Thermochemistry Flashcards
Energy
the capacity to do work or to transfer heat
Heat
the flow of energy from a body at higher temperature to one at lower temperature when they are placed in thermal contact
Work
the movement of an object against some force
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-m2/s2. A related unit is the calorie: 4.184 J = 1 cal
Calorie
a unit of energy, it is the amount of energy needed to raise the temperature of 1 g of water by 1 oC from 14.5 oC to 15.5 oC. A related unit is the joule: 1 cal = 4.184 J
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
Force
a push or pull
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, ΔE, of a system in any process is equal to the heat, q, added to the system, plus the work, w, done on the system by its surroundings: ΔE = q + w
Internal Energy
The total energy possessed by a system. When a system undergoes a change, the change in internal energy, ΔE, is defined as the heat, q, added to the system, plus the work, w, done on the system by its surroundings: ΔE = q + w
Internal Energy Equation
ΔE = q + w
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; P, V,T, E, and H are state functions
Enthalpy
a quantity defined by the relationship H = E + PV; the enthalpy change, ΔH, for a reaction that occurs at constant pressure is the heat evolved or absorbed in the reaction: ΔH = qp
Enthalpy of Reaction
the enthalpy change associated with a chemical reaction
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
Endothermic Reaction Graph
Exothermic Reaction Graph
