Acids & Bases

I. Properties of Acids & Bases -_____ taste ____ and produce a _______ sensation to the touch

Hydrangea – the color varies depending on the relative acidity or basicity of the soil

-______ acid and ________ acid, (also known as _______ __), are _____ _____ responsible for the _______ of ______ and other ______, while ______ ____ makes _______ taste ____, and in our body, the unpleasant ________ and _______ _________ produced by our _____ is due to ___________ ____ in our ________

acids sourburning

citric ascorbicVitamin C

weak acidstartness citrus

fruits

sournessburning sensation

vomit hydrochloricacid stomach

acetic acidvinegar sour

Acids & Bases

I. Properties of Acids & Bases -because _____ ____ and _______ ________, (and all ______ ______ are made of _______), in ______, they are often used as a _______

acids burn denatureproteins living things

proteins naturedefense

-____, ____, ______, and ______ all use ______ ____ to ______ themselves, while the human _______ is guarded against _______

by ___________ ____, the human ______ is guarded against _______ by ______ ____ (produced by _____- _________ _______ of the genus ___________), and even human ____ is guarded by ____ ____ in our _____

bees ants nettles onionsformic acid defend

stomach bacteriahydrochloric acid

vagina bacterialactic acid

sugar fermenting bacteriaLactobacillus

skin uricacid sweat

Stinging Nettle

Acids & Bases

I. Properties of Acids & Bases -_____ react with ______, especially the more ______ ______, to produce ________ ___

acids metalsactive metals

hydrogen gas

2HCl (aq) 1ZnCl2 (aq)1Zn (s) + 1H2 (g)+

6HNO3 (aq) 2Al(NO3)3 (aq)2Al (s) + 3H2 (g)+

-_____ react with _________ and ________ _________ to produce ______ _______

acids carbonateshydrogen carbonatescarbon dioxide

2HCl (aq) 1CaCl2 (aq)1CaCO3 (s) + 1H2O (l)+

HC2H3O2 (aq) 1NaC2H3O2 (aq)1NaHCO3 (s) + 1H2O (l)+

1CO2 (g)+

1CO2 (g)+

They don’t justtaste “chalky”,

they are chalk!

Acids & Bases

I. Properties of Acids & Bases

Write the balanced thermochemical equation for the reaction that occursbetween:

1. Magnesium and Nitric acid

2. Aluminum and Sulfuric acid

3. Calcium carbonate and Hydrobromic acid

4. Potassium Hydrogen carbonate and Hydrochloric acid

2HNO3 (aq) 1Mg(NO3)2 (aq)1Mg (s) + 1H2 (g)+

3H2SO4 (aq) 1Al2(SO4)3 (aq)2Al (s) + 3H2 (g)+

2HBr (aq) 1CaBr2 (aq)1CaCO3 (s) + 1H2O (l)+ 1CO2 (g)+

1HCl (aq) 1KCl (aq)1KHCO3 (s) + 1H2O (l)+ 1CO2 (g)+

Acids & Bases

I. Properties of Acids & Bases

A. Safety:

1. Hypothesis: Which common household materials are acids or bases?

2. Prediction:

3. Gather Data:

The acids and bases used in this lab are mildly corrosive and cause irritation of the skin, eyes, and mucous membranes. Avoid contact. Use caution. Goggles mandatory.

B. Procedure:

1. Using a pipette, place 3 or 4 drops of each solution in a separate test well of a microplate.

Acids & Bases

I. Properties of Acids & Bases

3. Gather Data:

B. Procedure:

2. Test each liquid with litmus paper. Record results.

3. Test each liquid with 2 drops of phenolphthalein. Record results.

Great Value™

Glass

Cleaner

Chlorox®

Bleach

Sprite® Hy-Vee®

Vinegar

Parson’s®

All-Purpose Cleaner

Hy-Vee®

Orange

Juice

Litmus

Color

(blue or pink)

Phenolphthalein

Color

(clear or pink)

Acid or Base

Acids & Bases

II. Ions in Solutions of Acids & Bases -the relative amounts of ____ and ____ ions in ________ _______ determine the _______ ______, _______, or ________ of the ________

