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Credits to:-

Aniket Angadianiket.angadi@live.com

NotesChemistry

Acid, Bases, and SaltsChemistry—Part 1

I. Acids

H is a nonmetal or polyatomic ion could be Cl- , SO4

2-, etc.

Ex: HCl, HF, H2SO4 , HClO4, H3PO4

Acids (con’t)

dissociate to form H+ ions (protons)

Hydrogen Atom Hydrogen Ion (proton)

 +

e-

A. Ionization in Water

HCl + H2O

 H+ combines with H2O to form H3O+

Hydronium Ion

H+(proton) is attracted to lone e- pairs in H2O

H3O+ + Cl-

+-

Try This:

H2SO4 + H2O

H3PO4 + H2O

SO42-

+

+

SO42-

2 H3O+ + SO42-2

3 H3O+ + PO43-3

B. Examples

Soda pop – H2CO3, H3PO4

Vinegar (acetic acid) – HC2H3O2

Lemons – citric acid Stomach acid – HCl Battery acid – H2SO4

Sour Patch Kids – Tartaric Acid

C. Properties

taste sour conduct electricity turn litmus red react with some metals to produce H2

(g) Remember, Zn + 2HCl ZnCl2 + H2(g)

corrosive All form H+ ions in solution

II. Bases

contain OH- (hydroxide ions)Ex: Ca(OH)2, LiOH, NH4OH, NaOH

Also called alkaline (alkali)

Alkali FlatsBonneville Salt Flats, Utah

A. Ionization In Water

NaOH Na+ + OH-

NH4OH

Ca(OH)2  

H2O

H2O

H2O

NH4+ + OH-

Ca2+ + 2 OH-

B. Examples

Drano – NaOH Oven cleaner – KOH Tums – Ca(OH)2

Glass cleaner – NH4OH

C. Properties

Taste bitter (Baking Soda) Conduct electricity Turn litmus blue Feel slippery (hard to wash off of skin) Caustic (dissolves protein, ie. YOU) Form OH- ions

III. Reactions of Acids and Bases

Neutralization:

Acid + Base Salt + Water

HBr + NaOH

Type of reaction? DOUBLE DISPLACEMENT!

NaBr + H2O

Try This:

HF + LiOH

H2SO4 + KOH

HOH + LiF(H2O)

H2O + K2SO42 2

Antacids

Neutralize stomach acid

Ex: TumsHCl + Ca(OH)2

Milk of Magnesia (demo)HCl + Mg(OH)2

H2O + CaCl22 2

H2O + MgCl22 2

IV. Electrolyte Solutions

Substances whose water solutions conduct electricity

  NaCl (c) vs. NaCl (aq) Sucrose (c) vs. Sucrose (aq) H2O (distilled) vs. H2O (tap) 

There must be ions present to conduct

 

Strong & Weak Electrolytes

STRONG ELECTROLYTES

Ionize 100%NaCl

WEAK ELECTROLYTES

Only partially ionizeHF

Na+ + Cl-

H+ + F-

Na+

Na+Cl-

Cl-

NaCl (s)

HF (s)

HF

HFHF

H+

F+

only ions are present

mostly HF present;only some ions

Conductivity Demo

NH4OH + HC2H3O2

Weak Base

Weak Acid

H2O + NH4C2H3O2

Salt

Practice

Salt Parent Acid Parent Base

LiBr

K2CO3

(NH4)2SO4

HBr

H2CO3

H2SO4 NH4OH

KOH

LiOH

H? ?OH

Lab 49 Pre - LabNaCl FeCl3 C6H12O6

Na+ (aq) + Cl- (aq) Fe3+ (aq) + 3 Cl- (aq)

C6H12O6 (aq)

V. Naming Acids, Bases & Salts

Acid Names1. Binary Acids

contain only TWO elementsex: HCl Hydrochloric Acid Hydro-stem-ic AcidTry: HBr

HFH2S

Hydrobromic AcidHydrofluoric AcidHydrosulfuric Acid

1. Ternary Acidscontain THREE elements

(usually)contain H and a polyatomic ion

ate ic ite ousex: H2CO3 carbonate carbonic

Carbonic Acid

Try TheseHNO2

nitrite nitrousNitrous Acid

HNO3

nitrate nitricNitric Acid

H2SO3

sulfite sulfurousSulfurous Acid

H2SO4

sulfate sulfuricSulfuric Acid

Base Names (IUPAC Nomenclature)

