Acids, Bases and Salts Acid-Base Theories CHAPTER 15 PA 530-538

Acids, Bases and Salts

Acid-Base Theories

CHAPTER 15

PA 530-538

What is an Acid?

The term acid comes from the Latin term acere, which means "sour".

ex. Lemon juice, vinegar, and many other foods taste sour.

Acids Bases

• Taste sour • Corrosive • React with some

metals to produce H2

• Change Litmus to red acid= red

• React with bases to form water and salt.

• Bases taste bitter• Feel slippery• Corrosive• Change Litmus to

blue base = Blue• Become less

basic when mixed with acids.

Always Use Ref. Tables

(vinegar)

Table L Common Bases

• Formula Name

• NaOH(aq) sodium hydroxide• KOH(aq) potassium hydroxide• Ca(OH)2(aq) calcium hydroxide• NH3(aq) aqueous ammonia

Svante Arrhenius 1859 - 1927

Swedish chemist, proposed theories of electrolytic disassociation (acids/bases)

and greenhouse effect.

Arrhenius Theory of Acids & Bases

Acid - produces hydrogen ion (H+) in a solution.

HA H+ + A¯

Base – produces hydroxide ion (OH¯) in a solution.

XOH X+ + OH¯

Nature of the Hydrogen Ion or Proton

• Proton is so small that does not exist isolated in water.

• H+ + H2O H3O +

• Hydronium Ion

Nature of Hydroxide Ion

• The presence of OH- makes the substance an electrolyte and a base.

• Alcohols contain the OH group but are NOT IONIC COMPOUNDS therefore alcohols are NOT bases.

• C H O are molecular compounds NOT ionic compounds!!!!

HOW TO NAME ACIDS

• NO OXYGEN IN FORMULA

• HYDRO ----- ACID

HCl Hydrochloric acid

HBr Hydrobromic acid

HF Hydrofluoric acid

H2S Hydrosulfuric acid

• OXOA CIDS • CONTAIN OXIGEN IN

FORMULA• ENDING

• OUS if ion ends ITE

• IC if ion ends in ATE• Use table E

Solutions of Ionic Compounds conduct electricity = Electrolytes

Electrolytes – ions (charged particles) in solution.

HCl(aq) H+ + Cl-

HydrochloricAcid

H+ Cl -

Solutions

; Release OH- (aq)

Metal (+) and Non-Metal (-)

Electrolytes – conduct electricity when dissolved in H2O

Solutions= Salts (ionic), acids, & bases

Salts = ionic (+) (-)

Strong Acid & Base

Weak Acid or

Weak Base

Covalent = no ions

bright dim dark

Conductivity apparatusElectrolytes – conduct electricity

when dissolved in water

STRONG ACIDS

• COMPLETELY DISSOCIATED

• If the solution is 2 M, 2 mol of H + and 2 mol of Cl-

WEAK ACIDS

• Partially dissociated. Molecules stay together and only some of them dissociate.

HI

HBr

HCl

HNO3

H2SO4

HClO4

LiOH

NaOH

KOH

RbOH

CsOH

Naming Acids

Binary Acids- composed of hydrogen + 1 other element

Ex. HCl Hydrochloric Acid

Binary Acids begin with “hydro -”followed by name of other element; modified with an ending of “-ic”

Ternary Acids - molecular (covalent)- composed of hydrogen + oxygen containing polyatomic ion (Ref. E)

Ex. HNO3 Nitric Acid (NO31- Nitrate ion)

HNO2 Nitrous Acid (NO21- Nitrite ion)

H2SO4 Sulfuric Acid (SO42- Sulfate ion)

Ternary Acids = Anion suffix (-ate or -ite) is dropped and replaced with “-ic” or “-ous” respectively.

TABLE M common acids

• HCl(aq) hydrochloric acid• HNO3(aq) nitric acid

• H2SO4(aq) sulfuric acid

• H3PO4(aq) phosphoric acid

• H2CO3(aq) carbonic acid

• CH3COOH(aq) ethanoic acid

• HC2H3O2(aq) (acetic acid)

Common Acids – Ref. KNitric acid (HNO3)1)  Most is used to make fertilizer

2)  Well known for making explosives

Hydrochloric acid (HCl)1)  Most is used to clean metals (pickling)

2)  Also called muriatic acid

Sulfuric acid (H2SO4) 1)  The most widely used chemical in the world

2)  Most of it is used to make fertilizer

3)  It is a good dehydrating agent

4)  It is used in car batteries

Properties of Bases1) Bases feel slippery

2) Bases are electrolytes

3) Bases are corrosive, poisonous, and can cause severe burns (Lye = conc. NaOH)