H+

OH- aqueoussolutionrelative aciditybasicity neutrality

Red tulip changes color in varying pH

Purple iris changes color in varying pH

solution

-an _______ _______ that contains more ___ than ____ is an ______ _______

aqueous solutionH+ OH-

acidic solution

-an _______ _______ that contains more ____ than ___ is an _____ _______

aqueous solutionOH- H+

basic solution

-an _______ _______ that contains _____ amounts of ___ and ____ is _______

aqueous solutionequal

H+ OH- neutralhttp://bradley.bradley.edu/~campbell/demopix5.html

Acids & Bases

II. Ions in Solutions of Acids & Bases -_______ ________ that are neither ______ or _____ are _______, but _____ is _______ because it is ____ an ____ and a ____ at the same time, containing _____ amounts of ___ and ____

aqueous solutionsacids bases

neutral waterneutral both

acid baseequal

H+ OH-

Purple carnation changes color in varying pH

Peony changes color in varying pH

http://bradley.bradley.edu/~campbell/demopix5.html

-because of its _______, _____ ___________:

polaritywater self-ionizes

1H2O(l) 1H+ (aq) + 1OH-

(aq)

-but the ___ forms a _______ _____ with a ______ _____ ________, producing the __________ ____

H+ covalentbond another watermoleculehydronium ion

2H2O(l) 1H3O+(aq) + 1OH-

(aq)

Acids & Bases

III. The Arrhenius Model of Acids and Bases

-according to ______ _________, an ____ is a ________ that contains ________ and _______ to produce ________ ____ in _______ _______

Svante August Arrhenius1859 - 1927

Svante Arrheniusacid substancehydrogen ionizeshydrogen ions aqueous solution

-according to _________, ________ ________ is an _____

Hydrogenchloride

Arrheniusacid

1HCl (g) 1H+ (aq) 1Cl-

(aq)+

-according to _________, a _____ is a ________ that contains a _________ _____ and _________ to produce _________ _____ in _______ ________

Arrhenius basesubstance hydroxidegroup dissociateshydroxide ions aqueous solution

-according to _________, ________ _________ is a _____

Arrhenius Sodiumhydroxide base

1NaOH (s) 1Na+ (aq) 1OH-

(aq)+

Acids & Bases

IV. The Brønsted –Lowry Model of Acids and Bases

Johannes Nicolaus Brønsted1879 - 1947

Thomas Martin Lowry1874 - 1936

-according to ________-______, an _____ is a _________-____ ______ and a _____ is a ________- ____ ________

Brønsted Lowryacid hydrogen ion

donor basehydrogen ion acceptor

1H2O (l) 1H3O+(aq)1HX (aq) + 1X-

(aq)+Acid Base Conjugate

AcidConjugate

Base

-the _____, ______, _________ in _____ and _______ a ________ ____ to a ______ ________, which acts as a _____ by ________ the ________ ____

acid HX (aq) dissolveswater donates

hydrogen ion watermolecule base

accepting hydrogen ion

-a ____ that has ________ a ___ now has the ability to ______ a ___, and so becomes an _____; the _________ _____

base accepted H+

donateH+ acid

conjugate acid

Acids & Bases

IV. The Brønsted –Lowry Model of Acids and Bases

-according to ________-______, a _________ ____ is the ______ produced when a ____ accepts a ________ ___ from an ____

Brønsted Lowryconjugate acid species

basehydrogen ion acid

1H2O (l) 1H3O+(aq)1HF (aq) + 1F-

(aq)+Acid Base Conjugate

AcidConjugate

Base

-a _________ ____ is the ______ that is left over from the ____ after it donates a ________ ____

conjugate base speciesacid

hydrogen ion

Playing Hacky Sack in Zurich, Switzerland http://zurichdailyphoto.blogspot.com/2007/04/hacky-sack.html

How is playing Hacky Sack Like ConjugateAcid-Base Pairs?

Player passing Footbag

Footbag

Player receiving Footbag

Conjugate acid

Acid

Hydrogen ion

Base

Conjugate base

Player who passed Footbag

Player who received Footbag

Acids & Bases

IV. The Brønsted –Lowry Model of Acids and Bases

Label the acid, base, conjugate acid, and conjugate base in the following:

1H2O (l) 1NH4+

(aq)1NH3 (aq) + 1OH- (aq)+

1H2O (l) 1H3O+(aq)1HBr (aq) + 1Br-

(aq)+

1H2O (l) 1HCO3-(aq)1CO3

2- (aq) + 1OH- (aq)+

1H2O (l) 1H3O+(aq)1HSO4

- (aq) + 1SO42-

(aq)+

AcidBase ConjugateAcid

ConjugateBase

Acid Base ConjugateAcid

ConjugateBase

AcidBase ConjugateAcid

ConjugateBase

Acid Base ConjugateAcid

ConjugateBase

Substances that can act asboth an acid and a baseare called amphoteric,

as water is in these examples.

