Chapter 19 - Thermodynamics

Question 0

Spontaneous processes

Answer 0

Those that can proceed without outside intervention.

Non spontaneous in reverse direction

Temperature matters!

Question 1

First law of thermodynamics

Answer 1

Energy cannot be created or destroyed
Total energy of universe is constant
Can be converted

Question 2

Reversible process

Answer 2

System and surroundings can be put back to original state by exactly reversing the process

Question 3

Irreversible process

Answer 3

Cannot be undone

Spontaneous processes are irreversible

Question 4

Entropy

Answer 4

Measure of randomness
Related to motion in molecules

Change in entropy equals entropy final minus entropy initial

q/t

Question 5

Isothermal process

Answer 5

A process occurring at constant temperature

For entropy the change is equal to heat that would be transferred if reversible divided by temperature

Question 6

Second law of thermodynamics

Answer 6

Entropy of the universe increases for spontaneous processes and does not change for reversible processes

Entropy of universe always increasing

Question 7

Average kinetic energy

Answer 7

Temperature

Question 8

Motion of molecules

Answer 8

Translational: movement of entire molecule from one place to another

Vibrational

Rotational: rotation of molecule about axis or sigma bonds

Question 9

Microstate

Answer 9

Snapshot of molecule notion in a thermodynamic system

Question 10

Entropy equation with microstates

Answer 10

S= k lnW

K is 1.38e-23
W is microstates

Question 11

Number of microstates increase when

Answer 11

Entropy increases
Temperature increases
Volume increases
Molecules increase

Question 12

Entropy in solutions

Answer 12

When solid is dissolves in a solvent, entropy increases

Question 13

Third law of thermodynamics

Answer 13

The entropy of pure crystalline substance at absolute zero is 0

Question 14

Standard entropies

Answer 14

Molar entropy values of substances in their standard state

Tend to increase with increasing molar mass

Question 15

Size of molecules and entropy

Answer 15

Larger and more complex molecules have greater entropies

Question 16

Entropy changes eqn

Answer 16

Delta S = sum of m delta S products minus sum of n delta S reactants

Question 17

Gibbs free energy

Answer 17

When delta G is negative a process is spontaneous
If positive then spontaneous in reverse direction
If zero it is at equilibrium

Question 18

Free energy changes eqn

Answer 18

Delta G = delta H - T * delta S

Enthalpy and entropy terms respectively

Question 19

Under any conditions the free energy change can be found with

Answer 19

Delta G = delta G standard + RTlnQ

Rearranged to be

K = e^(-delta G standard/RT)