HCl

H2SO4

H3PO4

HNO3

CH3COOH

HF

Hydrochloric acid

Sulfuric acid

Phosphoric acid

Nitric acid

Acetic acid

Hydrofluoric acid

stomach acid, pickling metal

battery acid, # 1 selling chemical

food flavoring

fertilizer, explosives

vinegar

etch glass

NaOH Ca(OH)2 NH4OH

sodium hydroxide calcium hydroxide ammonium hydroxide

pH scale0

7

14

acid

neutral

base

[H+] = [OH-]

Soren Sorenson developed pH scale

pOH = -log [OH-]

kW = [H+] [OH-]

pH = -log [H+]

pH + pOH = 14

(alkalinity)

Arnold Beckman invented the pH meter

H+ + H2O H3O+

proton hydronium ion

kw = 1 x 10-14

Concentrated vs. Dilute

Concentration: Molarity molality Normality

M = molL m =

molkg

H2SO4 2 H1+ + SO42-

3 M “6 M”

Strong / Weak Acid

Strong HA H+ + A- (~100% dissociation)

Weak HA H+ + A- (~20% dissociation)

Ka = [Product][Reactant]

acid dissociation constant

Ka

0.8 H3PO4 3H+ + PO43-

0.0021 HF H+ + F-

H2A 2 H+ + A-

Ka = [H+]2 [A-]

[H2A]

Acid + Base Salt + Water

How would you make calcium sulfate in the lab?

+ CaSO4

ACID

Sour taste, litmus red

Arrhenius – H+ as only ion in water

Brønsted-Lowry – proton donor

BASE

bitter taste, litmus blue

Arrhenius – OH- as only ion in water

Brønsted-Lowry – proton acceptor

H2SO4 Ca(OH)2 + 2 H2O? ?

phenolphthalein colorless pinkacid baseweak strong

bromthymol blue yellow blue

acid basestrong strong

universal indicator R O Y G B I V

pH 4 7 12

litmus paper & pH paper

Indicators

Buffers - salts of weak acids and weak bases that maintain a pH

LeChatelier’s Principle

- acidosis & alkalosis (bicarbonate ion acts as buffer)- darkening glasses- egg shells thinner in summer (warm)

e.g. Aspirin (acetyl salicylic acid) vs. Bufferinlow pH upsets stomach

Acid – Base Concentrations

pH = 3

pH = 7

pH = 11

OH-

H3O+OH-

OH-H3O+

H3O+

[H3O+] = [OH-] [H3O+] > [OH-] [H3O+] < [OH-]

acidicsolution

neutralsolution

basicsolution

co

nc

en

trat

ion

(m

ole

s/L

)

10-14

10-7

10-1

Timberlake, Chemistry 7th Edition, page 332

Amino Acids – Functional Groups

Amine Carboxylic AcidBase Pair

NH21- R- COOH

NH3NH21- NH4

1+

amine ammonia ammonium ion

NH

HH

:

NH

HH

H : 1+

NH

H

:

1-

:

H+ lose H+

Amino Acids – Functional Groups

Amine Carboxylic AcidBase Pair

NH21- R- COOH

O2-

H+

H+

+

http://fig.cox.miami.edu/~cmallery/150/chemistry/sf3x17b.jpg

Water – Amphiprotic

H2OOH1- H3O1+

hydroxide water hydronium ion

NH

HH

:

NH

HH

H : 1+

NH

H

: 1-

:

H+ lose H+

Water – Also Amphiprotic

H2OOH1- H3O1+

hydroxide water hydronium ion

H+ lose H+

Amphiprotic – Act as an acid (proton donor) or base (proton acceptor)

O2-

H+

H+

+

Amino Acids – Functional Groups

H2OOH1- H3O1+

hydroxide water hydronium ion

H+ lose H+

Amphiprotic – Act as an acid (proton donor) or base (proton acceptor)