Acids & Bases

V. Monoprotic & Polyprotic Acids -____ and ___ are _____ according to the _________ _____ because they both contain _________ and they both donate a ________ ___ to an _______ ________

HCl HF acidsArrhenius

modelhydrogen

hydrogen ion aqueoussolution

Chemical burns caused by Hydrofluoric acid

-both ____ and ___ are also __________ _____ because each donates only ____ _________ ___ per ________

HCl HFmonoprotic acids

onehydrogen ion molecule

-_____ (______ _____), ______ (_________ _____), ____ (____________ _____), and _________ (______ or ________ _____) are other __________ ______

HNO3 Nitric acid HClO4

Perchloric acid HBrHydrobromic acid

CH3COOH aceticethanoic acidmonoprotic acids

CH

H

H

CO

O

H

Even though acetic acid has 4 hydrogenatoms, only 1 of the 4 has a polar enough

bond to be ionizable. The other 3 arepractically nonpolar bonds.

http://www.emedicine.com/emerg/topic804.htm

Acids & Bases

V. Monoprotic & Polyprotic Acids

CH

H

C

C

H

C

C

C

H

H

H

Benzene has 6 hydrogen atoms, but none of the covalent bonds

are polar enough to be ionizable,so benzene is not an acid at all.

-_____ that donate _____ than ____ _________ ___ are called _________

acids moreone hydrogen ionpolyprotic

-______(_______ _____) and ______(________ _____) are both _______ _____, while ______ (__________ ____) and ______ (______ _____) are both _________ ______

H2SO4

H2CO3

Sulfuric acidCarbonic acid

diprotic acidsH3PO4 Phosphoric acidH3BO3 Boric acid

triprotic acids

SO

O

O

OH

H

PO

O

O

OH

H

H

Sulfuric acid contains 2highly polar ionizable

covalent bonds

Phosphoric acid contains 3 highly polar ionizable

covalent bonds

Acids & Bases

V. Monoprotic & Polyprotic Acids -__________ _____ donate more than ____ ________ ____ to _______ _______ in more than ___ step

polyprotic acidsone hydrogen ion

aqueous solutionone

1H2O (l) 1H3O+(aq)1H3PO4 (aq) + 1H2PO4

- (aq)+

1H2O (l) 1H3O+(aq)1H2PO4

- (aq) + 1HPO42-

(aq)+

1H2O (l) 1H3O+(aq)1HPO4

2- (aq) + 1PO43-

(aq)+

-the ________ ____ __________ ____ donates __ ________ ____ in __ steps:

triprotic acid3 hydrogen ions

3

Phosphoricacid

PO

O

O

OH

H

H

Acids & Bases

V. Monoprotic & Polyprotic Acids

Write the steps for complete ionization of the following polyprotic acids:

H2Se (aq)

H3AsO4 (aq)

H2SO3 (aq)

H2O (l) H3O+(aq)+ 1HSe-

(aq)+

H2O (l) H3O+(aq)HSe- (aq) + Se2-

(aq)+

H2O (l) H3O+(aq)+ H2AsO4

- (aq)+

H2O (l) H3O+(aq)H2AsO4

- (aq) + HAsO42-

(aq)+

H2O (l) H3O+(aq)HAsO4

2- (aq) + AsO43-

(aq)+

H2O (l) H3O+(aq)+ HSO3

1- (aq)+

H2O (l) H3O+(aq)HSO3

1- (aq) + SO32-

(aq)+

Acids & Bases

VI. Acid & Base Anhydrides -__________ are _______ that form _____ and _____ when added to ______

anhydrides oxidesacids baseswater

1H2O (l) 1H2CO3 (aq)1CO2 (g) +

1H2O (l) 1HNO3 (aq)2NO2 (g) + + 1HNO2 (aq)

1H2O (l) 1H2SO3 (aq)1SO2 (g) +

1H2O (l) 1H2SO4 (aq)1SO3 (g) +

-______ of ___________ elements produce _____ in _______ _______, while ______ of ________ elements produce _____ in _______ ________

oxides nonmetallicacids aqueous solution

oxides metallicbases aqueous solution

1H2O (l) 1Ca2+ (aq)1CaO (s) + + 2OH-

(aq)

1H2O (l) 1Mg2+ (aq)1MgO (s)+ + 2OH-

(aq)

Acids & Bases

VII. Strength of Acids -______ _____ are _____ that ______ _________

strong acids acids ionizecompletely

1H2O (l) 1H3O+ (aq)1HCl (aq) + + 1Cl-

(aq)

-____ (___________ _____), ______ (__________ _____), _____ (______ ____), ____ (____________ _____), ______ (________ _____), and ___ (___________ _____) are all ______ _____

