1

What is

chemistry?

Chemistry

2

What is Chemistry? CuCl2 + NH3 What happens?

CuCl2 soluble

Cu(OH)2(s) insoluble

Cu(NH3)4+2

soluble

3

Molecular

Interpretation

Cu+2 +2OH- Cu(OH)2

This course: understand & predict

Cu(OH)2 + 4NH3

Cu(NH3)4+2 + 2OH-

NH3 + H2O NH4+ + OH-

4

Chemistry

•the study of matter

•and the changes

matter undergoes

Focus:

•Underlying principles

•Molecular point-of-view

5

Classification of Matter

?? H2, cement, air, NaCl

Homo-geneous

Hetero-geneous

Mixture

Cmpd Element

Substance

Matter

“solution”

Physically

Separate

Chem. Separate.

Give examples of physical separation & chemical separation

Physical vs. Chemical Change

6

Physical change: no new substance is formed. e.g. melt, bend, cut, boil

Chemical change: new substance formed (always involves a chemical reaction).

e.g. Fe(s) + S(s) FeS(s)

7

Units of Measurement

Quantity SI Unit Others

Length m cm

Mass kg g

Time s

Temperature K oC

Metric Prefixes (know them!)

8

giga- G E9 mega- M E6 kilo- k E3 deci- d E-1 centi- c E-2 milli- m E-3 nano- n E-9 pico- p E-12

How many grams is 14 pg?

9

Derived Units

How many cm3 in 1 m3 ?

For example: volume

10

Derived Units

Density = mass/volume

What is the mass of 17.4 mL

of ethanol (D = 0.798 g/mL)?

1 g H2O @ 4oC = 1 cm3 = 1mL

11

Temperature Scales

Kelvin

0

273

373

(Size of

degree is

the same)

Celsius

Motion

stops -273

Water freezes

Water boils 100

0

12

Temperature Scales

K = oC + 273.15

Try it:

1. 72oC = ? K

2. What is room temperature in oC?

3. If T changes by 37oC, what is

the change in Kelvin?

13

Scientific Notation Avogadro’s Number:

602,200,000,000,000,000,000,000

6.022 x 1023 particles

Mass of H atom:

0.00000000000000000000000166 g

1.66 x 10-24 g

14

Using Scientific Notation

N. x 10n

Add/subtract: n must be the same

Add 7.4 x 103 and 2.1 x 102

Multiply (divide): add (subtract) n’s

Divide 8.0 x 102 by 6.2 x 104

15

Significant Figures

•All non-zeros are sig. 1.234 ? •Zeros between non-zeros are sig. 40,501 ?

How wide is this room?

16

Significant Figures

Zeros to left are NOT sig. 0.000349 ?

Zeros to right are sig. if there is a decimal point. 0.09030 ? 400 ?

17

Sig Figs in Calculations

Add/subtract: answer has same number of digits to right of decimal as the number with the fewest digits to right of decimal.

89.321 + 9.2 =

18

Sig Figs in Calculations

Multiplication/division: answer has the same number of sig figs as the number with least number of sig figs.

2.8 x 4.5039 =

19

Pure Numbers

How many sig figs in:

Five people?

2.54 cm = 1 in

20

Conversion Factors

5 apples = $1.00

5 apples $1.00

= 1

In Wegman’s, apples cost 5 for a dollar.

21

Conversion Factor

5 apples = 1 dollar

1 dollar = 100 pennies

10-2 m = 1 cm (or 1 m = 100 cm )

1 mole = 6.02 x 1023 atoms

1 g H2O = 1 mL H2O

22

Conversion Factors: Try it.

Convert radius of Ca atom (0.197 nm) to cm. (Hint: go through the base unit.)

Adult has 5.2 L of blood. What is volume in m3 ?

What is 65 miles per hour (mph) in m/s ? (1609 m = 1 mi)

23

Atoms, Molecules, Ions

Early chemists study the first known atom.

24

Atomic Theory

Democritus vs. Dalton

500 BC 1808 AD

Pure

thought

Observation

+ Reason

Matter is not continuous!! Weird.

