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Acids, Bases and Salts Acids, Bases and Salts

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Acid and BasesAcid and Bases

Acid and BasesAcid and Bases

Naming of Acids• H+ and a nonmetal

hydro (nonmetal) -ide + ic acid

HCl (aq) = hydrochloric acid• H+ & a polyatomic ion.

(polyatomic ion) -ate +ic acid

• HNO3 (aq) = nitric acid

(polyatomic ion) -ide +ic acid

• HCN (aq) = cyanic acid (polyatomic ion) -ite +ous acid

• HNO2 (aq) = nitrous acid

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Acid Properties• taste sour • change the color of litmus from blue to red. blue

to red a-cid.• react with:

– metals such as Zn & Mg (lower on activity series)to produce H2 gas & a salt

– hydroxide bases to produce water and an ionic compound (salt)

– carbonates to produce carbon dioxide.HCl + CaCO3 CaCl2 + CO2 + H2O

These properties are due to the release of hydrogen ions, H+, in water solution.

Formula Writing of Acids: Review

• Write the H+1 first, then figure out what the negative ion is based on the name. Cancel out the charges to write the formula. Don’t forget the (aq) after it…it’s only an acid if it’s in water!

• Hydrosulfuric acid: H+1 and S-2 = H2S (aq)

• Carbonic acid: H+1 and CO3-2 = H2CO3 (aq)

• Chlorous acid: H+1 and ClO2-1 = HClO2 (aq)

• Hydrobromic acid: H+1 and Br-1 = HBr (aq)

• Hypochlorous acid:

• Perchloric acid:

Some Common Bases

NaOHNaOH sodium hydroxidesodium hydroxide lyelye

KOHKOH potassium hydroxidepotassium hydroxide liquid soapliquid soap

Ba(OH)Ba(OH)22 barium hydroxidebarium hydroxide stabilizer for plasticsstabilizer for plastics

Mg(OH)Mg(OH)22 magnesium hydroxidemagnesium hydroxide “MOM” Milk of magnesia“MOM” Milk of magnesia

Al(OH)Al(OH)33 aluminum hydroxidealuminum hydroxide Maalox (antacid)Maalox (antacid)

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Base Properties• Produce OH- in water

• bitter or chalky taste

• a slippery, soapy feeling: react with fats to form soap & glycerol (glycerine).

• change litmus red to blue: “basic blue”

• interact with acids (neutralize acids).

• Form when group I & II metals react with water. The word alkali & alkaline means basic.

Naming of Bases• Bases are named like any ionic compound, the

name of the metal ion first (with a Roman numeral if necessary) followed by “hydroxide”.

Fe(OH)2 (aq) = iron (II) hydroxide

Fe(OH)3 (aq) = iron (III) hydroxide

Al(OH)3 (aq) = aluminum hydroxide

NH3 (aq) is the same thing as NH4OH:

NH3 + H2O NH4OH

Also called ammonium hydroxide.

Formula Writing of Bases• Formula writing of bases is the same as for any ionic

formula writing. The charges of the ions have to cancel out.

• Calcium hydroxide = Ca+2 and OH-1 = Ca(OH)2 (aq)

• Potassium hydroxide = K+1 and OH-1 = KOH (aq)

• Lead (II) hydroxide = Pb+2 and OH-1 = Pb(OH)2 (aq)

• Lead (IV) hydroxide = Pb+4 and OH-1 = Pb(OH)4 (aq)

• Lithium hydroxide =

• Copper (II) hydroxide =

• Magnesium hydroxide =

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Arrhenius Acid/Base Definition

Svante Arrhenius(1859-1927)was a Swedish scientist

An Acid is a hydrogen-containing substance that dissociates to produce hydrogen ions (or hydronium ions , H3O +) in water.”

An Arrhenius base is a hydroxide-containing substance that dissociates to produce hydroxide ions in aqueous solution.

HA → H+ + A-

MOH → M+(aq) + OH-(aq)

Arrhenius acid is a substance that produces H+ (H3O+) in water

Arrhenius base is a substance that produces OH- in water

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Bronsted and Lowry Definition• J.N. Bronsted (1897-1947) and T. M. Lowry (1847-1936) advanced theory of acids and

bases.

Acids – proton donor

Bases – proton acceptor

A “proton” is really just a hydrogen atom that has lost it’s electron!