HCl Hydrochloric acid HClO4

Perchloric acid HNO3 Nitric acidHBr Hydrobromic acid H2SO4

Sulfuric acid HI Hydroiodicacid strong acids

-______ _____ are _____ that ______ only ________

weak acids acids ionizepartially

HC2H3O2 (aq) H2O (l) H3O+(aq)+ C2H3O2

- (aq)+

-________ (______ _____), ______ (________ _____), ___ (___________ ____), ______ (_____ _____), and _____ (___________ ____) are _____ _____

HC2H3O2 Acetic acid H2CO3

Carbonic acid HF Hydrofluoricacid H3BO3 Boric acid HCNHydrocyanic acid weak acids

Hydrofluoric acid is considered a weak acid because it doesn’t ionize

completely; it is expected to be a strong acid, because it is so corrosive, but its corrosiveness is due to the chemical reactivity of its anion, the fluoride ion.The strongest acids, the carborane

superacids, are a million times strongerthan concentrated sulfuric acid, but not

at all corrosive because the anion tothe acid is so unreactive.

Acids & Bases

VII. Strength of Acids -according to ______________, the ____ on the _______ side of the ________ _______ produces a ________ ____ on the ________ side of the _______ _______ by _______ a ________ ___

Brønsted-Lowry acidreactant forward reaction

conjugate base productforward reaction donating

hydrogen ion

1H2O (l) 1H3O+(aq)1HX (aq) + 1X-

(aq)+Acid Conjugate

Base

-if the ____ is a ______ ____, then its _________ ____ is _____, that is, if the ____ readily _______ a ________ ___, then its ________ ____ is not very good at ________a ________ ___, or holding on to one, while a ____ ____, which is not very good at _______ a ________ ___ has a ______ ________ ____

acid strong acidconjugate base weakacid donates hydrogen ion

conjugate baseaccepting hydrogen ion

weak aciddonating hydrogen ion

strong conjugate base

Acids & Bases

VII. Strength of Acids

-the __________ ________ __________ for the _________ of ____________ _____ is:

equilibrium constant expressionionization Hydrocyanic acid

Keq = [H3O+]1

[HCN]1

[CN-]1

[H2O]1

-the ___________ of ______ _____ is considered to be _______, and so can be _________ with ___ to give the _____ _________ _______, or ___

concentration liquid waterconstant

combined Keq acidionization constant Ka

Ka = [H3O+]1

[HCN]1

[CN-]1

1HCN (aq) 1H2O (l) 1H3O+(aq)+ 1CN-

(aq)+

-the _________ ________ for ___________ _____ is:

ionization equation Hydrocyanicacid

Acids & Bases

VII. Strength of Acids

Write ionization equations and acid ionization constant expressions for the following acids:

H2O (l) H3O+(aq)HClO2 (aq) + ClO2

- (aq)+

HNO2 (aq)

HIO (aq)

Ka = [H3O+]1

[HClO2]1

[ClO2-]1

H2O (l) H3O+(aq)+ NO2

- (aq)+

Ka = [H3O+]1

[HNO2]1

[NO2-]1

H2O (l) H3O+(aq)+ IO-

(aq)+

Ka = [H3O+]1

[HIO]1

[IO-]1

Acids & Bases

VIII. Strength of Bases-______ _____ are _____ that _________ _________

strong bases bases dissociatecompletely

1Na+ (aq)1NaOH (s) + 1OH-

(aq)

-______ (_______________), _____ (_________________), ______ (_________ _________), _____ (_______________), _______ (________________), and ______ (_______________) are all ______ _____

NaOH Sodium hydroxide KOHPotassium hydroxide

-______ _____ are _____ that ________ only ________

weak bases bases dissociatepartially

-________ (___________), ________ (__________), ____ (________), and ________ (______) are all _____ ______

CH3NH2

RbOH Rubidiumhydroxide CsOH Cesium hydroxideCa(OH)2 Calcium hydroxide Ba(OH)2Barium hydroxide strong bases

CH3NH2 (aq) H2O (l) CH3NH3+

(aq)+ OH- (aq)+

methylamine C2H5NH2

ethylamine NH3 ammoniaC6H5NH2 aniline weak bases

Acids & Bases

VIII. Strength of Bases

-the ____ __________ ________ __________ for the _________ of ___________ is:

acid ionization constantexpression ionizationhexylamine

Kb = [OH-]1

[C6H13NH2]1

[C6H13NH3+]1

1C6H13NH2 (aq) 1H2O (l) 1OH-(aq)+ 1C6H13NH3

+ (aq)+

-the ________ ________ for __________ is:ionization equation hexylamine

Base ConjugateAcid

Acid ConjugateBase

CH

H

H

C

H

H

C

H

H

C C

H

H

H

H

C

H

H

N

H

H

Hexylamine

Acids & Bases

VIII. Strength of Bases

Write ionization equations and base ionization constant expressions for the following bases:

