14B midterm #1 (week1-week3 (eq to acid ba

what are the strong acids

HI, HBr, HCl, HNO3, HClO3, HClO4, H2SO4

what are the strong bases (where on the periodic table are they)

first 3 on the first coloumn and 3-5 on the second coloumn

Li, K, Ba, Ca, Sr, Na

is HF a weak acid or strong acid

weak, the HF bond is strong since F is so small

what are the periods on the periodic coloumn

• Periods run left to right (there are 7 periods).

• The period number = number of occupied electron shells.

  • Period 2 elements have 2 electron shells

• As you move left → right across a period:

  • Atomic number increases

  • Valence electrons increase

  • Metallic character decreases

what are the groups on the periodic table

• Groups run top to bottom (there are 18 groups).

• Elements in the same group have:

  • Same number of valence electrons

  • Similar chemical properties

• Group number (for main-group elements) ≈ number of valence electrons.

Important groups to know:

• Group 1: Alkali metals (Li, Na, K) → 1 valence e⁻, very reactive

• Group 2: Alkaline earth metals (Mg, Ca) → 2 valence e⁻

• Groups 3–12: Transition metals

• Group 17: Halogens (F, Cl) → 7 valence e⁻

• Group 18: Noble gases (Ne, Ar) → full valence shell, very unreactive

what does it mean when the equillibirum constant (K) is equal to one?

It shows that the reaction favors neither products nor reactants

standard unit for Kp and standard unit for Kc

atm and M

When can a equilibirum constant be applied to a reaction Q of a certain reaction?

Where the reaction has the same temperature and stoichiometry as the reaction that derived that K eq constant

in what situations does the K change and in what situations does the Q change

K changes on temperature and stoichiometry of the reaction (basically the identity of the reaction)

Q changes depending on pressure and volume changes and the addition/subtraction of reactant/product

when can you treat the change or (x) as 0 when substracting from the intital concentration

if it is less than 1E10^-4 or less than 5 percent of the intital concentration of the reactant

do you include solids and liquids in the equillbrium constant

no, even if it a solvent we do not include it unless the solution is REALLy concentrated

what is the defintion of le chatliers principle

chemical reactions adjust so as to minimize the effect of any of the changes induced to the environment of the reaction

Why does changing the temperature of a reaction chaneg the equillbirum constant?

-K is derived from delta G (gibbs free energy) which is dependent on temperature

-temp puts a limit to how the reaction proceeds since depending on if the reaction is endo or exothermic, the temperature can influence how much free energy is avalible for that reaction to use

What happens to K as you increase the temperature, decrease the temperature

If it is a exothermic reaction:

Increasing temperature: favors the reactants, K is smaller

decreasing temperature: favors the products, K is larger

If it is a endothermic reaction:

Increasing temperature: favors the products, K is larger

decreasing tempertaure: favors the reactants, K is smaller

Do catalysts and changing collision frequency of gas moelcuels influence either Q or K?

no, it changes the rate of reaction but not the equillibirum states or the concentrations, only influences how fast the reaction proceeds

How does an increase and decrease in volume influence the Q (only applicable to gases)

Increasing volume; the Q shifts towards the side with more moles

Decreasing volume: the Q shifts towards the side with less moles

How does an increase and decrease in pressure influence the Q (only applicable to gases)

Increasing pressure; the Q shifts towards the side with less moles

Decreasing pressure: the Q shifts towards the side with more moles

-all functions because the change in pressure causes a chaneg in volume which leads to a change in concentration thus effecting the Q

what does it mean when a shifted to the products or shifted to the reactants in response to a change in environment; and relate it to the difference between Q and K

when a reaction has an increase in pressure and shifts to the side with less moles, this is because the pressure changes Q, making Q not equal to K anymore and then the reaction is said to shift in goal of making Q=K;

when the Q shifts to one side of the reaction due to environment changes, the reaction “does” this to achieve what

it does this to achieve K

what does it mean when a reaction is product favored or reactant favored

Product-favored (leans to the right)

• At equilibrium, mostly products are present.

• The equilibrium constant is large

Reactant-favored (leans to the left)

• At equilibrium, mostly reactants are present.