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HCl (aq) + H2O(l) → H3O+(aq) + Cl-(aq)

proton acceptorBronsted-Lowry Baseproton donorBronsted-Lowry Acid

A Brønsted-Lowry acid is a proton donorA Brønsted-Lowry base is a proton acceptor

acidconjugate

basebase conjugate

acid

Conjugate acid-base pairs differ by a single proton.

ACID-BASE THEORIESACID-BASE THEORIESACID-BASE THEORIESACID-BASE THEORIES

The Brønsted definition means NHThe Brønsted definition means NH33 is is

a a BASEBASE in water — and water is in water — and water is itself an itself an ACIDACID

BaseAcidAcidBaseNH4

+ + OH-NH3 + H2OBaseAcidAcidBase

NH4+ + OH-NH3 + H2O

Conjugate PairsConjugate Pairs

Label the acid, base, conjugate acid, and Label the acid, base, conjugate acid, and conjugate base in each reaction:conjugate base in each reaction:

HCl + OHHCl + OH--   Cl   Cl-- + H + H22OO HCl + OHHCl + OH--   Cl   Cl-- + H + H22OO

HH22O + HO + H22SOSO44   HSO   HSO44-- + H + H33OO

++ HH22O + HO + H22SOSO44   HSO   HSO44-- + H + H33OO

++

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1. Are sulphate and sulfuric acid conjugate acid and base of each other? Why or why not?

2. Write conjugate base of H3PO4.

3. Write conjugate acid of NO3-

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Lewis Acids and Bases

• G. N. Lewis (1923) developed a more comprehensive theory of acids and bases.

• Deals with the way in which a substance with an unshared pair of electrons reacts in an acid-base type of reaction.

Lewis Acids & BasesLewis Acids & Bases

Lewis acid - a substance Lewis acid - a substance that accepts an electron that accepts an electron pair ( has a vacant orbital)pair ( has a vacant orbital)

Lewis base - a substance Lewis base - a substance that donates an electron that donates an electron pairpair

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Lewis AcidElectron Pair Acceptor

Lewis BaseElectron Pair Donor

Electron pair donated to H+

Species that act as Lewis basesSpecies that act as Lewis bases are alsoare alsoB-L bases (can accept H+).B-L bases (can accept H+).Lewis acids need not be B-L Lewis acids need not be B-L acids ,broadens definition of acid.acids ,broadens definition of acid.

Formation of hydronium ion is also an excellent Formation of hydronium ion is also an excellent example.example.

Lewis Acids & BasesLewis Acids & Bases

•Electron pair of the new O-H bond Electron pair of the new O-H bond originates on the Lewis base.originates on the Lewis base.

HH

H

BASE

••••••

O—HO—H

H+

ACID

Lewis Acid-Base Lewis Acid-Base Interactions in BiologyInteractions in Biology

• The heme group in The heme group in hemoglobin can hemoglobin can interact with Ointeract with O22 and and

CO.CO.• The Fe ion in The Fe ion in

hemoglobin is a hemoglobin is a Lewis acidLewis acid

• OO22 and CO can act and CO can act

as Lewis basesas Lewis basesHeme group

Identify the lewis acid &base• Ni2+ + 6NH3 Ni(NH3)6

• Cation can accept electrons

• Nitrogen has lone pair

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Strong and Weak Strong and Weak Acids/BasesAcids/Bases

The strength of an acid (or base) is determined by the amount of IONIZATION.

The strength of an acid (or base) is determined by the amount of IONIZATION.

Acids and bases are generally divided into STRONG or WEAK Acids and bases are generally divided into STRONG or WEAK onesones..

Strong and Weak Acids/BasesStrong and Weak Acids/BasesSTRONG ACID: HNOSTRONG ACID: HNO3 3 (aq) + H(aq) + H22O (l) --->O (l) --->

HH33OO+ + (aq) + NO(aq) + NO33- - (aq)(aq)

HNOHNO33 is about 100% dissociated in water. is about 100% dissociated in water.

Weak acids are much less than 100% ionized in water.Weak acids are much less than 100% ionized in water.One of the best known is acetic acid, CHOne of the best known is acetic acid, CH33COCO22HH

• Strong Base:Strong Base: 100% dissociated in water. 100% dissociated in water.

