Acid and Base Theory Part 1

8/6/2019 Acid and Base Theory Part 1

http://slidepdf.com/reader/full/acid-and-base-theory-part-1 1/30



� What characterizes a molecule as an acid?

� What do all acids have in common?

Compound Formula Found in Electricalconductivity Taste

Citric acid HC6H7O7 Lemon juice Fair Sour

Phosphoric acid H3PO4 Gatorade Fair Sour

Acetic acid HC2H3O2 Vinegar Fair Sour

Boric acid H3BO3 Eyewash Fair SourOxalic acid H2C2O2 Rhubarb Fair Sour

Carbonic acid H2CO3 Soda pop Fair Sour

Hydrochloric acid HCl Stomach acid Good Sour in

dilute



� All carry the name acid

� All conduct electricity to some degree

� All have sour taste� The element common to all members of the

group is hydrogen



a. Produce H+ (as H3O+) ions in water (the hydronium

ion is a hydrogen ion attached to a water molecule)

b. Taste sour

c. Corrode metals

d. Electrolytes

e. React with bases to form a salt and water

f. pH is less than 7



� What characterizes a molecule as a base?

� What do all bases have in common?

NaOH Sodium hydroxide Iye

KOH Potassium hydroxide Liquid soap

Ba(OH)2

Barium hydrox

ide Stabilizer forplastics

Mg(OH)2 Magnesium hydroxide Milk of magnesia

Al(OH)3 Aluminium hydroxide Antacid



a. Produce OH- ions in water

b. Taste bitter, chalky

c. Are electrolytes

d. Feel soapy, slippery

e. React with acids to form

salts and water

f. pH greater than 7



� Electrical conductivity:

Molecules came apart into ions

� Acids:

Molecule that ionized to give up hydrogen ions

A A-H H+



Acids

produce H+ ions (or hydronium ions H3O+)

Bases

produce OH- ions

(problem: some bases dont have hydroxide ions)





Acids proton donor

Bases proton acceptor

A proton is really just a hydrogen atom that has lost itselectron!



� Acid is a proton donor� Base is a proton acceptor

Base Acid



� Which of the following compounds could not

possibly an acid?

H2O CuSO4 NaHCO3 CH3COOH

� Why is your selection in question 1 correct?

� In the following reactions, which compound isthe acid?

HNO3 + NH4OH NH4NO3 + H2O



HNO3 + H2O H3O+ + NO3-

Acid Base hydronium nitrate

ion ion

HNO3 + H2O H3O+ + NO3-

Acid Base

HNO3 + H2O Q H3O+ + NO3-

Acid Base conj. Acid conj. Base



A Brønsted-Lowry acid is a proton donor

A Brønsted-Lowry base is a proton acceptor

acid conjugatebase

base conjugateacid



Label the acid, base, conjugate acid, and

conjugate base in each reaction:

HCl + OH- Cl- + H3O +HCl + OH- Cl- + H3O +

H2O + HC2H3O2 C2H3O2- + H3O+H

2O + HC2H3O2 C2H3O2- + H3O+



Increasingtendency to

capture Hydrogen

ion

Molecule or Ion Molecule or

Ion

Increasing

tendency to

give up

Hydrogen ion

Hydrobonate

ionxide ion

OH- + H+ H2O Water

Carbonate ion CO32- + H+

HCO3- Bicarbonate

ion

Ammonia NH3 + H + NH4+ Ammonium

ion

Bicarbonate ion HCO3- + H+

H2CO3 Carbonic

acid

Acetate ion C2H3O2- + H+

HC2O3O2

Acetic acid

Hydrogen

phosphate ion

H2PO4 + H+

H3PO4

Phosphoric

aicd

Sulfate ion SO42- + H+

HSO4- Bisulfate ion

Water H2O+ + H+ H3O+ Hydronium

ion

Nitrate ion NO3- + H+

HNO3 Nitric acid

Chloride ion Cl- + H + HCl Hydrochloric

acid

Bisulfate ion HSO4- + H+

H2SO4 Sulfuric acid

Perchlorate ion ClO4- + H +

HClO4 Perchloric

acid



� Suppose that HCl is placed in water. Will HCl

give up a hydrogen ion to water, forming

hydronium ion and chloride ion?

� If acetic acid is placed in water, will the acetic

acid molecule donate a hydrogen ion to waterto make the hydronium ion?



� Strong acid:

Transfer all proton to water,

Strong electrolyte



Weak acids:



Hydronium ion is found in a wide range of concentrations in water solutions.

Its concentrations ranges from 10-1 mol /

L (0.1 M

) in strongly acidic solutions to 10-14

(o.00000000000001 M) in strongly basic solutions

The term pH was developed to make it easier towrite about hydronium ion concentration

pH = - log [ H3O+]





� pH = - log [H+] Remember the concentration [] means Molarity

Example: the concentration of hydronium ions inwater is :

[H3O+] = 0.0000001 mol/L

[H

3O+

] = 1x

10

-7

MAnd if pH =- log [H3O+]pH = - log [1o-7]pH = 7



Example: If [H+] = 1 X 10-10

pH = - log 1 X 10-10

pH = - (- 10)pH = 10

Example: If [H+] = 1.8 X 10-5

pH = - log 1.8 X 10-5

pH = - ( - 4.74)

pH = 4.74



Find the pH of these:

1) A 0.15 M solution of Hydrochloric acid

1) A 3.00 X 10-7 M solution of Nitric acid



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

Because pH = - log [H+] then

- pH = log [H+]

Take antilog (10x) of bothsides and get

10-pH = [H+][H+] = 10-3.12 = 7.6 x 10-4 M



� A solution has a pH of 8.5. What is the

Molarity of hydrogen ions in the solution?



H2O can function as both an ACID and a

BASE.

In pure water there can beIn pure water there can beAUTOIONIZATIONAUTOIONIZATION

Equilibrium constant for water = Kw

Kw = [H3O+

] [OH-

] = 1.00 x 10-14

at 25 o

Cc



Kw = [H3O+] [OH-] = 1.00 x 10-14 at 25 oCIn a neutral solution [H3O+] = [OH-]

so Kw = [H3O+]2 = [OH-]2

and so [H3O+] = [OH-] = 1.00 x 10-7 M

OH-

H3O+

OH-

H3O+

Autoionization



� Since acids and bases are opposites, pH andpOH are opposites!

�

pOH does not really exist, but it is useful forchanging bases to pH.

� pOH looks at the perspective of a basepOH = - log [OH-]

Since pH and pOH are on opposite ends,pH + pOH = 14



What is the pH of the

0.0010 M NaOH solution?

The OH- ion concentration of a blood sample is

2.5 x 10-7 M. What is the pH of the blood?

Documents

Acid and Base Theory Part 1