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62 Cards in this Set
- Front
- Back
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thermodynamics is the science of
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heat and work
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energy is defined as
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the capacity to do work
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the motion of atoms, molecules, or ions at the submicroscopic level
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thermal energy
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the motion of macroscopic objects like a moving tennis ball or automobile
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mechanical energy
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the movement of electrons through a conductor
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electrical energy
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the compression and expansion of the spaces between molecules in the transmission of sound
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acoustic energy
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energy possessed by a ball held above the floor and by water at the top of a water fall
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gravitational energy
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energy stored in fuels; all chemical reaction require this
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chemical energy
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the energy associated with the separation of two electrical charges
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electrostatic energy
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the temperature of an object is a measure of its
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ability to transfer energy as heat
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an object, or collection of objects, being studied
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system
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everything outside of the system that can exchange energy and/or matter with the system
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surroundings
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when all objects in the system are at the same temperature
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thermal equilibrium
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in thermal equilibrium, is there heat transfer on the molecular level?
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oh hell yeah
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the quantity of thermal energy lost by a hotter object and the quantity of thermal energy gained by a cooler object are numerically equal for
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an isolated system
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energy is transferred as heat from a system to its surroundings. energy of system decreases and energy of surroundings increases
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exothermic process
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energy is transferred as heat from the surroundings to the system, increasing the energy of the system, decreasing the energy of the surroundings
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endothermic process
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what's the si unit for heat
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joule
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1 joule equals
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1 kg*m^2/s^2
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the calorie is defined as the energy transferred as heat that is required
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to raise the temp of 1 g of pure liquid water from 14.5*C to 15.5*C
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1 calorie=
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4.184 J
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one joule is the kinetic energy of
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a 2 kg mass moving at 1 m/s
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when an object is heated/cooled, the quantity of energy transferred depends on these three things:
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the quantity of material
the magnitude of the temp change the identity of the material gaining or losing energy |
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specific heat capacity (C)
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the energy transferred as heat that is required to raise the temperature of 1 gram of a substance by one kelvin
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what's the unit for specific heat capacity
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J/g*K
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equation for energy gained or lost as heat when a given mass of a substance is warmed or cooled
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q = C x m x deltaT
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whats the specific heat capacity of liquid water
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4.184 J/g*K
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the energy transferred as heat to convert a substance from a solid at its melting point to a liquid
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heat of fusion
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the energy transferred as heat to convert a liquid at its boiling point to a vapor
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heat of vaporization
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what is constant throughout a change of state
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temp
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can you have work without energy?
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HELL NO
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if a system does work on its surroundings, the system's energy will
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decrease
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if work is done by the surroundings on a system, the energy of the system will
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increase
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changing from a solid to gas
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sublimation
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equation for change in energy of a system using heat and work
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deltaU = q + w
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the energy change for a system (deltaU) is the sum of
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the energy transferred as heat between the system and its surroundings (q) and the energy transferred as work between the system and its surroundings
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U, or the sum of the potential and kinetic energies of the atoms, molecules, or ions in the system
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internal energy
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equation for P-V work
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w = -P x deltaV
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a subscript p after q or w indicates
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conditions of constant pressure
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enthalpy equation at constant pressure
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delta H = q_p
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enthalpy equation
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H = U + PV
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negative values of deltaH specify that energy is transferred as heat from the
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system to the surroundings
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positive values of deltaH specify that energy is transferred as heat from the
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surroundings to the system
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changes in energy and enthalpy depend only on
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initial and final states
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a quantity that has the property of being the same no matter how you go from reactants to products
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state functions
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sign for standard reaction enthalpy
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delta_rH*
the * is actually a o |
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the most stable form of the substance in the physical state that exists at a pressure of 1 bar and at a specified temp
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standard state
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what's the common standard reaction enthalpy temp
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25 C
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what's the units for standard reaction enthalpy
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kJ/mol-rxn
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is enthalpy for state changes same in solid to liquid as liquid to gas
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hells no
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the energy evolved or required as heat in a chemical or physical process can be measured by
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calorimetry
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what instrument can measure the enthalpy change under constant pressure
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calorimeter
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what is often used to evaluate heats of combustion of fuels and the caloric value of foods
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constant volume calorimetry
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because the volume doesn't change in a constant volume calorimeter,
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energy transfer as work can't occur
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hess's law
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if a reaction is the sum of two or more other reactions, delta_rH* for the overall process is the sum of the delta_rH* values of those reactions
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the enthalpy change for the formation of 1 mol of a compound directly from its component elements in their standard states
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standard molar enthalpy of formation
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the enthalpy of formation of a compound does not necessarily correspond to a
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reaction that can be carried ou
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the standard enthalpy of formation for an element in its standard state
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zero
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sign for standard molar enthalpy of formation
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delta_fH*
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all combustion reactions are
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exothermic
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in most cases, product-favored reactions have
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negatvie values of delta_rH*
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in most cases, reactant favored reactions have
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positive values of delta_rH*
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