Chapter 18 -> free energy and thermodynamics

What is the first law of thermodynamics?

energy cannot be created nor destroyed

Fewer steps generally results in a _____________

lower heat tax

why is a spontaneous irreversible?

there is a net release in energy when it proceeds in that direction; will only proceed in one direction

Describe a reversible process.

will proceed back and forth between 2 end conditions; at equilibrium, no change in free energy

If a process is _______________ in one direction, it must be ______________ in the opposite direction

spontaneous; nonspontaneous

Describe melting ice.

endothermic yet, will spontaneously melt above 0 ; when a solid melts particles have more freedom of movement; more freedom of motion increases randomness of a system

Define entropy.

When a system becomes more random and energy is released

what is the second law of thermodynamics?

for any spontaneous process the entropy of the universe increases; processes that increase entropy of the universe occur spontaneously; entropy is a state function

what are the two factors that determine whether a reaction is spontaneous?

enthalpy change and entropy change

What is ΔS?

the difference in randomness of reactants compared to products

What is S?

entropy a thermodynamic function that increases as the number of energetically equivalent ways of arranging the components increase

Describe gibbs free energy.

maximum amount of work energy that can be released to the surrounding by system for a constant temperature of pressure system; AKA a chemical potential, analogous to storing energy in a mechanical system

When ΔG in negative...

a process will be spontaneous

what is the third law of thermodynamics?

the entropy for a perfect crystal at 0K is zero

What is absolute entropy?

amount of energy it has due to dispersion of energy through its particles

Absolute entropy is always ___________

positive

what is the standard molar entropy symbol?

S°

standard molar entropy is a ________________

extensive property

standard molar entropy values are at ____________________

1 mole at 298K

The gas state has a much ______________ entropy than the liquid state at its particular temperature

larger

the liquid state has a _______________ entropy than the solid state at a particular temperature

larger

the larger the molar mass the _________ the entropy

larger

Heavier atoms allow ___________ dispersal of energy through the states.

more

the less constrained the structure of an allotrope is the ______________ its entropy

larger

Larger more complex molecules usually have ____________ entropy

larger

more energy states available means ...

more dispersal of energy

dissolved solids generally have _________ entropy, distributing particles throughout the mixture

larger

What is the ΔG equation?

Sum(nΔG)products - Sum(ΔG)reactants

What is free energy formation?

change in free energy when 1 mol of compound forms from its constituent elements in their standard states

What is the free energy formation of pure elements in their standard states?

zero

If a reaction can be expressed as a series of reactions, the sum of ΔG values of the individual reaction =

ΔG total reaction

If a reaction is reversed what happens to ΔG?

its sign is reversed

If the amount of materials is multiplied by a factor what happens to ΔG?

it is multiplied by the same factor

What is free energy?

amount of energy that is "free" to do work

What happens to heat in exothermic reactions?

heat is released due to enthalpy changes so it is not available to do work

ΔG is a ______________

theoretical limit

In a real reaction some of the free energy is ____________

lost as heat

real reactions are ___________________

irreversible

When K< 1 ΔG is

positive and spontaneous in the reverse direction

When K>1 ΔG is

negative and spontaneous in the forward direction

When K = 1 ΔG is

zero and reaction is at equilibrium

Slope is

ΔH/R

Y-intercept is

ΔS/R