Thermodynamics Chem Unit 4

∆H=(-) & ∆S=(+) has a (exp)

Reaction that always happens

∆H=(-) & ∆S=(+) makes

∆G=(-)

∆H=(+) & ∆S=(-) has a (exp)

Reaction that never happens

∆H=(+) & ∆S=(-) makes

∆G = (+)

∆H=(+) & ∆S=(+) has a (exp)

temperature dependent process

∆H=(+) & ∆S=(+) needs (exp)

High temp to occur

∆H=(-) & ∆S=(-) has a (exp)

temperature dependent process

∆H=(-) & ∆S=(-) (exp)

Low temp to occur

What state function allows for the determination of spontaneity

∆G°sys

NaCl dissolving in water is endothermic. What is true about thermodynamic signs?

Change in entropy of system must be positive

Phase transition occurs

Constant temp while forward & reverse rxns are same rate

When rate of forward and reverse rxns are same

free energy = 0

Phase transition temp

∆H/∆S

What is the temperature of ethanol is the standard enthalpy of vaporization is 39 kJ and the standard entropy of vaporization is 110 J/K?

81°C

Which of the following systems is at equilibrium?

A glass of ice water at 273K (0°C)

∆G°f shows

whether compound is stable

If energy is released

compound formed is at the bottom of free energy hill

Positive ∆G°f

unstable and compound decomposed over time

Negative ∆G°f

stable

If energy is put in

compound is at top of energy hill

How does stability impact speed of decomposition?

No effect

What must stay constant for system at equilibrium?

State functions

What are the state functions?

SHUT GVT

Where is the action in a system at equilibrium?

Molecular level

Energy to break bonds is

positive

Energy to form bonds is

negative

Molecules in their native state at STP have

H°f=0

What type of system is the universe

isolated

Internal energy of system includes

potential and kinetic energy

For an open calorimeter

∆H= qp

Temp measured in a bomb calorimeter is for

Surroundings

If given H°rxn and S°sys, what equation is used

∆H-T∆S

The more negative ∆G

The more stable and down energy hill

In open cup

mC∆T=mC∆T

In bomb calorimeter

mC∆T+C∆T

Molecules in their native state at STP have

standard enthalpy of formation of zero

Specific heat capacity is

amount of heat needed to raise a gram by 1°C

Specific heat capacity is what type of property

intensive

∆H=∆U when

moles on both sides are equal and no work is done

Standard formation of ozone

3/2O2—> O3

Coffee cup calorimeter measure heat at constant

pressure

Bomb cup calorimeter measure heat at constant

volume

For closed calorimeter

∆U=qv