Chemistry Final Exam

Enthalpy

Enthalpy

delta H, affected heat, release, gained

Entropy

delta s, measure of disorder or chaos

Equal

heat gain is _______ heat lost

Break

energy needed to _______ bonds

released

Energy __________ to form bonds

0.00

delta H must equal ______ for any element

-delta H

exothermic, heat is released favorable

• delta H

endothermic, heat is absorbed unfavorable

Delta S universe

delta S system + delta S surroundings

delta S surroundings

-delta H/T

• delta S

unfavorable, nonspontaneous

• delta S

favorable spontaneous

negative

products always _______ when forming bonds

Fusion

melting, exothermic

Vaporization

boiling, endothermic

Sublimation

solid to gas, endothermic

Deposition

gas to solid (exothermic)

Gibbs free energy

ΔG = ΔH - TΔS

k>1

______ when delta G < 0 because products are favored

thermodynamically favorable

spontaneous reaction delta H < 0 and delta S > 0

Low Temps

-delta H, -delta S

High Temps

+delta H, +delta H

False

[ ] are equal

True

Rates are equal

Keq, Kc, Kp

rxn @ equilibrium and constant temp, Products/Reactants, no units, Only gases only changed by temp

Inverse

1/Keq

Doubling

[Keq]^2

Forward

Products have higher concentration, Keq > 1

Reverse

Reactants have higher concentration, Keq < 1

Q

reaction quotient, all cases not equilibrium

Equilibrium

A reaction will always shift toward

k > Q

more reactants, shift right, [R] down [P] up

K < Q

more products, shift left [R] up [P] down

Molarity or Pressure

Ice tables always stand for

I

initial molarity

C

Change

E

equilibrium

5% rule

x/initial [ ] * 100

Soluble

Compounds with Group 1 metals

Soluble

NH4+ Ammonia

Soluble

NO3-

Molar Solubility

the number of moles of solute in 1 L of a saturated solution (mol/L)

Soluble

Larger Ksp

Insoluble

Smaller Ksp

Q < Ksp

unsaturated more salt will dissolve

Q = Ksp

saturated, equilibrium

Q > Ksp

supersaturated solution, precipitate will form

Pressure Changes

Higher gas moles creates higher pressure, rxn shifts in opposite of the pressure change

Increased Pressure

rxn shifts towards fewer moles of gas

Decreased Pressure

ran shifts towards more moles of gas

• H

forward with increased temp, increased Keq

• H

Forward with decreased temp, increased Keq

precipitate

Ions with smaller Ksp _____ first

• H

More favorable process

Entropy

A measure of disorder or randomness, + H more favorable, substances always tend towards randomness

Dissolution

the driving force behind ______ is Entropy

Delta G

delta H - T delta S

Rxn occurs

-delta H and positive delta S creates - delta G

Rxn doesn't occur

+delta H and Positive delta S creates + delta G

• delta S

dissolution is always

Endo

Heat + R --> P

Exo

R ---> P + heat

Collision Theory

For a reaction to occur, the particles must collide, they must collide with the appropriate orientation, and they must collide with sufficient energy.

Increased Concentration

Faster reaction rate, increases molecules and increases collisions

Increased Temperature

Faster reaction rate, greater pressure so more collisions

Increased Pressure

Faster reaction rate from more collisions and a greater surface area

Increased Surface Area

Faster reaction rate from more collisions

Catalysts

Faster reaction rate by creating new pathways or elementary steps and doesn't change

Rate= ∆[ ]/∆t

Rate Equation

Relative Rate

Balanced Equation provides...

K

Constant

reactants

The rate law is written as a function of [ ] of all

0 order

rate is always constant, [A]t = -kt + [A]0 Concentration over time is the linear graph

1st order

rate is doubled when [A] is doubled, power of 1, ln[A]t = -kt + ln[A]0, ln concentration over time is linear

2nd order

rate is quadrupled when [A] is doubled, power of 2, 1/[A]t = -kt + 1/[A]0

M-¹(overall -1) * time-¹

Units

Half Life

t 1/2 the time required for the concentration of a reactant to decrease to one half of the original concentration

1st order

A constant half life can be justification for determining

Swamping

one reactant doesn't change and is high in excess.

0.693/k

1st order half life equation

Reaction Mechanisms

Must match balanced equation of reaction and match experimentally rate laws

Slow

rate law determined from ______ elementary step

[Reactants] or Catalysts

Rate law can only contain

∆H positive

endothermic

∆H negative

exothermic

Slow Steps

have a higher bump or highest Activation energy

Two bumps

Two step equation graphs into

Empirical Formula

1.) find mass % 2.) Convert to g 3.) Convert to moles 4.) divide by smallest mole, repeat for each element of compound

Molecular Fomula

1.) DIvide Molar mass of compound by empirical molar mass 2.) multiply equation by whole number

Percent Composition

the mass % of each element in compound, covert % to moles from grams

conductivity

how many mobile ions are present, if there are ions present

Dilution Equation

M1V1=M2V2

Ideal Gas Law

PV=nRT

P and V

Inverse p1V1=P2V2

P and T

Direct P1/T1 = P2/T2

V and T

Direct V1/T1 = V2/T2

Synthesis

A+B-->AB

Decomposition

AB->A+B

Single Replacement

A + BC --> B + AC

Double Replacement

AB + CD = AD + CB