Acids & BasesThey are extremely useful in house

holds, industry, and everyday life.

Some smell pretty, some are pretty, some smell bitter and gross.

!! Some are essential to life !!May be hazardous if not used correctly!!!

ACIDSACIDS Acids have a sour tasteAcids contain hydrogen, and some react with

active metals to liberate hydrogen gasAcids react with carbonates to produce CO2

Acids change the color of dyes known as “acid-base indicators”

Produce hydrogen ions when they reactAcids react with bases to produce salts and waterHave pH values less than 7Acids have formulas that begin with HAcids are electrolytes

BASESTaste bitter

Feel slippery to the skin

Change the color of indicators

React to produce hydroxide ions

Have pH values greater than 7

Excellent cleaner. Reacts w/ fats and oils

React with acids to form salts and water

Have formulas that generally end in OH

Are electrolytes

Svante Arrhenius Swedish chemist 1859 – 1927

ACID- is a chemical compd. That increases the concentration of hydrogen ions (H+) & ionizes in aqueous solutions.

H+ is best represented by H3O+= Hydronium ion.

HNO3 + H20 H3O+ + NO3-

HCl + H20 H3O+ + Cl-

Arrhenius BasesBase – increases concentration of

hydroxide ions. (OH-).

H2ONaOH Na + + OH-

Bronsted-Lowry Acid & BaseBronsted-Lowry Acid – is a moleculeOr ion that is a proton donor (hydrogen ion)

Bronsted-Lowry Base – is a molecule or ion that is a proton acceptor (hydrogen ion).

HCl + NH3 NH4+ + Cl-

Which is the acid?Which is the base?

Lewis Acids & Bases1923 – G. N. Lewis – American Chemist

Lewis Acid – atom, ion, molecule thataccepts an electron pair to form a Covalent bond.

Lewis Base – Atom, ion, molecule that donates a pair of electrons to form a Covalent bond.

Strong AcidsStrong AcidsHydrobromic acidSulfuric acid Hydroiodic acid Hydrochloric acid Perchloric acid Nitric acidPhosphoric acid All other acids are weak!!

Strong AcidsAcid strength increases as polarity increases and bond energy decreases.

Strong acids ionize or dissociate completely

Strong BasesAll hydroxides of group IA and most of IIA are strong bases

Strong bases ionize or dissociate completely

Weak acids and bases dissociate less than 5 %.

Dissociation

Dissociation Monoprotic vs. Diprotic vs. Polyprotic

Donates 1 proton

Donates 2 protonsDonates 2 + protons

HClH2SO4

H3PO4

Triprotic

Neutralization Reactions

Acids + Bases neutralizes each other to yield a salt + water.

Acid + Base Salt + H2O

HCl + NaOH NaCl + H2O

Neutralization Reactions

• Acid + Base

• HCl + NaOH

• HF + NH3

• H2SO4 + KOH

Salt + Water

H2O + NaCl

NH4+ + F -

H2O + K2SO4

pH Scale – Pouvoir HydrogènepH is defined as a negative of the

common logarithm of the [H3O+].

pH scale ranges from 0 to 14

pH<7 AcidpH=7 NeutralpH>7 Base

Indicators change color with pH.

Types of indicators

Universal indicator pink – acid/ purple –

baseLitmus paperphenolphthalein

Indicators

Self Ionization of Water• Water can collide with itself to form ions

H2O + H2O H3O+ + OH-

or

H2O H+ + OH-

KKww

• The ion product constant Kw is the same for all solutions.

• Kw = [H+][OH-] = 1*10-14

• In acidic solutions [H+] > [OH-]

• In basic solutions [H+] < [OH-]

Practice

If [H+] = 1*10-3, what is the [OH-]?

143 101]][101[ OH

[H+][OH-] = 1*10-14

3

14

3

3

101

101

]101[

]][101[

OH

[OH-] = 1*10-11M

Determining pH

pH = - log [H3O+]

pH = - log [ 1.0 X 10 –3M]

pH = 3.0

or pH = - log [H+]

-log(1.0E-3)

pOH = Base

pOH = -log [OH-]

If pOH is needed and pH is known, subtract pH from 14. Why remember the pH scale goes from 0 to 14? pH + pOH =

14

If [OH-] = 1*10-4M, what is the pH? pOH?

pOH = -log[OH-]

pOH = -log(1*10-

4)pOH = 4

pH + pOH = 14pH + 4 = 14

pH = 10

If pH = 6.0, what is the [H+]? pOH?pH = -log[H+]6.0 = -log[H+]-6.0 =

log[H+]Antilog(-6.0) = antilog (log[H+])1*10-6 =[H+] pH + pOH =

14.06.0 + pOH = 14.0pOH =

8.0

If pH = 5, what is the [OH-]?pH + pOH = 14.05.0 + pOH = 14.0pOH = 9.0 pOH = -

log[OH-]9.0 = -log[OH-]-9.0 = log[OH-]Antilog(-9.0) = antilog

(log[OH-])1*10-9 =[OH-]

Practice calculating pHWhat is the pH of the solution that has 1.0 X 10 –3 M. ?

The pH of human blood is 7.41. Calculate the[H30+]

pH = - log [H30+]

antilog(-7.41)= 3.89 X 10 -8

A solution. @ 25 C has a hydronium concentration of 1.0 X 10 –9. What is the pH level?

Case Study 15 (b)One consequence of acid rain is vividly illustrated by these twophotographs of a forest site in Germany. The one on the left was taken in 1970, the one on the right in 1983. Acid rain in this region has now been reduced, as a result of better control of power plant emissions.

One consequence of acid rain is vividly illustrated by these two

photographs f a forest site in Germany. The one on the left was

taken in 1970, the one on the right 1983. Acid rain in this region

has now been reduced, as a result of better control of power plant

emissions.

Common Acids• Sulfuric Acid

– Fertilizer, refining, metallurgy, and battery acid

– Add to water to liberate heat

• Phosphoric Acid-flavor• Nitric Acid-explosives• Hydrochloric Acid- 0.4% in stomach• Acetic Acid- 4% to 8% in vinegar

Conjugate Acids and Bases

Titrations• The controlled addition and measurement

of the amount of a solution of a known concentration that is required to react completely with a measured amount of a solution of unknown concentration

• Standard solution -a solution that contains a precisely known concentration of a solute