Chem/Phys Study Concepts Flashcards
An isothermal process occurs when?
The systems temperature is constant. If U=0 then Q=W
An adiabatic process occurs when?
No heat is exchanged between the system an enviroment Q=0 then U=-W
An isobaric process occurs when?
The systems pressure is constant. Does not alter first law so U=Q-W
An isovolumetric process occurs when?
The system has no change in pressure. With no change in pressure W=O and U=Q
What are standard conditions for state functions?
25 deg C (298 K), 1 atm Pressure, 1 M concentration
What are the State Functions?
Pressure, Density, Temp, Volume, Enthalpy, Internal Energy, Free energy
Mneumonic for State Functions?
When I am under Pressure and feeling dense, I watch TV and get HUGS
What state change is vaporization?
Liquid to gas
What state change is condensation?
Gas to liquid
What state change is sublimation?
solid to gas
What state change is deposition?
Gas to solid
Enthalpy is?
the thermal energy of the substance
What is the symbol for Enthalpy?
H
What is the Q value for Endothermic Processes?
♦Q>0
What is the Q value for Exothermic Processes?
♦Q<0
What is Hess’s Law?
That since Enthalpy is a State function its not path-depended therefore all enthalpy changes in a rxn are additive.
H=H1+H2+H3….etc
What is the formula for the enthalpy of a reaction, when bond dissociation comes into play?
Hrxn=Sum H(bonds broken)-SumH(bonds formed)
Bond dissociations:
What is the energy of bonds dissociating?
What is the energy of bonds formed?
Bonds dissociation energy >0
Bond Formation energy <0
*Breaking bonds requires energy
Forming bonds releases energy
Combustion:
How do alkane reactant size effect number of combustion products?
The larger the alkane reactant=more numerous the combustion sizes
What is the definition of Entropy?
It is a measure of spontaneous dispersal of energy at a specific temp: How much energy is spread out, and how widley spread out energy becomes
What is the change in free energy?
The maximum amount of energy released by a process at a constant temperature and pressure that is available to perform useful work
What is the formula for Gibb’s free energy?
DeltaG=DeltaH-TDeltaS
Gibb’s Free Energy:
If DeltaG<0 the reaction is?
G<0 the reaction is spontaneous
Gibb’s Free Energy:
If DeltaG=0 the reaction is?
The rxn is at equilibruim
(Q>Keq)=Ratio>1=DeltaG>0=Reverse Spontanous
(Q=Keq)=reaction is at equilibrum=DeltaG equals 0
I.P=Ksp =equilibrium
I.P>Ksp = supersaturated