Combine names of ions

NaOHSodium Hydroxide

Ca(OH)2

Calcium Hydroxide

Salt Names

Combine names of ions

NaBrSodium Bromide

K2SO4

Potassium SulfateCu(NO3)2

Copper (II) Nitrate

VI. Salts

Salts are ionic and crystalline

A. Dissociation in Water

Salt Cation + Anion

LiCl

Na2SO4

H2O

H2O

H2O

Li+ + Cl-

2 Na+ + SO42-

B. Cation and Anion

Cation: Positive (+) charge

The ___________ contributes the cation(acid/base?)

Anion: Negative (-) charge

The ___________ contributes the anion(acid/base?)

C. Examples

Cation Anion

NaCl

NaHCO3

K2SO4

Na+

K+

Na+

SO42-

HCO3-

Cl-

Parent Acid / Parent Base

Parent Acid: The acid that contributes the ANION to the salt

Parent Base: The base that contributes the CATION to the salt

VIII. Strong Acids and Bases

STRONG ACIDS—DISSOCIATE 100 %HCl HNO3 H2SO4

STRONG BASES—DISSOCIATE 100%All Alkali Metals (IA) form strong

bases

VIII. Weak Acids and Bases

WEAK ACIDS—DO NOT DISSOCIATE 100 %

WEAK BASES—DO NOT DISSOCIATE 100%

How would a weak acid conduct electricity compared to a strong acid?

IX. Polyprotic Acids

Acids with more than one proton (H+)

A. Examples

H2SO4 H3AsO4 H3PO4 H2CO3 H2S

B. Step – By – Step Ionization

Acids lose one proton at a time

1st H3PO4

2nd H2PO4-

3rd HPO4-2

H3PO4 3H+ + PO43-

H+ + H2PO4-

H+ + HPO4-2

H+ + PO4-3

H3PO4 + H2O 3 H3O+ + PO43-3

Questions1. Which of the following are polyprotic

acids?a) HCl d) HC2H3O2

b) NH3 e) H3PO4

c) H2SO4 f) HNO3

2. Which acid is harder to ionize: H3PO4 or HPO4

-2? Why?The -2 charge attracts protons (H+)

3. Which acid is stronger: H2SO4 or HSO4-?

Why?easier to lose protons (H+)

Lab 50 Answers

Water as an acid and a base

amphoteric:

water behaves as an acid & base

H2O + H2O H3O+ + OH-

acid base conj conj

acid base

X. Anhydrides

Without water

Acidic Anhydrides—non-metallic oxides that combine with H2O to form an acid

SO2 + H2O H2SO3

CO2 + H2O

Acid Anhydrides

H2CO3

Basic Anhydrides—metal oxides that combine with H2O to form a base

CaO + H2O Ca(OH)2

Na2O + H2O

Basic Anhydrides

2 NaOH

Try These: Acidic or Basic Anhydride?

K2O

Basic Anhydride

NO2

Acidic Anhydride

http://www.epa.gov/maia/images/acid.jpg

Acid, Bases, and Salts

Chemistry—Part 2

I. Molarity

Example: 6 KOH 0.1 H2SO4 2 NaCl

A measure of concentration

solution

moles #

LM

M M M

Concentration

6 M 1 M

Examples

3 M HNO3 =

solution L 1

HNO moles 3 3

ML

moles4

5

20

20 moles in 5 L = ? M

Try This!

If 80 grams of NaOH (MW=40) is dissolved in 2 L, find the molarity.

molesmolg

g2

/40

80 M

L

moles1

2

2

6 moles of HBr in 250 ml. Molarity?

Mxml

xmoles

ml

moles24

1000250

6

Now Try This One!

How many moles of HCl are in 500 ml of a 3 M solution?

molesxL

xmolesM

L

molesM

5.15.0

3

II. Titration

Using a solution of to determine the concentration of another solution.