• The equilibrium constant is small

what does the addition of inert gas do to a reaction

increases pressure of the system but does not influence Q and K because it does not create a change in volume

what would increasing or decreasing the concentrations of solids and liquids do to the Q and K

it would not affect equillbrium or change the state of equillbrium (not make the reaction shift left or right) this is because it is not included in the reaction quotient or equillbirum equation; but it could slow or speed up the rate of reaction due to availibility

Pure solids and pure liquids have constant activity:1 so omitted

-can control how far a reaction goes but not equillbrium state;

the equilibrium expression does not change

• The value of K does not change

• The system simply cannot satisfy Q=K anymore; breaks equillbirum

what is the default K for gaseous reactions

Kp derived from PP

spectator ions do not participate in a equillbirum equation, they get canceled out

ff

what does the delta G or gibbs free energy of the reaction equal to when equillbirum is reached; what equation proves this

delta G equals 0, this is because the equation for delta G= deltaGknot + RTlnQ where delta Gknot is -RTlnK

when delta G knot of a reaction is negative and positive what does that mean for K

if positive then K is reactant favored (small K)

if negative then K is product favored (large K)

what should you do to K for the opposite reaction

take the inverse of K (1/K)

what should you do for K if the reaction is multiplied by a constant

K^constant

assume that K value for tables of gas reactions is in Kp, thus you will need to convert to Kc because Kp does not equal Kc; what is the equation for this conversion

Kp=(RT)^delta n times Kc

delta n= nprod- nreact

the (not delta) total G of the reaction is at_____ when it reaches equillbrium state

minimum energy

Geq must always be ____ than Gintital/Greactionatthatpoint for a reaction to be spontaneous

less than; so that the reaction moves towards a state of reaction (how much product and reactant being formed) that will reach that Geq minimum

explain all parts of the delta G=delta Gknot + RTlnQ

delta G tells us which way the reaction is heading in order to reach equillbirum (where delta G equals zero)

therefore: if delta G is greater than zero moving towards the reactants lowers total G and would be making G head towards the minimum and if delta G is less than zero moving towards the products would lower total G

RTlnQ encodes for the current composition of the reaction (is not constant, changes)

delta G knot: tells us what the minimum delta G is (therefore eq is reached when rtlnQ reaches this minimum) and delta G=0

relationship with equillbrium and slope when delta G= Gprod-Greactants

when the slope is zero, equillbrium is reached,

When we plot total Gibbs free energy G vs extent of reaction

• Left side: mostly reactants

• Right side: mostly products

• Every point on the curve corresponds to a mixture with a specific composition

So:

• The curve is continuous

• Reactants and products are not just two isolated points

2. What “slope = 0” really means

At equilibrium:

• The tangent line to the curve at that point is horizontal

• That point is a minimum of the curve

what does delta G equal

Gproducts-Greactants (NOT FINAL MINUS INTIAL)

what is delta G knot under standard conditions and what is K

delta G knot is zero, K is 1

what does dynamic equillbrium mean

the forward and backward reaction are occuring at the same rate

what does the difference of Q from K tell us about reaction rates (REMEMBER THAT THIS IS DIFFERENT FROM absolute speeds)

The difference between QQQ and KKK determines which reaction rate is larger and by how much, with the magnitude of K/QK/QK/Q indicating how strongly the system is driven toward equilibrium.

What the difference between Q and K tells you Direction of net reaction

• Q<K → forward rate > reverse rate → net forward reaction

• Q>K → reverse rate > forward rate → net reverse reaction

• Q=K → forward rate = reverse rate → equilibrium

How unequal the rates are (how far apart from eachother)

The farther Q is from K:

• The more unequal the forward and reverse rates

• The stronger the “driving force” toward equilibrium

delta G tells us

the direction of the reaction to reach eq not the speed

if the temperature for the problem is not given then assume…

the reaction is at RT (25 degrees)

equillibrium state favors stability; the ratio of product to reactant is where the reaction is at the most ___ energy and the stable state at soecific temp

low

it does not matter if you add product or reactant first, the direction of the reaction may change but the equillbrium does not

bb

homogenous equillbrium

when the reactants and products are all in the same phase

before calculating Kp, convert all pressures to what unit

Atm

equation to convert PP to conc and conc to PP

PP= [M]xRxT

if K is between 10^-3 and 10³ then the reaction is said to be

neither strongly favord in products or reactants

how is pressure for a gas defined

Pressure = force exerted/area over which the force is exerted

where does the pressure of a gas stem from

-the molecular collisions between gas particles

-the stronger and more collisions, the greater the forces and pressure

molar volume (Vm) what are the 2 equations

(volume occupied by gas) / (number of moles of the gas)

RT/P

the amount of volume a mole of gas occupies; under STP it is 22L/mol

what is an ideal gas

An ideal gas consists of point particles with negligible volume, no intermolecular forces, and perfectly elastic collisions, so its behavior is fully described by PV=nRT

Core assumptions (memorize these)

1. Particles have no volume
   The volume of the gas particles themselves is negligible compared to the container.

2. No intermolecular forces (IMFs)
   No attractions or repulsions between particles except during collisions.

3. Perfectly elastic collisions
   Total kinetic energy is conserved in all collisions (particle–particle and particle–wall).

