Acid-Base Equilibria Flashcards by Wandat hahaa

3 AUTHORS who defined Acids and Bases

Arrhenius
Bronsted-Lowry
Lewis

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DEFINITION OF ACIDS AND BASES

What did Arrhenius say?

Acid = [H+] in solution
Base = [OH-] in solution

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DEFINITION OF ACIDS AND BASES

What did Bronsted-Lowry say?

Acid = (H+) donor
Base = (H+) acceptor

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DEFINITION OF ACIDS AND BASES

What did Lewis say?

Acid = e- pair acceptor
Base = e-pair donor

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What is Neutralization Reaction?

acid + base -> salt and water

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net ionic reaction of every neutralization reaction?

H+ (aq) + OH- (aq) -> H2O (l)

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the _____ theory did not hand non-OH- bases( e.g. ammonia) very well

Arrhenius

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are all Bronsted-Lowry acid/bases all arrhenius acid/bases?

No, bc arrhenius requires bases to have an OH-

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is F- an example of a base?

yes because of its negative charge -> can receive a proton

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2 properties of Water

Amphoteric = can be an acid or a base

Amphiprotic = can accept o donate a proton

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Equation Reaction for Water

2H2O (l) -> <- H3O+ (aq) + OH- (aq)

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What is the ION-PRODUCT CONSTANT and its value for water

Kw = [H3O+][OH-]

Kw of water = 1.0 x 10^-14 at 25 C

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is Kw = 1.0 x 10^-14 at 25 C

always constant for water?

what happens if u add acid or base?

yes, its a constant value for water

at pH = 7, the [H+] and [OH-] is equal

– but once u add acid/base, the [H+] and [OH-] start to differ

however, Kw stays constant pa rin (meaning, the total product of [H+] and [OH-] is still equal to Kw)

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FORMULAS for all acid-base equilibria for:

pH
pOH
pKa / pKb
Ka
Kb
Kw (2)
[H3O+]
[OH-]

+ other formulas (2)

1.) pH = -log (H+)

2.) pOH = -log (OH-)

3.) pKa = - log (Ka)
* same with pKb

4.) Ka = [H+][A-] / [HA]

5.) Kb = [OH-][BH+] / [B]

6.) Kw
= (Ka)(Kb)
= [-log (H+)] + [-log (OH-)]

7.) 10^ -pH

8.) 10^ -pOH

OTHER:
pH + pOH = 14
pKa + pKb = 14

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the higher the [H3O+], the ____ the pH

lower

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Do K eq values have a unit? If so, what is it?

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Shortcut in identifying shift of rxn based on acids and bases

If H3O + is a product, find and compare the reactant and product base. Weaker base -> dito ung shift

If OH- is a product, find and compare the reactant and product acid. Weaker acid -> dito ung shift

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SHIFT IN ACID-BASE RXNS

HCl + H2O -> H3O+ + Cl-

H3O+ so compare the bases

RB: H2O
PB: Cl-

HCl is a strong acid so its conjugate base (Cl-) is a very weak base. Thus, the reaction shift is forward, and the formation of H3O+ is favoured

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SHIFT IN ACID-BASE RXNS

CH3COOH + H2O -> <- H3O+ + CH3COO-

H3O+ so compare the bases

RB: H2O
PB: CH3COO-

CH3COOH is not a strong acid so its conjugate base (Cl-) is stronger base compared to water. Thus, the reaction shift is reverse, and the formation of CH3COOH is favoured

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Relationship between Acids and Bases

The stronger the Acid, the weaker the Base

Kaya… every conjugate base of a strong acid is weaker than water

every conjugate acid of a strong base is weaker than water

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Strong Acids Examples (8)

HCl
HBr
HI
HNO3
H2SO4
HClO3
HClO4
Sulfonic Acids

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Strong Bases Examples (9)

Commonly Group 1 & 2 + OH

LiOH
NaOH
KOH
RbOH
CsOH
Ca(OH)2
Sr(OH)2
Ba(OH)2
ammonium hydroxides

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What is the MOST important rule before doing anything?

BALANCE THE EQUATION

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REVIEW!!!

Name the Weak ACIDS/BASES and their conjugates

1.) H2O -> H3O+
2.) H2O -> OH-

Study These Flashcards

1.) Weak Base: H2O ; Conjugate Acid: H3O+
2.) Weak Acid: H2O ; Conjugate Base : OH-

when acids ionize in water, it creates ___ when bases ionize in water, it creates ____ *this is according to the ______ theory

- hydronium ion (H3O+) - hydroxide ion (OH-) **water acts as base and acid respectively *Bronsted-Lowry Theory

when is the ff formed? + based on what theory? 1. conjugate acid 2. conjugate base

BRONSTED-LOWRY THEORY 1. conjugate acid is formed when its base accepts a proton 2. conjugate base is formed when its acid donates a proton

ACC TO THE ____ theory - both the forward and the backward reactions are acid-base reactions *so the rxn equilibrium is composed of 2 acid-base conjugate pair

Bronsted Lowry Theory

SF rules in Logarithmics

The # of SF in argument will become the # of decimal points in final answer

What will be the equation of Ca(OH)2 (aq)?

Ca(OH)2 is a strong base so one arrow will be used + will dissolve into ions Ca(OH)2 -> (w/ H2O) -> Ca2+ + 2OH-

What will be the equation of HCl (aq)?