NaOH (aq) ---> NaNaOH (aq) ---> Na+ + (aq) + OH(aq) + OH- - (aq)(aq)

Strong and Weak Strong and Weak Acids/BasesAcids/Bases

Other common strong bases Other common strong bases include KOH and Ca(OH)include KOH and Ca(OH)22..

CaO + HCaO + H22O -->O -->Ca(OH)Ca(OH)22

CaOCaO

• Weak base:Weak base: less than 100% ionized in water less than 100% ionized in water

One of the best known weak bases is One of the best known weak bases is ammoniaammonia

NHNH3 3 (aq) + H(aq) + H22O(l) O(l) NHNH44+ + (aq) + OH(aq) + OH- -

(aq)(aq)

Strong and Weak Strong and Weak Acids/BasesAcids/Bases

Strong and Weak Strong and Weak Acids/BasesAcids/Bases

Weak BasesWeak Bases

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A strong acid has a weak conjugate base & vice versa.

List of strong Acids: HCl, HNO3, H2SO4, HI, HBr,, HClO4

List of Strong Bases: group 1 metals (except Fr) and Sr, Ba, Ca hydroxides ( remember solubility rules)

Monoprotic Acids: Have one proton that can be donated. Ex. HCl, HNO3, H C2H3O2

Diprotic Acids: Have two protons that can be donated. H2SO4

Polyprotic Acids: Have more than two protons that can be donated. Ex. H3PO4

Strong vs Weak AcidsIonize completely, forming H+ ions & anions.

HCl (aq) H+ (aq) + Cl- (aq)

In 0.1 mol of HCl in water, there is 0.1 mol of H+ ions, 0.1 mol Cl- ions & no HCl.

All acids that are not strong acids are weak acids: only partially ionized to H+ ions in water.

HF (aq) H+ (aq) + F- (aq) ( double arrow means does not go to completion)

In 0.1 mol of HF in water, there is 0.01 mol of H + ions, 0.01 mol of F- ions & 0.09 mol of HF molecules.

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HBr(aq) + KOH(aq) → KBr(aq) + H2O(l)

Reaction with Bases The reaction of an acid with a base is called a neutralization reaction. In an aqueous solution the products are a salt and water:

2HNO3(aq) + Ca(OH)2(aq) → Ca(NO3)2(aq) + 2H2O(l)

acid base salt

acid base salt

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titration: The process of measuring the volume of one reagent required to react with a measured mass or volume of another reagent.

TitrationTitrationTitrationTitration

1. 1. Add solution from the buret.Add solution from the buret.2. Reagent (base) reacts with 2. Reagent (base) reacts with

compound (acid) in solution compound (acid) in solution in the flask.in the flask.

3.3. Indicator shows when exact Indicator shows when exact stoichiometric reaction has stoichiometric reaction has occurred. (Acid = Base)occurred. (Acid = Base)

This is called This is called NEUTRALIZATION.NEUTRALIZATION.

Setup for titrating an acid with a baseSetup for titrating an acid with a base

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42.00 mL of 0.150 M NaOH solution is required to neutralize 50.00 mL of hydrochloric acid solution. What is the molarity of the acid solution?

The equation for the reaction is

molMolarity =

L

HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) acid base salt

Convert mL of NaOH to liters of NaOH

The unit of volume when using molarity is liters.

Calculate the moles of NaOH that react.

0.150 mol NaOH0.004200 L = 0.00630 mol NaOH

1L

1 L42.00 mL = 0.04200 L

1000 mL

Calculate the liters of NaOH that react.

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42.00 mL of 0.150 M NaOH solution is required to neutralize 50.00 mL of hydrochloric acid solution. What is the molarity of the acid solution?

The equation for the reaction is

HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) acid base salt

The mole ratio of HCl to NaOH is 1:1The moles of NaOH that react equals the moles of HCl that react.

0.000630 mol NaOH react.

0.000630 mol HCl react.

molM = =

L

0.0630 mol HCl

0.05000 L

The molarity of the HCl solution is

.0126 M

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(H+ + Cl-) + (K+ + OH-) → K+ + Cl- + H2O

In the total ionic equation all ions present in solution are written.

H+(aq) + OH-(aq) → H2O(l)

In the net ionic equation only the ions that react are written.

HCl(aq) + KOH(aq) → KCl(aq) + H2O(l) acid base salt

In the un-ionized equation all compounds are written using their molecular or formula expressions.

