Chem 1A midterm 2

types of degrees of freedom

• rotations

• vibrations

• translations

what do each of the motions relate to?

• more rotations and vibrations = higher specific heat

• translations: only one that increases T

how does heat of the surroundings relate to heat of the system

qsurr = - qsys

when using a calorimeter, how do you find the heat of the surroundings vs. system

• surroundings: qwater = mwater x cwater x Delta T

• system: qsys = -qwater

what is q in exo vs. endothermic reactions

• exo: q<0 (feels HOT)

• endo: q>0 (feels COLD)

how does PE change in exo vs. endo reactions

• exo: high to low PE

• endo: low to high PE

PE for attraction and repulsion

• attraction: low PE

• repulsion: high PE

bond length and strength graph

what type of reaction is bond making

endothermic

only way to release energy w/ bonds

to create a stronger bond

relationship of ΔS-surr to ΔH-sys

ΔS-surr always opposite sign to ΔH-sys

how does entropy relate to changes?

changes occur so that entropy increases

when is a reaction spontaneous

when ΔS>0

when is a reaction favorable?

when ΔG<0

when ΔS>0 and ΔH<0, when is the reaction favorable?

favorable at all T

when ΔS<0 and ΔH<0, when is the reaction favorable?

favorable at low T

when ΔS>0 and ΔH>0, when is the reaction favorable?

favorable at high T

when ΔS<0 and ΔH>0, when is the reaction favorable?

favorable at no T

the two things a system favors

• lower energy

• greater dispersion

what does ΔG° assume?

• occurs at standard conditions

• mixture of reactants and products

• all solutions at 1 M = 1 mol / 1 L

• composition of the equilibrium mixture

when is ΔG=0

at equilibrium

when is E° favorable

when E°>0

In what direction does electron transfer occur

so that ΔG°<0 and E°cell>0 (product favored)

how to know if atom is magnetic

if it has any unpaired electrons in orbital

oxidation

losing electrons

reduction

gaining electrons

ΔG° in redox

who is better at attracting the e^-

E°_cell

= E°_red - E°_ox

cathode

where reduction takes place

anode

where oxidation takes place

how does E° compare in cathode vs. anode

• cathode: higher E°

• anode: lower E°