25

Dalton’s Atomic Theory

Elements composed of atoms

Atoms of element are identical*

Compounds: simple integers of

atoms

Chem Rxn: rearrangement, not

creation, of atoms

26

Dalton’s Theory

Law of Definite Proportions:

(mass of C and O in CO2)

Law of Multiple Proportions:

(CO and CO2)

Based on observations:

27

Subatomic Particles

The Electron

28

The Electron

Symbol: e-

Charge = -1 = -1.6 x 10-19C

Mass = 9.09 x 10-28 g

29

The Proton

Ernest

Rutherford

1910

30

The Proton

Charge = +1

Mass = 1.67 x 10–24 g

31

The Neutron

Mass ratio of He/H problem

Chadwick 1932

(nuclear chemistry)

Charge = 0

Mass = 1.67 x 10–24 g

(similar to proton)

32

Relative Proportions

Protons &

Neutrons

Electron cloud

33

Atomic Number & Mass Number

Mass number

(#p + #n)

Atomic number

(#p)

X A

Z

H 1

1 H

2

1 H

3

1

34

Practice

How many p, n, e- in:

Hg ? 200

80

-2 ion of Oxygen-16 ?

Hg-200 or

35

Periodic Table

36

Periodic Table

Group/Family vs. Period

Metals/Nonmetals/Metalloids

Key Groups

1 or 1A: Alkali Metals

2 or 2A: Alkaline Earth Metals

17 or 7A: Halogens

18 or 8A: Noble Gases

37

Atoms, Molecules, Ions

Water Ammonia Methane

38

Systematic Names: Why?

Common Name Formula

Water H2O

Lime CaO

Lye NaOH

Potash K2CO3

Laughing Gas N2O

Baking Soda NaHCO3

Muriatic Acid HCl

39

Chemical Formulas

Molecular formula: Exact

numbers of atoms of each

element in a molecule.

Cl

H

C Chloroform

CHCl3

40

Chemical Formulas Empirical: smallest whole number

ratio of atoms in a compound.

Glucose: C6H12O6 CH2O

Hydrogen Peroxide: H2O2 HO

41

Molecular Compounds

Molecular cmpds: bonded nonmetals

Many molecular compounds

are binary (only 2 elements)

ending in ---ide.

HCl = hydrogen chloride

Organic compounds have a special naming system.

42

Molecular Compounds

Name is:

prefix-atom-prefix-atom-ide mono 1

di 2

tri 3

tetra 4

penta 5

hexa 6

N2O dinitrogen monoxide

PCl3 phosphorus trichloride

43

Molecular Compounds

SiCl4

AlCl3

H2O NH3 H2S

Try it!

44

Ionic Compounds

Ionic Compounds: usually

a positive metal ion +

negative nonmetal ion.

Binary: NaCl = sodium chloride

Ternary: BaCO3 = barium carbonate

45

Ions Ion: Charged atom or group of

atoms (monatomic or

polyatomic; Cl- vs CO3-2)

chlorine atom: 17 p & 17 e-

chloride ion: 17 p & 18 e-

Cation: +positive Anion: -negative

46

Ionic Formulas

Sum of charges is zero.

e.g. Aluminum Oxide

Al2O3

“criss-cross”

2(+3) + 3(-2) = 0

Al3+ O2-

47

Ionic Formulas Ionic compounds always use

empirical formulas.

Sodium Chloride: NaCl

Polyatomic Ions (know them!)

48

Memorize the ‘ate’ Ions

49

ate: C2H3O2

- CO32- C2O4

2-

ClO3- CrO4

2- Cr2O72-

MnO4- NO3

- PO43-

SCN- SO42- S2O3

2-

Rule: if the non-oxygen atom is in an odd Group, charge is -1 (except PO4

3-)

Figure Out the ‘hydrogen ---ate’ ions

50

CO32-

HCO3-

SO42- HSO4

-

Adding a hydrogen decreases the charge by 1.

Figure Out ‘ite’ ions

51

ClO4- perchlorate 1 more O

ClO3- know the ‘ate’

ClO2- chlorite 1 less O

ClO- hypochlorite 2 less O

Try it: name IO2-

Memorize Some Others

52

H3O+ Hg2

2+ NH4+

CN- O22- OH-

Have fun!