H2O (l) OH-(aq)C3H7NH2 (aq) + C3H7NH3

+ (aq)+

CO32-

(aq)

HSO3- (aq)

Kb = [OH-]1

[C3H7NH2]1

[C3H7NH3+]1

H2O (l) OH-(aq)+ HCO3

- (aq)+

Kb = [OH-]1

[CO32-]1

[HCO3-]1

H2O (l) OH-(aq)+ H2SO3 (aq)+

Kb = [OH-]1

[HSO3-]1

[H2SO3]1

Acids & Bases

IX. Ion Product Constant for Water -the ________ ________ for ______ is:

ionization equationwater

H2O (l) OH-(aq)H2O (l) + H3O+

(aq)+

Base ConjugateAcid

Acid ConjugateBase

-the ________ ________ can be simplified to:

ionization equation

H2O (l) OH-(aq) H+

(aq)+

-the __________ _______ __________ is:

equilibrium constantexpression

Keq = [OH-]1

[H2O]1

[H+]1

Acids & Bases

IX. Ion Product Constant for Water -since _____ is a ______, its _____________ is equal to its _______, which is _______ at a _______ ___________ and ________, so the __________ _______ _________ can be simplified by __________ both sides by ______, creating the ___ _______ _______ ___ _____, ___

water liquidconcentrationdensity constant

constant temperaturepressure equilibriumconstant expression

multiplying[H2O]

ion product constant forwater Kw

Kw = [OH-]1 [H+]1

-at _____, the ____- _________ of _____ produces ____ = _________ and a ______ = _________, so ___ = _______

298 K self ionizationwater [H+]

1 x 10-7 M [OH-]

1 x 10-7 M Kw 1 x 10-14

Kw = (1 x 10-7)1 (1 x 10-7)1

Kw = 1 x 10-14

Acids & Bases

IX. Ion Product Constant for Water

What is the concentration of the hydroxide ion in an aqueous solution with a hydrogen ion concentration of 1 x 10-5 M? Is the solution acidic, basic, or neutral? Kw = [H+][OH-]

1 x 10-14 = [OH-](1 x 10-5)

[OH-] = 1 x 10-9 M

The solution is acidic, because the [H+] is greater (104) than the [OH-]

What is the concentration of the hydrogen ion in an aqueous solution with a hydroxide ion concentration of 1 x 10-3 M? Is the solution acidic, basic, or neutral? Kw = [H+][OH-]

1 x 10-14 = [H+](1 x 10-3)

[H+] = 1 x 10-11 M

The solution is basic, because the [OH-] is greater (108) than the [H+]

Acids & Bases

X. pH (pondus hydrogenii)

Søren Sørensen1868 - 1939

-in 1909, _____ ________ developed the ___ (________ _________) _____ as a way of conveniently expressing the ___________ of _____ and _____

Søren SørensenpH potential hydrogen scale

concentration acids bases

pH = -log [H+]

What is the pH of water?

pH = -log [H+]

pH = -log (1 x 10-7)

pH = 7.0

What is the pH of an aqueous solution inwhich the [H+] = 1.0 x 10-2 M?

pH = -log [H+]

pH = -log (1.0 x 10-2)

pH = 2.00

The number ofdecimal places inthe pH is equal to

the number of significant digits

in the [H+]1 sig. fig. in [H+],

1 decimal place in pH

2 sig. figs. in [H+],2 decimal place in pH

Acids & Bases

A. Safety:

1. Hypothesis: What is the relationship between the concentration of an acid and its pH?

2. Prediction:

3. Gather Data:

The acids used in this lab are corrosive and cause irritation and damage to the skin, eyes, and mucous membranes. Avoid contact. Use caution. Goggles mandatory.

B. Procedure: Serial Dilution

1. Using a pipette, place 10 drops of 1.0 M HCl in test well 1A of a microplate.

X. pH (pondus hydrogenii)

Acids & Bases

3. Gather Data:

B. Procedure:

2. Rinse the pipette, and transfer 1 drop of acid solution from test well 1A to test well 2A, and add 9 drops of distilled water.

3. Repeat Step 2, transferring 1 drop of acid solution from test well 2A to test well 3A and adding 9 drops of distilled water .

4. Repeat Step 2 six more times, each time transferring 1 drop of acid solution from the previous test well and adding 9 drops of distilled water.

