Chem II Ch. 17 Flashcards

Exothermic

Out of system (ΔH = negative)

Endothermic

Into system (ΔH = negative)

Entropy (S)

A thermodynamic function that increases with the number of energetically equivalent ways to arrange the components of a system to achieve a particular state

Microstates

Energetically equivalent ways to arrange the components of a system to achieve a particular state

solid, liquid, gas

Give the states of matter in order of increasing entropy

greater, translational, vibrational, rotational

High temperature leads to _____ (less/greater) entropy, due to increased _____, _____, and _____ motion

S = (k)ln(W) (W = number of microstates)

Write out the Boltzmann Equation

Third Law of Thermodynamics

At absolute zero, the entropy of a perfect crystalline substance is zero

Spontaneous reaction

A reaction that will occur under a given set of conditions

Non-spontaneous reaction

A reaction that will not occur under given conditions

Second Law of Thermodynamics

The entropy of the universe increases in a spontaneous process, and remains unchanged once equilibrium is reached

ΔG = ΔH - TΔS

Write out the Gibbs-Helmholtz Equation

Is the reaction spontaneous if ΔG is negative?

Yes

Is the reaction spontaneous if ΔG is positive?

No, but reverse reaction is spontaneous

Is the reaction spontaneous if ΔG is negative?

System is at equilibrium

Is the reaction spontaneous if ΔG is 0?

always spontaneous

If ΔH is negative and ΔS is positive, the reaction is _____ _____

only spontaneous at low temp

If ΔH is negative and ΔS is negative, the reaction is _____ _____ _____ _____ _____

only spontaneous at high temp

If ΔH is positive and ΔS is positive, the reaction is _____ _____ _____ _____ _____

0

ΔG^o_f is _ for all elements

0

At normal boiling point, liquid and vapor are in equilibrium, so ΔG^o = _

K

Represents the equilibrium constant, calculated using the equilibrium concentrations (or partial pressures) of the reactants and products

Q

Represents the reaction quotient, which describes the state of a reaction that is not yet at equilibrium

>

If K _ Q, the reaction will proceed forward, converting reactants into products

<

if K _ Q, the reaction will shift in the reverse direction, converting products back into reactants

ΔG = ΔG^o + RT(lnQ)

Free energy and equilibrium equation to get ΔG

ΔG^o = -RT(lnk)

Free energy and equilibrium equation to get ΔG^o

K = e^(-Δ^{G^o/RT)}

Free energy and equilibrium equation to get K

negative

If K > 1, ΔG^o is _____

0

If K = 1, ΔG^o is _____

positive

If K < 1, ΔG^o is _____

Gibbs free energy

Combines enthalpy (H), entropy (S), and temperature (T) into a single value that indicates the energy available to do work in a chemical or physical process