings.
- requires energy to break bonds
- positive enthalpy charge
- products have higher enthalpy than reactants
enthalpy
the total heat content of a system. enthalpy itself cannot be measured, only change in enthalpy
standard enthalpy of reaction
enthalpy change carried out under standard conditions: 100 kPa, everything in standard state
two beakers of different sizes have the same temperatures. how does the heat compare.
the larger beak holds more volume, so it has more heat
how to calculate enthalpy change
q = mc△T
q = heat (J)
m = mass (g)
c = specific heat capacity
△T = temperature
what is specific heat capacity, c
the amount of heat needed to raise the temperature of 1 gram of the substance by 1 degrees C or 1 K
relationship between specific heat capacity (c) and temperature
lower specific heat capacity = higher temperature is achieved for the same amount of heat transferred/applied