K+ ion does not react.Cl- ion does not react.Ions that do not participate in a chemical reaction are called spectator ions.

35.62 mL of NaOH is 35.62 mL of NaOH is

neutralized with 25.2 mL of neutralized with 25.2 mL of

0.0998 M HCl by titration to an 0.0998 M HCl by titration to an

equivalence point. What is the equivalence point. What is the

concentration of the NaOH? concentration of the NaOH?

LAB PROBLEM #1: Standardize a solution LAB PROBLEM #1: Standardize a solution of NaOH — i.e., accurately determine its of NaOH — i.e., accurately determine its concentration.concentration.

LAB PROBLEM #1: Standardize a solution LAB PROBLEM #1: Standardize a solution of NaOH — i.e., accurately determine its of NaOH — i.e., accurately determine its concentration.concentration.

PROBLEM: You have 50.0 mL of 3.0 M NaOH PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you and you want 0.50 M NaOH. What do you do?do?

PROBLEM: You have 50.0 mL of 3.0 M NaOH PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you and you want 0.50 M NaOH. What do you do?do?

3.0 M NaOH 0.50 M NaOH

H2O

Concentrated Dilute

Dilute the solution. But how Dilute the solution. But how much water do we add?much water do we add?

PROBLEM: You have 50.0 mL of 3.0 M NaOH PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you and you want 0.50 M NaOH. What do you dodo??

PROBLEM: You have 50.0 mL of 3.0 M NaOH PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you and you want 0.50 M NaOH. What do you dodo??

How much water is added?How much water is added?

The important point is that --->The important point is that --->

moles of NaOH in ORIGINAL solution = moles of NaOH in ORIGINAL solution = moles of NaOH in FINAL solutionmoles of NaOH in FINAL solution

moles of NaOH in ORIGINAL solution = moles of NaOH in ORIGINAL solution = moles of NaOH in FINAL solution moles of NaOH in FINAL solution

moles of NaOH in ORIGINAL solution = moles of NaOH in ORIGINAL solution = moles of NaOH in FINAL solution moles of NaOH in FINAL solution

Amount of NaOH in original solution = M • V = Amount of NaOH in original solution = M • V = (3.0 mol/L)(0.050 L) = 0.15 mol NaOH(3.0 mol/L)(0.050 L) = 0.15 mol NaOH

Amount of NaOH in final solution must also = 0.15 Amount of NaOH in final solution must also = 0.15 mol NaOHmol NaOH

Volume of final solution =Volume of final solution =

(0.15 mol NaOH) / (0.50 M) = 0.30 L or 300 mL(0.15 mol NaOH) / (0.50 M) = 0.30 L or 300 mL

MM11 • V • V11 = M = M22 • V • V22

The pH scale is a way of The pH scale is a way of expressing the strength of acids expressing the strength of acids and bases. Instead of using and bases. Instead of using very small numbers, we just use very small numbers, we just use the NEGATIVE power of 10 on the NEGATIVE power of 10 on the Molarity of the Hthe Molarity of the H++ (or OH (or OH--) ) ion.ion.

Under 7 = acidUnder 7 = acid 7 = neutral 7 = neutral

Over 7 = baseOver 7 = base

pH

• A change of 1 in pH is a tenfold increase in acid or base strength.

• A pH of 4 is 10 times more acidic than a pH of 5.• A pH of 12 is 100 times more basic than a pH of 10.

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The pH ScaleThe pH of a solution is defined as the negative of the common logarithm of the hydronium ion concentration.

pH= -log [H3O+]

The pOH of a solution is defined as the negative of the common logarithm of the hydroxide ion concentration.

pOH= -log[OH-]

[H3O+] 1.0Increasing acidity

1.0x10-7

Increasing basicity1.0x10-14

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pH = -log[H+]

[H+] = 1 x 10-5

when this number is exactly 1

pH = this number without the minus sign.

pH = 5.0

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pH = -log[H+]

[H+] = 2 x 10-5

when this number is between 1 and 10

The number of decimal places of a logarithm is equal to the number of significant figures in the original number.

pH is between this number and next lower number (4 and 5).

one decimal place

one significant figure ph = 4.7

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What is the pH of a solution with an [H+] of 1.0 x 10-11?

pH = - log(1.0 x 10-11)

pH = 11.00

2 decimal places

2 significant figures

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What is the pH of 0.002 M HCl?