HCl is a strong acid so one arrow will be used +since acid, H2O (l) will be in reactants side to form H3O+ HCl + H2O (l) -> H3O+ + Cl -

Formula for Kw using Ka and Kb

Kw = (Ka)(Kb)

Relationship of Ka & strength of acid Kb & strength of base

both direct relationship

What should be shown in solution when there is a need to solve for x using quadrating equation?

SHOW: Ax^2 + Bx + C = 0

If pH or pOH is given and we want to fine the value of H3O+ or OH -, WHAT to do?

antilog 10^NEGATIVE pH/pOH

Formula for % ionization

% ionization = (amount dissociated) / (initial concentration) x 100 % ionization = (equilibrium concentration) / (initial concentration) x 100 % ionization = (conjugate/weak acid or base not h2o) x 100

strong acids and bases undergo ________ ionization in water weak acids and bases undergo ______ionization in water

- complete - partial

What are buffers?

Solutions that resist drastic pH changes upon addition of small amounts of acids or bases

Criteria for buffers (3)

1. Weak acid and salt of its conjugate base 2. Weak base and salt of its conjugate acid 3. 1 proton difference

How to know if it's a salt?

No charge since it should form an ionic compound

CH3COOH - NaCH3COO Equilibrium Rxn Buffering Action (Acid) Buffering Action (Base)

Since CH3COOH will donate a proton, it is a weak acid CH3COOH + H2O (l) -><- CH3COO- + H3O+ (aq) addition of ACID: CH3COO- + **H3O+ (aq)** -> CH3COOH + H2O (l) addition of BASE: CH3COOH + **OH- (aq)** -> CH3COO- + H2O (l)

NH3 - NH4Cl Equilibrium Rxn Buffering Action (Acid) Buffering Action (Base)

Since NH3 will receive a proton, it is a weak base NH3 + H2O (l) -><- NH4+ + OH- (aq) addition of ACID: NH3 + **H3O+ (aq) ** -> NH4 + H2O (l) addition of BASE: NH4+ + **OH- (aq) ** -> NH3 + H2O (l)

Are buffering actions complete or partial dissociation?

Complete dissociation

BRONSTED LOWRY THEORY - all notes summary (4)

1. acid - proton donator base - proton receiver 2. acid -> H3O+ base -> OH- 3. rxn equilibrium is composed of 2 acid-base conjugate pairs 4. stronger acid/base -> weaker its conjugate

most general theory among the 3?

Lewis Theory as it includes many reactions that do not involve Bronsted acids (e.g. no transfer of H+ but there is electron transfer)

how to know if a reaction undergoes proton or electron transfer?

proton transfer -> may + charge sa products side electron transfer -> may bond formation AND/OR no + charge sa products side

TYPES OF ACIDS (3) + short definition + increasing trend

1. Binary Acids - H + X - right-down 2. Oxoacids - H+O+X - right-up (as EN increases) 3. Organic Acids

Compare the stabily of their conjugate: - strong acid - weak acid - strong base - weak base

Strong acid → weak conjugate base (stable). Weak acid → strong conjugate base (unstable). Strong base → weak conjugate acid (stable). Weak base → strong conjugate acid (unstable). **the stronger species (acid or base) will always be paired with a more stable conjugate

the stronger the acid, the ____ the bond the stronger the base, the higher its ____ value

- weaker - Electronegative (increasing right-up)

how is the calculation of pH of strong bases and acids DIFFER from calculation of pH of weak acids/bases

STRONG A/B 1. RXN EQ: dissociation matic e.g. Ba(OH)2 -> Ba2+ + 2OH- * special case in HCl +H2O -> H3O+ + Cl- (and other similar strong species) bc our goal is for OH or H3O to show up 2. in ICE table, change is similar to initial concentration of strong a/b bc COMPLETE DISSOC -- WEAK A/B 1. RXN EQ: HA + H2O -> A- + H3O+ B + H2O -> BH+ + OH-

other term for Ka and Kb? + relationship with acid/base strength & pKa/pKb

Ka = acid ionization constant - (higher Ka = higher acid strength = lower pKa) Kb = base ionization constant (higher Kb = higher base strength = lower pKb)

FORMULA FOR: - degree of ionization - % ionization

DOI = [H3O+] eq / [HA]0 = [OH-] eq / [B]0 % ionization = times 100% to above

STRONG ACIDS BASES -- calculating pH - exception?

if the [H3O+] or [OH-] at equilibrium is ≤ 1.00 x 10^-5 then add [H3O+/OH- in water] = 1.00 x 10^-7 before calculating the pH

Determine if which of the ff will hydrolyze in water: 1. Neutral salts (Ka = Kb) 2. Basic salts (Ka < Kb) 3. Acidic salts (Ka>Kb) + why

1. NS: from strong base and acid -> do not hydrolyze in water 2. BS: strong base and weak acid -> conjugate base of weak acid will hydrolyze 3. AS: weak base and strong acid -> conjugate acid of weak base will hydrolyze

2 formulas in Buffers + what do you call this?

Henderson-Hasselback Equation pH = pKa + log [A-] / [HA] pOH = pKb + log [BH+] / [B]

how to select the perfect buffer?

its pKa value should be close to your desired pH

buffer capacity vs buffer range

BUFFER CAPACITY - amount of acid/base that a buffer can neutralize before its pH changes appreciably BUFFER RANGE - pH range over which a buffer effectively neutralizes acids and bases

what is the usual buffer range?

2 pH units around pKa (+- 1)

Acid-Base Equilibria Flashcards

(58 cards)