X. pH (pondus hydrogenii)

Acids & Bases

3. Gather Data:

B. Procedure:

5. Test the pH in each well with pH indicator paper. Record.

6. Test the pH in each well with 1 drop of universal indicator solution. Record.

Test

Well

Number

A1 A2 A3 A4 A5 A6 B1 B2

[H+]

Concentration

pH

paper

pH

Universal

Indicator

X. pH (pondus hydrogenii)

Acids & Bases

4. Analyze Data:

A. What is [H+] in test well A4? ________________.

B. What is [H+] in test well A6? ________________.

C. What is the theoretical pH in test well A2? _______________.

D. What is the theoretical pH in test well B2? _______________.

A. Each step in the serial dilution ____________ the concentration of the hydrogen ion by a factor of _______ and __________ the pH by a factor of _______

5. Draw Conclusions:

E. The color of pH paper in test well A1 was _______, indicating an approximate pH of _______.

F. In test well A2 universal indicator was ________ in color.

X. pH (pondus hydrogenii)

Acids & Bases

XI. pOH (potential Hydroxide) -the _______, or ________, of a _______ can be expressed by the ____, or ________ _________:

basicity alkalinitysolutionpOH potential Hydroxide

pOH = -log [OH-]

What is the pOH of water?

pOH = -log [OH-]

pOH = -log (1 x 10-7)

pOH = 7.0

What is the pOH of an aqueous solution inwhich the [OH-] = 1.00 x 10-6 M?

pOH = -log [OH-]

pOH = -log (1.00 x 10-6)

pOH = 6.000

What is the pH of an aqueous solutionin which the [OH-] = 1.0 x 10-3 M?

pOH = -log [OH-]

pOH = -log (1.0 x 10-3)

pOH = 3.00

Kw = [OH-][H+]

= (1 x 10-7)(1 x 10-7)

=

1 x 10-14

14 pH + pOH

pH = 11.00

Acids & Bases

XI. pOH (potential Hydroxide)

What is the pH and the pOH of an aqueous solution with a hydroxide ion concentration of 1.0 x 10-6 M? Is the solution acidic, basic, or neutral?

What is the pH and the pOH of an aqueous solution with a hydroxide ion concentration of 6.5 x 10-4 M? Is the solution acidic, basic, or neutral?

What is the pH and the pOH of an aqueous solution with a hydrogen ion concentration of 3.6 x 10-9 M? Is the solution acidic, basic, or neutral?

pOH = -log [OH-]

pOH = -log (1.0 x 10-6)

pOH = 6.00

=14 pH + pOH

pH = 8.00

basic

pOH = -log (6.5 x 10-4)pOH = 3.19

pH = 10.81basic

pH = -log (3.6 x 10-9)pH = 8.44

pOH = 5.56basic

Acids & Bases

XI. pOH (potential Hydroxide)

What is the hydrogen ion concentration and the hydroxide ion concentration of a person’s blood that has a pH of 7.40 at 298 K?

What is the hydrogen ion concentration and the hydroxide ion concentration of an aqueous solution that has a pH of 2.37 at 298 K?

What is the hydrogen ion concentration and the hydroxide ion concentration of an aqueous solution that has a pH of 11.05 at 298 K?

pH = -log [H+]

7.40 = -log [H+]

[H+] = 4.0 x 10-8 M

=14 7.40 + pOH

6.60 = -log [OH-]

[OH-] = 2.5 x 10-7 M

2.37 = -log [H+]

[H+] = 4.3 x 10-3 M

11.63 = -log [OH-]

[OH-] = 2.3 x 10-12 M

Multiply [H+][OH-]to check your answer

(4.3 x 10-3)(2.3 x 10-12)=Kw

11.05 = -log [H+]

[H+] = 8.9 x 10-12 M

2.95 = -log [OH-]

[OH-] = 1.1 x 10-3 M

Multiply [H+][OH-]to check your answer

(8.9 x 10-12)(1.1 x 10-3)=Kw

Acids & Bases

XII. Calculating pH of Strong Acids and Strong Bases

What is the pH of a 1.0 M HI solution?

1H+ (aq)1HI (aq) + 1I-

(aq)

1.0 M 1.0 M 1.0 M

pH = -log [H+]

pH = -log (1.0)

pH = 0.00

What is the pH of a 0.050 M HNO3 solution?

1H+ (aq)1HNO3 (aq) + 1NO3

- (aq)

0.050 M 0.050 M 0.050 M

pH = -log [H+]

pH = -log (0.050)

pH = 1.30

What is the pOH of a 2.4 x 10-5 M Mg(OH)2 solution?

1Mg2+ (aq)1Mg(OH)2 (s) + 2OH-

(aq)

2.4 x 10-5 M 2.4 x 10-5 M 4.8 x 10-5 M

pOH = -log [OH-]

pOH = -log (4.8 x 10-5)

pOH = 4.32

pH = 9.68

Acids & Bases

XIII. Calculating pH of Weak Acids and Weak Bases

What is Ka of a 0.100 M formic (methanoic) acid solution with pH 2.38?

