Studied by 3 peopleEnthalpy change
________ depends on the physical states of reactants and products and these states must be specified.
Delta H
________ can be determined experimentally by measuring heat flow for a reaction at constant pressure.
If delta V is + →
expansion of gas; system does work on surroundings and w is negative.
internal energy
Like ________ E, both P and V are state functions.
Surroundings
________: everything outside of the system.
PV work
________ "is work involved in expansion or compression of gases.
sign of delta H
Reversing the direction of a reaction changes the ________.
enthalpy change
If the coefficients of a chemical reaction are multiplied by some factor, the ________ must also be multiplied by that factor.
delta H
If ________ is positive, the reaction is endothermic.
Internal energy
________, U, of a system: the sum of ALL potential and kinetic energies of the components of the system.
delta H
If ________ is negative, the reaction is exothermic.
System
part of the universe that we are studying
Surroundings
everything outside of the system
Open system
matter & energy exchange with surroundings
Closed system
exchanges energy as work and/or heat (but not matter)
Isolated system
neither matter nor energy exchanged
First law of thermodynamics
energy is conserved
Internal energy, U, of a system
the sum of ALL potential and kinetic energies of the components of the system
delta U = Ufinal
Uinitial
At constant pressure
w = -P(delta V)
If delta V is
→ compression of gas; work is done on the system and w is positive
At constant pressure
delta H = delta E + P(delta V)
Heat capacity
the amount of heat required to raise the temperature of an object by one degree C or K
Specific heat
the heat capacity of one gram of a substance; Cs
Enthalpy of formation
the enthalpy change for the reaction in which one mole of a substance is made from its constituent elements in their elemental (most stable) forms
Standard enthalpies of formation
measured under standard conditions
Note
Flashcard