4) Bases turn litmus blue; Blue = Base

5) Bases = pH greater than 7

Big in Base

6) Bases neutralize acids

Common Bases – Ref. LAmmonia NH3 1)  The most widely used base

2)  Used in household cleaning materials

3)  Used as fertilizer; adds nitrogen to soil

Calcium hydroxide (caustic lime) Ca(OH)2 1)  Used  to make mortar and plaster

2)  Used to help neutralize acid soil

Sodium hydroxide (Lye) NaOH1)  One of the strongest bases

2)  Used in oven cleaners and drain cleaners

Always Use Ref. TablesAcids ending = “- ic”

Bases = Metal + hydroxide

(vinegar)

Reactions of Acid with metals

• Use table J!• Metals above H2 in table J react with acids

by a single replacement reaction producing H2.

• 2 HCl + Zn H2 + ZnCl2

Neutralization Reaction

Acids and bases react to neutralize each other, forming water and a salt:

Acid + Base Water + Salt

HA + XOH H2O + XA

Double Replacement Reaction

Titration• Is a process that uses a neutralization to

determine the concentration of an acid or a base. Concentration in molarity is the amount of moles of solute per liter of solution. When the reaction of neutralization is 1:1 we use the following formula in a titration

•Ma x Va = Mb x V b

Vocabulary• Standard solution : the solution of known

molarity• Buret : instrument to measure exact

volumes of liquids• Erlenmeyer Flask • Indicator : a substance that changes color in

the presence of an acid or base.• End point: when the amount of H+ = OH-

At the end point

•Ma x Va = Mb x V b

Base

OH -

Acid

H +

Acid – Base Titration

Erlenmeyer flask

Two Burets with valves at bottom.

Record vol. in mL (twice)

Color indicator =

phenolphthalein

What is pH ?

pH is the negative logarithm of the hydrogen ion concentration =

pH = - log [H+]

Remember that sometimes H+ is written H3O

+, so

pH = - log [H3O+]

means the same thing.

pH Scale = log (base 10) scale

An increase of 1 in pH corresponds to a decrease of a factor of 10 in H+ concentration.

pH is.. Big in Base & Blue

Typical pH Values

of CommonMaterials

Oven Cleaner / Drain Cleaner

Hair Remover

Baking Soda

Soap

Ammonia (NH3)

Lemon Juice

Coffee / Tea

Blood

Battery Acid

Saliva

Pure WaterSeawater

Stomach Acid

Milk

Vinegar, Soft Drinks

Tomatoes

Bas

icA

cid

icNeutral

More about pH

Kw = dissociation constant for water = 10-14

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

= [ 10-7 ] x [ 10-7 ]

A neutral solution has a pH of 7.

[H+] = [OH-] = 1 x 10-7 M

pH and [H+]

If pH is… [H+] = ??

pH = 8 _____

pH = 12 _____

pH = 6 _____

pH = 2 _____

Finding pH for a solution of a strong acid or strong base

• For strong acid the concentration of the acid is the same as H+

• For strong bases the concentration of the base is the same as OH-.

Find the pH for

• A) 0.0001 M HCl• B) 0.01 M HBr• C) 0.001 M NaOH

Acid-Base Indicators

• A substance that have different colors at different pH.

Always Use Ref. Tables

(vinegar)

Bronsted Lowry definition

• An ACID is a substance that donates H+

• A BASE is a substance that ACCEPTS H+

P 177 REVIEW BOOK

1) 2

2) 1

3) 1

4) 2

5) 4

6) 4

7) 1

8) 3

9) 2

10)2

11) 4

12)1

13)1

P 181 Review Book

17)4

18)1

19)2

20)4

21)1

22)4

23)4

24)1

25)4

26)4 35)4

27)1 36)3

28)4

29)1

30)4

31)2

32)3

33)4

34)1

P 185 answers

40)4

41)2

42)2

43)1

44)4

45)2

46)25 ml

47)3000ml

48)20mL

49)50mL

50)6M

P 178 rb answers

• 14. chlorate• 15 a) hydrosulfuric acid• b) hydrobromic acid• c) lithium hydroxide• d) magnesium hydroxide• 16. An electrolyte can also be a base or a

salt. An indicator can be added to test if is an acid or a base.

Page 187 answers

61)4

62)1

63)3

64)3

65)3

66)2

67)1

68)1

69)4

70)2

71)Bromocresol green

72)Bet 5.4 and 6

73)A blue

yellow

74) B

75) 1

Handout Answers

1) 2

2) 2

3) 4

4) 2

5) 3

6) 3

7) 4

• pH=6• Methyl orange/

Bromthymol blue• Bromocresol green