1HCOO-(aq)1HCOOH (aq) 1H+

(aq)+

Ka = [HCOO-]

[HCOOH]

[H+]

pH = -log [H+]

2.38 = -log [H+]

[H+] = 4.2 x 10-3 M

0.100 M 4.2 x 10-3 M 4.2 x 10-3 M

[HCOO-] = 4.2 x 10-3 M

[HCOOH] = 4.2 x 10-3 M0.100 M -

[HCOOH] = 0.0042 M0.100 M -

[HCOOH] = 0.096 M

Ka = (4.2 x 10-3 )

(0.096 )

(4.2 x 10-3 )

Ka = 1.8 x 10-4

Acids & Bases

XIII. Calculating pH of Weak Acids and Weak Bases

What is Ka of a 0.220 M arsenic acid solution with pH 1.50?

1H2AsO4-(aq)1H3AsO4 (aq) 1H+

(aq)+

Ka = [H2AsO4-]

[H3AsO4]

[H+]

pH = -log [H+]

1.50 = -log [H+]

[H+] = 3.2 x 10-2 M

0.220 M 3.2 x 10-2 M 3.2 x 10-2 M

[H2AsO4-] = 3.2 x 10-2 M

[H3AsO4] = 3.2 x 10-2 M0.220 M -

[H3AsO4] = 0.032 M0.220 M -

[H3AsO4] = 0.188 M

Ka = (3.2 x 10-2 )

(0.188 )

(3.2 x 10-2 )

Ka = 5.4 x 10-3

Acids & Bases

XIII. Calculating pH of Weak Acids and Weak Bases

What is Ka of a 0.0400 M chlorous acid solution with pH 1.80?

1ClO2-(aq)1HClO2 (aq) 1H+

(aq)+

Ka = [ClO2-]

[HClO2]

[H+]

pH = -log [H+]

1.80 = -log [H+]

[H+] = 1.6 x 10-2 M

0.0400 M 1.6 x 10-2 M 1.6 x 10-2 M

[ClO2-] = 1.6 x 10-2 M

[HClO2] = 1.6 x 10-2 M0.0400 M -

[HClO2] = 0.016 M0.0400 M -

[HClO2] = 0.024 M

Ka = (1.6 x 10-2 )

(0.024 )

(1.6 x 10-2 )

Ka = 1.1 x 10-2

Acids & Bases

XIII. Calculating pH of Weak Acids and Weak Bases

What is Ka of a 1.000 M propanoic acid solution with pH 2.43?

1C3H5O2-(aq)1HC3H5O2 (aq) 1H+

(aq)+

Ka = [C3H5O2-]

[HC3H5O2]

[H+]

pH = -log [H+]

2.43 = -log [H+]

[H+] = 3.7 x 10-3 M

1.000 M 3.7 x 10-3 M 3.7 x 10-3 M

[C3H5O2-] = 3.7 x 10-3 M

[HC3H5O2] = 3.7 x 10-3 M1.000 M -

[HC3H5O2] = 0.0037 M1.000 M -

[HC3H5O2] = 0.9963 M

Ka = (3.7 x 10-3 )

(0.9963 )

(3.7 x 10-3 )

Ka = 1.4 x 10-5

Acids & Bases

XIV. Neutralization -when an ____ and a ____ _____, the resulting _______ has _________ that are characteristic of _______ an ____ or a ____

acid base reactsolution properties

neither acid base

-a ____________ _______ is a ______- ___________ _______ in which an ____ and a ____ react in _______ ________ to produce a ____ and _____

neutralization reaction doublereplacement acidbase aqueous solutionsalt water

reaction

2HCl (aq) 1MgCl2 (aq)1Mg(OH)2 (aq) + + 2H2O (l)

Milk of Magnesiais a Magnesium hydroxide

suspension used toneutralize stomach acid

base acid salt water

-a ____ is an _____ _________ made up of the ______ from the ____ and the _____ from the ____

salt ionic compoundcation base anion

acid

-the ___ _____ ________ for a ____________ _______ is:

net ionic equation neutralizationreaction

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

Acids & Bases

XIV. Neutralization

Write the complete balanced thermochemical equations for the followingneutralization reactions and name the products:

Nitric acid + Cesium hydroxide

Hydrobromic acid + Calcium hydroxide

Sulfuric acid + Potassium hydroxide

1HNO3 (aq) 1CsNO3 (aq)1CsOH (aq)+ + 1H2O (l)

baseacid Cesium nitrate water

2HBr (aq) 1CaBr2 (aq)1Ca(OH)2 (aq)+ + 2H2O (l)

acid base Calcium bromide water

2KOH (aq) 1K2SO4 (aq)1H2SO4 (aq) + + 2H2O (l)

acid base Potassium sulfate water

electronic pH meter

Acids & Bases

XV. Titration -a _______is a method for determining an ________ ____________ of a solution by _______ a ______ ______ of a _______ solution of ______ ____________

titration unknownconcentration reacting knownvolume different knownconcentration

-to find the ________ ___________ of a ______ ______ of ____ solution, you can ______ the solution with a ______ ______ of an ____ solution of ______ ____________

unknown concentration knownvolume base titrate

known volume acidknown concentration

1 mL HCl sol. x 1 L HCl sol.______________1000 mL HCl sol.