O2-

H+

H+

+

http://fig.cox.miami.edu/~cmallery/150/chemistry/sf3x17b.jpg

Range and Color Changes of SomeCommon Acid-Base Indicators

Indicators

pH Scale1 2 3 4 5 6 7 8 9 10 11 12 13 14

Methyl orange red 3.1 – 4.4 yellow

Methyl red red 4.4 6.2 yellow

Bromthymol blue yellow 6.2 7.6 blue

Neutral red red 6.8 8.0 yellow

Phenolphthalein colorless 8.0 10.0 red colorless beyond 13.0

Range and Color Changes of SomeCommon Acid-Base Indicators

Indicators

pH Scale1 2 3 4 5 6 7 8 9 10 11 12 13 14

Methyl orange red 3.1 – 4.4 yellow

Methyl red red 4.4 6.2 yellow

Bromthymol blue yellow 6.2 7.6 blue

Neutral red red 6.8 8.0 yellow

Phenolphthalein colorless 8.0 10.0 red colorless beyond 13.0

pH Paper

pH 0 1 2 3 4 5 6

pH 7 8 9 10 11 12 13

pH Paper

pH 0 1 2 3 4 5 6

pH 7 8 9 10 11 12 13

pH Paper

pH 0 1 2 3 4 5 6

pH 7 8 9 10 11 12 13

pH Paper

pH 0 1 2 3 4 5 6

pH 7 8 9 10 11 12 13

Neutralization of Bug Bites

Wasp - stings with base

(neutralize with lemon juice or vinegar)

Red Ant - bites with acid

(neutralize with baking soda)

StrengthStrength

Strong Acid/BaseStrong Acid/Base• 100% ionized in water• strong electrolyte

- +

HCl

HNO3

H2SO4

HBr

HI

HClO4

NaOH

KOH

Ca(OH)2

Ba(OH)2

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

StrengthStrength

Weak Acid/BaseWeak Acid/Base• does not ionize completely• weak electrolyte

- +

HF

CH3COOH

H3PO4

H2CO3

HCN

NH3

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Ionization of WaterIonization of Water

H2O + H2O H3O+ + OH-

Kw = [H3O+][OH-] = 1.0 10-14

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Why is pure water pH = 7?Why is pure water pH = 7?

1 in 500,000,000 water molecules will autoionize.

H2O + H2O H3O+ + OH1-

This yields a hydronium ion concentration of 1 x 10-7 M H3O+ per liter of solution

pH = -log[H3O+]

pH = -log[1 x 10-7] or pH = 7

HH

OHH

HH

HHO

HH1-

1+

HHO

HH

HH

O HH

HH

OHH

HH O

HH

O

HH

HH

HH

O

HH

Ionization of WaterIonization of Water

Find the hydroxide ion concentration of 3.0 10-2 M HCl.

[H3O+][OH-] = 1.0 10-14

[3.0 10-2][OH-] = 1.0 10-14

[OH-] = 3.3 10-13 M

Acidic or basic?AcidicCourtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

pH = -log[H3O+]

pH ScalepH Scale

0

7INCREASING

ACIDITY NEUTRALINCREASING

BASICITY

14

pouvoir hydrogène (Fr.)“hydrogen power”

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

pH ScalepH Scale

pH = -log[H3O+]

pOH = -log[OH-]

pH + pOH = 14

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

pH ScalepH Scale

What is the pH of 0.050 M HNO3?

pH = -log[H3O+]

pH = -log[0.050]

pH = 1.3

Acidic or basic?Acidic

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

pH ScalepH Scale

What is the molarity of HBr in a solution that has a pOH of 9.6?

pH + pOH = 14

pH + 9.6 = 14

pH = 4.4

Acidic

pH = -log[H3O+]

4.4 = -log[H3O+]

-4.4 = log[H3O+]

[H3O+] = 4.0 10-5 M HBrCourtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Resources - Acids and Bases

Objectives

Worksheet - vocabulary

Worksheet - pH and pOH calculations - pH and pOH calculations

Worksheet - practice problems (key)

Textbook - text ?'s chemical equilibrium

Worksheet - weak acid, pKWorksheet - weak acid, pKaa

Article - aspirinArticle - aspirin

Lab - synthesis of aspirin

Worksheet - aqueous acids and bases titration

Outline ((general)

Video (VHS) - future of the past

Outline - Outline -

Worksheet - Worksheet -

Worksheet - Worksheet -

Worksheet - Worksheet -

Worksheet - Worksheet -

Lab - titrationLab - titration

Textbook - questionsTextbook - questions

Episode 16 – The Proton in Chemistry