[H+] = 2 x 10-3

pH = - log(2 x 10-3)

pH = 2.7

pH calculations – Solving for pH calculations – Solving for H+H+pH calculations – Solving for pH calculations – Solving for H+H+

If the pH of Coke is 3.12, [HIf the pH of Coke is 3.12, [H++] = ???] = ???

Because pH = - log [HBecause pH = - log [H++] , - pH = log [H] , - pH = log [H++]]

Take antilog (10Take antilog (10xx) of both) of both sides and get sides and get

1010-pH -pH == [H[H++]][H[H++] = 10] = 10-3.12-3.12 = 7.6 x 10 = 7.6 x 10-4-4 M M *** to find antilog on your calculator, look *** to find antilog on your calculator, look

for “Shift” or “2for “Shift” or “2nd nd function” and then the log buttonfunction” and then the log button

pH calculations – Solving for H+pH calculations – Solving for H+• A solution has a pH of 8.5. What is the A solution has a pH of 8.5. What is the

Molarity of hydrogen ions in the solution?Molarity of hydrogen ions in the solution?

pH = - log [HpH = - log [H++]]

8.5 = - log [H8.5 = - log [H++]]

-8.5 = log [H-8.5 = log [H++]]

Antilog -8.5 = antilog (log [HAntilog -8.5 = antilog (log [H++])])

1010-8.5-8.5 = [H = [H++]]

3 X 103 X 10-9-9 = [H = [H++]]

pH = - log [HpH = - log [H++]]

8.5 = - log [H8.5 = - log [H++]]

-8.5 = log [H-8.5 = log [H++]]

Antilog -8.5 = antilog (log [HAntilog -8.5 = antilog (log [H++])])

1010-8.5-8.5 = [H = [H++]]

3 X 103 X 10-9-9 = [H = [H++]]

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Autoionization:Water ionizes slightly.

base acid acid baseH2O + H2O → H3O+ + OH- →→

hydronium ion

hydroxide ion

Water ionization equilibrium can be expressed more simply as:

Kw= [H3O+] [OH-] = 1.0 x 10-14 mol/L (This expression can be used to calculate H+ or OH-)

[H3O+] or [H+]= [OH-] = 1.0 x 10-7 mol/L

What is [OH-], if [H+] is 3.0 x 10-3? ( ans: 3.3 X 10 –12 )

Two out of every 1 billion water molecules are ionized.

pOH• Since acids and bases are opposites, Since acids and bases are opposites,

pH and pOH are opposites!pH and pOH are opposites!• pOH does not really exist, but it is pOH does not really exist, but it is

useful for changing bases to pH.useful for changing bases to pH.• pOH looks at the perspective of a pOH looks at the perspective of a

basebasepOH = - log [OHpOH = - log [OH--]]

Since pH and pOH are on opposite Since pH and pOH are on opposite ends,ends,

pH + pOH = 14pH + pOH = 14

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H+ OH-

pH pOH

[H+] = 1.0 X 10 ^-14/ [OH-]

[OH-] = 1.0 X 10 ^-14/ [H+]

pOH

= -log [O

H-]

[OH

-]= 10^

-pO

H

pH=

-log [H+

]

[H+

]= 10^

-pH

pH= 14- pOH

pOH= 14- pH

pH BOX

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1. What is the pH of 0.003 M NaOH?

2. What is [H+], if pH is 3.4?

[OH-] = 3 x 10-3

pOH = - log(3 x 10-3)

pOH = 2.5 14.0-2.5 = 11.5

10 -3.4 = 4 X 10 -4

The pH of rainwater collected in a certain region of the northeastern United States on a particular day was 4.82. What is the H+ ion concentration of the rainwater?

The OH- ion concentration of a blood sample is 2.5 x 10-7 M. What is the pH of the blood?

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The pH of rainwater collected in a certain region of the northeastern United States on a particular day was 4.82. What is the H+ ion concentration of the rainwater?

pH = 4.82[H+] = antilog -4.82 = 1.5 X 10 -5

The OH- ion concentration of a blood sample is 2.5 x 10-7 M. What is the pH of the blood?

[OH-] = 2.5 X 10 -7pOH = 6.6pH = 7.40

Calculating [H3O+], pH, [OH-], and pOH

Problem 1: A chemist dilutes concentrated hydrochloric acid to make two solutions: (a) 3.0 M and (b) 0.0024 M. Calculate the [H3O+], pH, [OH-], and pOH of the two solutions at 25°C.

