Test 3 + some final stuff - Chem 112- Summer Flashcards by Alessia Velasquez Nitti

Ksp

solubility equilibrium/solubility product constant, for ionic compounts treated as insoluble typically. Since it is a salt –><– cation + anion, the salt is a solid and is not included in the equilibra

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molar solubility

moles/L of a saturated solution (so its the x in an ICE table or the E)

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solubility

number of grams of solute in 1L of saturated solution

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when Q < Ksp

no precipitate

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when Q > Ksp

precipitate

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Q= Ksp

no precipitate

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factors that affect solubility

common ion effect, pH, formation of complex ions

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common ion effect

suppresses the ionization of an electrolyte when another electrolyte (that contains a common ion) is added

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how does pH affect solubility

solubility increases as the pH decreases (i.e. if you add an acid, the solubility will increase and move forward)

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thermodynamics

the science dealing with heat and the relationship with other forms of energy. thermodynamics can predit whether a process will occur (but it does NOT predict amount of time required for process)

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spontaneous process

occurs without outside intervention under specific set of conditions

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nonspontaneous

does not occur without outside intervention (CONTINUAL input of external energy)

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first law of thermodynamics

any change in internal energy is due to either heat or work (this energy can be kinetic or potential)

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change in U

change in U = q + w

U is change in internal energy. q is heat. w is work.

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thermochemistry

the study of the heat absorbed or released during chemical and physical changes

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what is work

force applied x distance traveled. work involves movement

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enthalpy letter

H,, change in H

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enthapy def

a thermodynamic quantity.

change in H= change in U + P(change in V)

but it is also change in H = q (aka heat)

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exothermic processes tend to be what

spontaneous. BUT this is not guarenteed

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Entropy letter

S,, change in S

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entropy def

entropy is a state function. it is a thermodymanic quantity that measures the amount of disorder in a system. to predict spontainiety, both enthapy and entropy must be known.

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boltzman’s def

measure of disorder. S=KlnW

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as temp increases ENTROPY of a system does what

decreases

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S of different states

S gas > S liquid > S solid

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more microstates = what

higher entropy

K = what

boltzmann's constant (1.38 x 10^-23 J/K)

W= what

microstates (number of diff arrangements)

probabulity distributiion of microstates

W=X^N X= number of cells in a volume N = number of molecules

change in entropy

change in S system= S final- S initial

standard entropy

absolute entropy at 1 atm

# choose one: S increases with (larger/ smaller) molar mass

larger. entropy increases with larger molar mass

S increases with (more/ less) molar complexity

more molar complexity

change in S universe

= change in S system + change in S surroundings

change in S universe > 0

spontaneous

change in S universe < 0

nonspontaneous (spontaneous in reverse reaction)

change in S universe = 0

equilibrium

Second law of thermodynamics

change in S universe stuff

third law of thermodymanics

entropy of a pure perfect crystal substance at 0K is equal to 0. at 0, molecular movement stops. only one way to arrange the molecules at this point. Cannot go lower than 0K

change in S (in relation to other S)

change in S= S products- S reactants

gibbs free energy (def and equation)

measure of available energy. change in entropy is directly porportional to enthaply of a system change in S surrounding = (-change in H system)/T

gibbs free energy more direct equation

change in G = change in H - T (change in S)

change in G < 0

spontaneous in forward

change in G > 0

non spontaneous in forward

change in G = 0

equilibrium

what is G

gibbs free energy (spontaniety)

spontaneous reactions generally have what

change in H < 0 change in S > 0 change in G < 0

for a reaction to be spontaneous in low temp

change in G > 0 for an endothermic raction or change in G < 0 for an exothermic reaction

exothermic reaction means what for change in H

change in H > 0

exothermic reaction means what for change in H

change in H < 0

for a reaction to be spontaneous in high temp

change in G < 0 for endothermic and exothermic

for a reaction to be nonspontaneous in high temp

change in G > 0 for endothermic and exothermic

for a reaction to be nonspontaneous in low temp

change in G> 0 for endothermic or change in G< for exothermic

to find temp at which spontaneity changes when G=0

T= change in H/change in S

standard free energy symbol and def

symbol = change in G degrees def= free energy change for a reaction when it occurs under standard state conditions

when K >1, change in G degrees is what

when K >1= -( change in G degrees)

when K < 1, change in G degrees is what

when K >1= + ( change in G degrees)

when Q < K, change in G degrees is what

negative

when Q > K, change in G degrees is what

positive

addative free energy change

change in G 3= change in G 1 + change in G2

oxidation

loss of electrons

reduction

gaining electrons

reducing reaction

loss electrons

oxidizing agent

gain electrons

hydrogen has what oxidation number

oxygen has what oxidation number

-2

balancing redox reaction steps (acidic)

1. write half reactions 2. balance half reactions 3. balance O by adding H2O 4. balance H by adding H+ 5. balance charge by adding electrons 6. make electrons = 7. add half reactions together

balancing redox reactions (basic)

normal steps + 1. for H+ ions, add on OH- to BOTH sides 2. make additional cancellations of all ner H20 molecules

what are galvanic (voltaic) cells

cells that use spontaneous redox reactions to produce electrical energy

anode

negatively changed metal electrode responsible for oxidation (the oxidation side of reaction)

cathode

positive changed metal electrode responsible for reduction (the reduction side of reaction)

why does current flow and what direction (anode vs cathode)

flows from anode to cathode. does this because there is a difference in electrical potential energy

Ecell

electrical potential/cell potential. measured by voltmeter

cell notation

left side is anode, right is cathode

E degrees=

E cathode - E anode (you will need to look these values up)

E degrees > 0

spontaneous

E degrees < 0

nonspontaneous

redox is spontaneous if (3 things)

1. E degree cell is positive 2. change in G degree is negative 3. K is greater than 1

if E degree is negative, it means what

non spontaneous, so charge is flowing from cathod to anode (reverse direction)

when Q>1, E (< / >) E degrees

Q >1, E < E degrees

when Q< 1, E (< / >) E degrees

Q< 1, E > E degrees

when given numbers, which is the anode and which is cathode

the smaller one is anode, the larger is cathode

for standard cell potential (the change in E degrees) equation, do you need to pay attention to stoichiometry?

no. so DON'T multiply to make them equal.