4. Random, continuous motion
   Particles move randomly in straight lines between collisions.

partial pressures and daltons law

the sum of the partial pressures is the total mixture ofgases

-a Partial pressure: the pressure that a gas in a mixture would exert if it alone occupired the container

-think that the gases a and B are independently colliding of eachother on the walls of the vvessel

-daltons law is based off the assumption that the collisions are independent of eachother

equation for partial pressures and total pressure

xApA + xBpB …. = total pressure

xA: mole fraction of A; moles of A/total moles of gases

the combined gas law

p1v1/n1t1 =p2v2/n2t2 where 1 indicates initial and 2 indicates initial

molar concentration of gas

1/Vm (molar volume)

mass density of a ideal gas

mass/vol

d=(MM)P/RT where MM is molar mass the gas

molar concentration and density of a gas is dependent on

Temperature and pressure: when they increase the conc and den increase

when they decrease the conc and den increase

autoproteolysis

the process by which 2 h2o molecules form h3o and oh-

the autoproteolysis constant: [h3o+][oh-]

does the autoproteolysis constant always equal 1e10^-14

no, autoproteolysis constant increases as temperature increases (therefore the constant decreases as temperature decreases) since the reaction is endothermic, thus as temperature increases ph decreases while poh increases, still maintaing how ph+poh=14

-at these new temperatures, ka times kb still equals kw, just the new kw at that temperature

what is the ph of a corrosive substance defined as

if the ph is lower than or equal to 1.5 or higher than 11.5

do strong acids and bases have ka and kb

no, the reaction goes so close to completion in the product side that the Ka or Kb would be large; there would be nothing in the denominator of the equation

what is the base and acid form of strong acids and storng bases

h3o+ for acids and oh- for bases

the stronger the conjugate base s the weaker the

acid

what does it mean when a strong acid or base is said to “level” water

the observation that strong acids and bases all have the same strength. in h2o

explain why the addition of a strong base or acid shifts autoproteolysis so that Kw is still 1e10^-14 @ 25C

-the acid or base form of a strong base/acid (in the form of oh- or h3o+) contributes to the equillbrium constant for the autoproteolysis of water, thus since only one of the concentrations of either oh or h3o goes up, there is too much of product on the autoproteolysis side which lowers the production of whatever was not contirbuted by the strong acid/base

explain why KaxKb (of a weak acid or weak base) equals Kw and why we do not account for the [oh-] and [h3o+] from autoproteolysis

the equillbirum constant equation for the ka and kb cancel out to form the equation for kw, and we do not account for the oh- and h3o+ from autoproteolysis since the concentration is so low in comparison to what the weak acid and its conjugate contirbutes to the aqueous solution

why and when do we not account for the h3o or oh- created by autoproteolysis when calculating for [h3o+] when a strong acid or base is added to water

we do not account for the h3o and oh- because in comparison to the amounts contirbuted by the strong acid or base, it becomes neglible to account for the addition of that; i.e if the concentration of strong acid is smaller than 1e10^-7 then you must calculate h3o+ by [h3o+x][x]=1e1^-14 the x is the same since autoproteolysis creates equal moles of oh and h3o

percent protonation or deprotonation

protonation; [conjugate acid]/[intial base] x 100

deprotonation; [conjgate base]/[intital acid] x 100

what is a salt (what is the ph of a solution that creates a salt +h2o?)

a ionic compound produced by the neutralization of a base by an acid

-a salt being produced does not mean that the ph equals 7, the ph of the resulting solution depends on the conjugate activity of the base and acid

-thus, if the neutralization occurs by the addition of a strong base to a strong acid then the ph would be 7 (assuming they are added in equal amounts) since their conjugates do not have any acid/base activity

when a weak acid and strong base/ weak base and strong acid neutralize eachother what does this look like

the weak acid or base undergoes full dissociation and remains only of its conjugate, creating water with the fully dissaccoiated oh- or h3o+ of the strong aid/base; then the ph determinate is baesd off the activity of the conjugate of that weak acid/nbase after neutralization

-the reaction for this is denoted as a SINGLE SIDED ARROW

-this is because the h3o and oh- nature of the strong acids and bases pulls so strongly since the Kw constant is so small; showing high favoribiltiy for the formation of h2o