Problem 2: What is the [H3O+], [OH-], and pOH of a solution with pH = 3.67? Is this an acid, base, or neutral?

Problem 3: Problem #2 with pH = 8.05?

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Problem 1: A chemist dilutes concentrated hydrochloric acid to make two solutions: (a) 3.0 M and (b) 0.0024 M. Calculate the [H3O+], pH, [OH-], and pOH of the two solutions at 25°C.

[H3O+],= 3.0 M pH= -.48, [OH-]=3.3 X 10 -15, and pOH= 14.48[H3O+],= 2.4 X 10 -3 M pH= 2.62, [OH-]=4.2 X 10 -12, and pOH= 11.38

Problem 2: What is the [H3O+], [OH-], and pOH of a solution with pH = 3.67? Is this an acid, base, or neutral?

H3O+],= 2.1 X 10 -4 M, [OH-]=4.8 X 10 -11, and pOH= 10.33 Acidic

Problem 3: Problem #2 with pH = 8.05?

H3O+],= 9.0 X 10 -9 M, [OH-]=1.1 X 10 -6, and pOH= 5.95basic

Equilibria Involving Weak Acids Equilibria Involving Weak Acids & Bases& Bases

Consider acetic acid, HCConsider acetic acid, HC22HH33OO22

HCHC22HH33OO22 + H + H22O O H H33OO++ + C + C22HH33OO22 --

AcidAcid Conj. base Conj. base

Ka [H3O+][OAc- ]

[HOAc] 1.8 x 10-5Ka

[H3O+][OAc- ][HOAc]

1.8 x 10-5

(K is designated K(K is designated Kaa for ACID) for ACID)

K gives the ratio of ions (split up) to molecules (don’t K gives the ratio of ions (split up) to molecules (don’t

split up) when an H+ is removed to form conj. Base.split up) when an H+ is removed to form conj. Base.

Ionization Constants for Acids/Bases Ionization Constants for Acids/Bases

AcidsAcids ConjugateConjugateBasesBases

Increase strength

Increase strength

Equilibrium Constants Equilibrium Constants for Weak Acidsfor Weak Acids

Equilibrium Constants Equilibrium Constants for Weak Acidsfor Weak Acids

Weak acid has KWeak acid has Kaa < 1 < 1

Leads to small [HLeads to small [H33OO++] and a pH of 2 – 7] and a pH of 2 – 7

Water not included because concentration pretty much Water not included because concentration pretty much

stays the same even though plays role in causing stays the same even though plays role in causing

acid to ionizeacid to ionize

Equilibrium Constants Equilibrium Constants for Weak Basesfor Weak Bases

Equilibrium Constants Equilibrium Constants for Weak Basesfor Weak Bases

Weak base has KWeak base has Kbb < 1 < 1

Leads to small [OHLeads to small [OH--] and a pH of 12 - 7] and a pH of 12 - 7

Write the dissociation (ionization) reaction and Ka (omitting water)

for each of the following• A. Hydrochloric Acid

• B. Ammonium ion

• C. C6H5NH3 + (anilinium ion)

• D. Sulfuric Acid

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The Strength of an acid is defined by the equilibrium position of its dissociation reaction.

A strong acid: one for which the equilibrium lies far to the right. Almost all acid is dissociated (ionized). A strong acid yields a weak conjugate base, weaker than water (one that has a low affinity for a proton)

A weak acid: one for which the equilibrium lies far to the left. Most of the acid originally placed in the solution is still present as HA at equilibrium. A weak acid has a conjugate base that is stronger than water.

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Compare the strengths of two acids in the following reactions. What does the strength of acid have to do with the direction in which this reaction occurs? (Forward reaction is

favored, why?)

Base 1

Acid 1

HCl(g) + → Cl-(aq) + H3O+(aq)H2O (l)

Acid

2

Base

2

If strong acid will completely ionize

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Salts can be considered compounds derived from acids and bases. They consist of positive metal or ammonium ions combined with nonmetal ions (OH- and O2- excluded).

Chemists use the terms ionic compound and salt interchangeably.Salts are usually crystalline and have high melting and boiling points.

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NaOH HCl

NaCl

base acid

salt

The positive ion of the salt is derived from the base.

The negative ion of the salt is derived from the acid.

Salt Formation