53

Ionic Compounds

Some metals form

more than one cation:

Fe+2 Fe+3

Classical Ferrous Ferric

Stock Iron(II) Iron(III)

FeCl3 = Iron(III) chloride

Common Metals with more than one charge (know them!)

54

Cu+ copper(I) Sn2+ tin(II)

Cu2+ copper(II) Sn4+ tin(IV)

Fe2+ iron(II) Hg22+ mercury(I)

Fe3+ iron(III) Hg2+ mercury(II)

Pb2+ lead(II) Au+ gold(I)

Pb4+ lead(IV) Au3+ gold(III)

55

Practice

NH4ClO3 calcium phosphate

PbO

cupric sulfite

iron(III) carbonate

56

Naming Acids

Acid: substance yielding

H+ (proton) in water.

HCl = hydrogen chloride

HCl(aq) = hydrochloric acid

57

Naming Acids

58

Binary Acids

Anion Example

_ide Chloride Cl-

Acid Example

hydro_ic acid hydrochloric acid

HCl

59

Oxyacids

Anion Example

_ite chlorite ClO2-

Acid Example

_ous acid chlorous acid

HClO2

60

Oxyacids

Anion Example

_ate chlorate ClO3-

Acid Example

_ic acid chloric acid

HClO3

61

Naming Acids

Anion Acid chloride HCl hydrochloric acid

hypochlorite HClO hypochlorous acid

chlorite HClO2 chlorous acid

chlorate HClO3 chloric acid

perchlorate HClO4 perchloric acid

62

Acids: Try It !!!

H2SO4

HF

HNO3

HCN

H2SO3

63

Have Some Fun

Read about naming bases,

and hydrates on your own.

Quiz on compound names and formulas.

64

Mass Relationships in Chemical Reactions

The Mole

I

RULE !!!

65

Masses (not weights)

• proton = 1.673 x 10-24 g

• neutron = 1.675 x 10-24 g

• electron = 9.109 x 10-28 g

66

Atomic Mass Unit

1 amu 1/12 mass of C-12 atom

Mass of C-12 atom 12.00… amu

Mass of H 1 amu mass 1 p

Mass of O 16 amu

67

Average Atomic Mass

Periodic Table lists

weighted-average

atomic mass of the

naturally occurring

isotopes.

Determining Mass and Abundance of Isotopes.

68

Mass Spectrometry or Mass Spectroscopy

ion detector

vacuum pump

accel. field

ionizing e- beam

injection

Mass Spectrometry

69

1. Substance injected into vacuum tube. 2. Particles are ionized by e- beam. 3. Ionized particles are accelerated in elec. field. 4. Particles are deflected by magnetic field

that can be varied in strength. 5. Deflection depends on particle mass-to-

charge ratio, particle speed, and magnetic field strength.

6. Particles enter ion detector.

Strontium Example

70

Relative peak heights: • Sr-84 0.68 • Sr-86 12.00 • Sr-87 8.47 • Sr-88 100.00 Total 121.15

Strontium Weighted Average

71

.68 121.15

x 84.0 amu = 0.47 amu

12.00 121.15

x 86.0 amu = 8.52 amu

8.47 121.15

x 87.0 amu = 6.08 amu

100.00 121.15

x 88.0 amu = 72.64 amu

87.71 amu

Fractional abundance

72

Average Atomic Mass

e.g. Chlorine has 2 isotopes:

75.77% Cl-35 @34.969 amu

24.23% Cl-37 @36.966 amu

(.7577)(34.969 amu) +

(.2423)(36.966 amu) = 35.453 amu

73

Average Atomic Mass TRY IT: Of every 100 atoms of

Cu, 69.09 are Cu-63 (62.93 amu)

and the rest are Cu-65 (64.93

amu). Calculate the mass of Cu

as given on the Periodic Table.

74

Molecular Mass

The sum of atomic masses in amu

Molecular mass of HNO3:

H: 1 x 1.008 amu = 1.008 amu

N: 1 x 14.01 amu = 14.01 amu

O: 3 x 16.00 amu = 48.00 amu

= 63.02 amu

TRY IT: What is mass of N2O4?

75

The Mole

Mole:

number of C atoms in

exactly 12 g of C-12.

