Thermochemistry Flashcard

thermodynaics
the study of energy and its transformation
thermochemistry
the relationship between chemical reactions and energy changes
kinetic energy
the energy that an object possesses by virtue of its motion
potential energy
the energy that an object possesses as a result of its composition or its position with respect to another object
joule
the SI unit of energy 1 kg*m^2/s^2; 4.184 J = 1 calorie
calorie
a unit of energy, it is the amount of energy needed to raise the temperature of 1 g of water 1*C
system
in thermodynamics, the portion of the universe that we single out for study; we must be careful to state exactly what the system contains and what transfers of energy it may have with its surroundings
surroundings
in thermodynamics, everything that lies outside the system that we study
work
the movement of an object against some force
force
a push or pull
heat
the flow of energy from a body at higher temperature to one at lower temperature when they are placed in thermal contact
energy
the capacity to do work or to transfer heat
internal energy
the total energy possessed by a system; when a system undergoes a change, the change in internal energy is defined as the heat added to the system
first law of thermodynamics
a statement that energy is conserved in any process; one way to express the law is that the change in internal energy of a system is any process is equal to the heat added to the system plus the work done on the system
endothermic
a process in which a system absorbs heat from its surroundings
exothermic
a process in which a system releases heat to its surroundings
state function
a property of a system that is determined by its state or condition and not by how it got to that state; its value is fixed when temperature, pressure, composition, and physical form are specified
pressure-volume work
work performed by expansion of a gas against a resisting pressure
enthalpy
a quantity defined by the relationship H = E + PV; the enthalpy change for a reaction that occurs at constant pressure is the heat evolved or absorbed in the reation
enthalpy of reaction
the enthalpy change associated with a chemical reaction
calorimetry
the experimental measurement of heat produced in chemical and physical processes
calorimeter
an apparatus that measures the heat released or absorbed in a chemical or physical process
heat capacity
the quantity of heat required to raise the temperature of a sample of matter by 1*C
molar heat capacity
the heat required to raise the temperature of one mole of substances by 1*C
specific heat
the heat capacity of 1 g of a substance; the heat required to raise the temperature of 1 g of substance by 1*C
bomb calorimeter
a device for measuring the heat evolved in the combustion of a substance under constant volume conditions
Hess’s law
the heat evolved in a given process can be expressed as the sum of the heats of several processes that when added, yield the process of interest
enthalpy of formation
the enthalpy change that accompanies the formation of a substance from the most stable forms of its component elements
standard enthalpy change
the change in enthalpy in a process when all reactants and products are in their stable forms at 1 atm pressure and a specified temperature, commonly 25*C
standard enthalpy of formation
the change in enthalpy that accompanies the formation of one mole of a substance from its elements, with all substances in their standard states
fuel value
the energy released when 1 g of a substance is combusted
fossil fuels
coal, oil, and natural gas, which are presently our major sources of energy
natural gas
a naturally occurring mixture of gaseous hydrocarbon compounds composed of hydrogen and carbon
petroleum
a naturally occurring combustible liquid composed of hundreds of hydrocarbons and other organic compounds
coal
a naturally occurring solid
renewable energy sources
energy such as solar energy, wind energy, and hydroelectric energy derived from essentially inexhaustible sources

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