Why does a strong acid fully neturalize a weak base

-this is because the h3o and oh- nature of the strong acids and bases pulls so strongly since the Kw constant is so small; showing high favoribiltiy for the formation of h2o

what does the ph of a neutralization reaction depend on

(most to least)

1.stoich; the relative starting amounts of the acid and base

2.the reatctivrty of the conjugates with water

what is the charge of conjugate acids

cations

types of conjugate acids

-conjugate acids that gained a h or proton

-small highly charged neutral cations

how do small highly charged cations function as conjugate acids (what form is it when functioning as acid)

-when the cation is hydrated with water molecules, it functions as a lewis acid

-the coordinate covalent bond between metallic cation and water molecles weaken the o-h bond on the water molecules, allowing donation of protons

-the cation acts as a lewis acid while the h2o molecules are the lewis base (like a bronsted aciid and base pair) but without a physical transfer of h+

what types of cations are lewis acids

-cations that ARE NOT GROUP 1 AND 2 AND CHARGE OF +1

-must be small and highly charged

lewis acid and lewis base

-a lewis acid is a species that accepts an electron pair

-lewis base is the species that donates one, gaining a “proton”

what is the charge of conjugate bases

anions

if a conjugate of a weak acid has a hydrogen, does that mean that it automatically functions as a acid (like a polyprotic)

-no, the only polyprotics that still have acidic/signifcant acid activity even after being deprotonated once is..

1.HSO4-

2.H2PO4-

(basically the strong acids)

why does the acid charecter of a polyprotic acid decrease as it gets deprotonated

-the Ka of the deprotonated polyprotic already has a h3o+ form the first deprotonation

-the negative charge on the molecule makes it hard to donate/let go of the proton; it is ENERGETICALLY UNFAVORABLE FOR A PROTON TO LEAVE A NEG CHARGED ION

how do you determine the ph of a salt solution that includes the conjugates of a weak acid and base

-determine ka and kb of the conjugates

-set up ice tables for each to determine how much h3o and oh they contribute

-to determine h3o concentration for ph, subtract the amount of h3o contributed by the conjugate acid by the amount of oh- contributed by the conjugate base

-if there is more oh than h3o and h3o gives a neg conc, then calculate reverse (oh-h3o instead of h3o-oh) and find poh then find ph by 14-poh

-if the h30-oh =0, then they fully neutralize, making ph=7 the h3o and oh just ome from the autoionization of water

-when we subtract we are showing that there is no more of the oh or h3o contirbuted by the aicd/base and you are accounting for the oh or h3o created by autoionization

when we add a weak acid and base in water what happens and what matters

-the weak acid and base neutralize eachother if added in equal concentrations; all of the orig acid and base become salt and water

-to ph calculate, compare conjugates and solve

-we do not need to consider the reactions of these weak acid and bases with water because the equillbrium constant for its reaction with eachother in forming the salt is the simplified version of their individual reactions with water

-even if the weak acid and base are considered weak, they still undero full proton transfer since weak is relative to its reactivity with water

remember that the fromation of h2o in autoproteolysis is HIGHLY favorable; 10^14 while h3o and oh are not

f

autoproteolysis is specifically waters transfer of protons while autoionization is a broader term

n

polyprotic acid and polyprotic base

a compound that can donate more than one proton; base is any species that can accept more than on proton

After each loss of a proton, the acidity constant (pKa) of the acid gets___

Weaker

What is the only polyprotic acid where we consider the pka2 over pka1

-h2so4, the dissaccociation of the first hydrogen goes to completion: thus due to the one sided arrow, the resulting acidity constant, hso4- can function ONLY as a weak acid (not a conjugate base of h2so4)

When calculating the ph of non strong polyprotic acid, you should onky consider…

-only consider the first pka and its contributions of total h30

-treat solution as a solution of a weak monoprotic acid

-

You must account for the full deprotonation of the h2so4 when calculating the ph of the final solution that contains mostly only hso4

Bb

when determining to consider the second protonation/ to even state that the second acid protonates, pka must be ____ than ph or ka must be ____ than [h3o+]

Higher, lower

Why do we not consider the second protonation for the ph of a solution where the pka of the secondary acid is larger than the ph after the first protonation

Le chatliers principle (due to the high h3o contributed by the first deprotonation and the low pka of the secondary acid, its better for the secondary acid to not deprotonate so that the denominator remains large enough)

When you are comparing the ph and pka or ka and the [h30] the ph and h30 what is the state of the ph and h30

The ph and h30 concentration after the first deprotonation

when the concentration of deprotonated to protonates is equal to one what does this mean for the ph and pka/ poh and pkb

the ph=pka and poh=pkb