= 0.001 mole NaOHx 1 mole HCl___________1 L HCl sol.

x 1 mole NaOH_______________1 mole HCl

1HCl (aq) 1NaCl (aq)1NaOH (aq)+ + 1H2O (l)

baseacid salt water

M = 0.001 mole NaOH_______________10 mL NaOH sol.

x 1000 mL NaOH sol._______________1 L NaOH sol.

= 0.1 M NaOH

Acids & Bases

XV. Titration

What is the molarity of a CsOH solution if 30.0 mL of the solution isneutralized by 26.4 mL of 0.250 M HBr solution?

26.4 mL HBr sol. x 1 L HBr sol.______________1000 mL HBr sol.

= 0.00660 mole CsOHx 0.250 mole HBr___________1 L HBr sol.

x 1 mole CsOH_______________1 mole HBr

1HBr (aq) 1CsBr (aq)1CsOH (aq)+ + 1H2O (l)

M = 0.00660 mole CsOH_______________30.0 mL CsOH sol.

x 1000 mL CsOH sol._______________1 L CsOH sol.

= 0.220 M CsOH

What is the molarity of a nitric acid solution if 20.00 mL of the solution is neutralized by 43.33 mL of 0.1000 M KOH solution?

43.33 mL KOH sol. x 1 L KOH sol.______________1000 mL KOH sol.

= 4.333 x 10-3 mole HNO3x 0.1000 mole KOH______________1 L KOH sol.

x 1 mole HNO3_______________1 mole KOH

1HNO3 (aq) 1KNO3 (aq)1KOH (aq)+ + 1H2O (l)

M = 4.333 x 10-3 mole HNO3_______________20.00 mL HNO3 sol.

x 1000 mL HNO3 sol._______________1 L HNO3 sol.

= 0.2167 M HNO3

Acids & Bases

XV. Titration -during the course of a _______, a known _______ of a _______ of known ___________ is added until the __________ _____ is reached, at which the _______ of ______ of ____ equals the _______ of ______ of _____

titration volumesolution concentration

equivalence pointnumber moles H+ numbermoles OH-

-corresponding closely with the __________ _____ is the ___ _____, at which the ________ changes _____

Adding indicator Titrating End Point

equivalence pointend point indicator

color

Acids & Bases

XVI. Buffered Solutions -_______ are _________ that _____ changes in ___

buffers solutions resistpH

-a ______ is a _______ of a _____ ____ and its _________ ____

buffer mixture weak acidconjugate base

HF (aq) H+ (aq) + F-

(aq)

H+ Adding an acid,raising [H+]

HF (aq) H+ (aq) + F-

(aq)

Equilibrium shifts to the left,lowering [H+]

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

(aq)

OH- Adding a base,raising [OH-]

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

(aq)

Equilibrium shifts to the left,lowering [OH-]

Human blood is buffered bythe weak acid carbonic acid(H2CO3) and its conjugatebase, hydrogen carbonate

(HCO3-)

Weak acid Conjugate base

Acids & Bases

XVI. Buffered Solutions -a ______ can also be a _______ of a _____ ____ and its _________ ____

buffer mixtureweak base conjugate acid

NH3 (aq) NH4+

(aq) + OH- (aq)

OH- Adding a base,raising [OH-]

Weak base Conjugate acid

+ H2O (l)

NH3 (aq) NH4+

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

Equilibrium shifts to the left,lowering [OH-]

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

(aq)

H+ Adding an acid,raising [H+]

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

(aq)

Equilibrium shifts to the left,lowering [H+]

Acids & Bases

XVI. Buffered Solutions

What is the pH of buffer system made by mixing equal amounts of H2PO4

- and HPO42-?

H2PO4- (aq) H+

(aq) HPO42-

(aq)+

Ka = [H+]

[H2PO4-]

[HPO42-]

6.2 x 10-8 = [H+]

[H2PO4-]

[HPO42-]

6.2 x 10-8 = [H+](6.2 x 10-8)=pH -log

pH = 7.21