A neutralization reactionAcid + Base

known concentration

Salt + Water

End Point

The point at which neutralization is complete

moles H+ = moles OH-

use (like phenolphthalein) to determine the end point

acid-base indicators

Acidic—before neutralization

Neutral—”End Point”

Basic—“overshot endpoint”

NaOH

HCl

H2SO4

1 M 1 M

1 M1 M

50 ml

50 ml

1 M 2 M25 ml

Na+ + OH-

H+ + Cl-

2 H+ + SO42-

NaOH Na+ + OH-

HCl H+ + Cl-

1 M 1 M

2 M2 M

50 ml

25 ml

Titration Equation

OHBBHAA VMVM # #

MA = Molarity of AcidVA = Volume of Acid#H+= Number of H’s in acid formula

MB = Molarity of BaseVB = Volume of Base#OH- = Number of OH’s in base formula

UNITS MUST MATCH!!!

Try This

50 ml of 0.1 M NaOH is neutralized by 5 ml of HCl. Find the molarity of the acid.

MM

OHmlMHmlM

VMVM

A

A

OHBBHAA

1

)1)(50)(1.0()1)(5)((

# #

(5ml)(1H+) (5ml)(1H+)

Try This

40 ml of 1M KOH is neutralized by 10 ml of sulfuric acid. Find the molarity of acid.

MM

OHmlMHmlM

VMVM

A

A

OHBBHAA

2

)1)(40)(1()2)(10)((

# #

(10ml)(2H+) (10ml)(2H+)

III. IndicatorsWeak organic acids or bases that are a

different color in an acid than in a base

Ex:PhenolpthaleinBromothymol BlueLitmusRed Cabbage

Limitations of Indicators

Solutions must be colorless

Eye must be able to detect the change

IV. Ionization of Water

In pure water, [H+] = 10-7 M and [OH-] = 10-7 M

1 water out of 10,000,000 forms ions

[ ] stands for concentration

Kw – water’s ionization constant

Kw = [H+] [OH-]

Kw = (10-7) (10-7)

Kw = 10-14

so…

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

CONSTANT

Add Acid? Add Base?

Example #1

[OH-] = 10-6 M [H+] = ?

MH

H

OHHKw

8

614

10][

]10][[10

]][[

Example #2

[H+] = 10-3 M [OH-] = ?

MOH

OH

OHHKw

11

314

10][

]][10[10

]][[

pH Scale

Used to measure acidity

Based on the concentration of H+ ions

When the [H+] increases by 10, the pH decreases by 1.

When the pH increases by 2, the [H+] decreases by _____102 = 100

pH = -log[H+]

[H+] = 10-4 pH = ______ acidic or basic?

[H+] = 10-11 pH = ______ acidic or basic?

4

11

pOH = -log[OH+]

[OH-] = 10-3 pOH = ______

[H+] = 10-9 pOH = ______

3

5

pH + pOH = 14

Why?[H+] [OH-] = 10-14

(10-7) (10-7) = 10-14

pH + pOH = 14

- log - log

Try These:For a solution that is 0.1 M HCl…1) What is the pH?2) What is the concentration of OH- ions?3) What is the pOH?For a solution that is 0.001 M NaOH…4) What is the pOH?5) What is the pH?6) What is [H+]?For a solution that has a pH of 8…7) What is the [H+]?

Hydrolysis

The reaction of a salt with water to form an acidic or basic solution

Recall Strong Acids:

Recall Strong Bases:

HCl HNO3 H2SO4

Group IA Hydroxides

Look at the Parent Acid & Parent Base

Salt Parent Acid Parent Base

Neutral STRONG STRONG

Acidic STRONG weak

Basic weak STRONG

Ex: NaF

Parent Acid:

Parent Base:

So…NaF is BASIC

HF

NaOH

strong or weak?

strong or weak?

Try This: Fe(NO3)3

Parent Acid:

Parent Base:

So…Fe(NO3)3 is ACIDIC

HNO3

Fe(OH)3

strong or weak?

strong or weak?

Try This: NaCl

Parent Acid:

Parent Base:

So…NaCl is NEUTRAL

HCl

NaOH

strong or weak?

strong or weak?