“chemist’s dozen”

76

Avogadro’s Number

1 mole =

6.022 x 1023 particles

77

Avogadro’s Number

602,204,500,000,000,000,000,000 # of grains of sand in the world!

# of stars in the universe!

78

The Mole

1 mole C atoms = 6.02 x 1023 atoms

1 mole CO2 molecules = 6.02 x 1023

molecules

1 mole pencils = 6.02 x 1023 pencils

1 mole Br- ions = 6.02 x 1023 ions

79

Molar Mass

Molar Mass

mass (in g) of one mole

e.g. 1 mol C atoms

= 6.02 x 1023 atoms C

= 12.0 g C

80

(6 x 12.0 g) + (12 x 1.0 g) + (6 x 16.0 g)

= 180.0 g

Mass of one mole of glucose,

C6H12O6

Molar Mass

81

Molar Mass: Other Terms

Gram atomic mass:

gam of Fe is 55.9 g

Gram molecular mass:

gmm of CO2 is 44.0 g

Gram formula mass:

gfm of NaCl is 58.4 g

82

Molar Mass

Mass (g) # Particles

Molar mass

g/mol

6.02 x 1023

part./mol Moles

Conversion Factors

83

Mole Practice

What is mass in g of one C-12 atom?

How many grams in one amu? (Hint: use carbon as an example.)

What is the molar mass of C6H8O6 ?

How many H atoms in 25.6 g urea?

(NH2)2CO

84

Percent Composition

% by mass of each element in a cmpd

= n x molar mass of element

molar mass of cmpd X 100

where n = element subscript

CO2

85

Percent Composition

What is % of O in CO2?

= n x molar mass of element

molar mass of cmpd X 100 %O

= 2 x 16.00

44.01 X 100

= 72.71%

86

Percent Composition

What is the mass of Cu (in kg)

in 3.71 x 103 kg of

chalcopyrite (CuFeS2)?

TRY IT !!

87

Percent Composition

If % composition is known,

a compound’s empirical formula

can be determined.

88

Empirical Formula

What is empirical formula of compound:

24.75% K 34.77% Mn 40.51% O?

Divide by smallest number KMnO4

assume 100 g

24.75 g 34.77 g 40.51g

.6330 mol .6330 mol 2.532 mol

go to moles

89

Empirical Formula

Sometimes it is not so easy!

What is emp. formula of Vitamin C?

C = 40.92%

H = 4.58%

O = 54.50%

Try it.

90

Empirical Formulas of C-H-O Compounds

Heat

O2

H2O CO2 absorber absorber

Sample

91

Example

If combustion of an 11.5 g sample

of ethanol produced 22.0 g of CO2

and 13.5 g of H2O, what is the

empirical formula of ethanol?

Try It

92

If combustion of a 21.4 g sample

of an unknown C-H-O compound

produced 29.5 g of CO2 and 24.1 g

of H2O, what is the empirical

formula of the compound?

93

Molecular Formulas

If the empirical formula and

approximate molar mass are

known, molecular formula can

be determined.

94

Molecular Formulas

Problem: A compound contains

only 1.52 g N and 3.47 g O and

has molar mass 95. What is it’s

molecular formula?

95

Molecular Formulas

N: 1.52 g 0.108 mol

O: 3.47 g 0.217 mol NO2

NO2 has empirical molar mass of

46.02 g compared to molar mass 95 g.

Molar mass

Emp.mol.mass = 95 g

46.02 g N2O4

96

Molecular Formulas

Problem: 200 g of a compound

contains 77.34 g C, 32.44 g H and

90.22 g N and has molar mass .

What is it’s molecular formula?

TRY IT !!

97

Chemical Equations

Chemical Reaction:

Atoms & molecules

react to form

new substances.

A chemical reaction is represented

by a chemical equation.

98

Evidence of Reactions

• Macroscopic evidence of chemical

reactions:

Heat Light

Gas Solid (precipitate)

Color change

• Chemical change involves creation of

new substances with new properties,

usually accompanied by a noticeable

energy change.

99

Chemical Equations

H2 + O2 H2O

But mass must be conserved!

Hydrogen burns to form water.

100

Chemical Equations

Balanced: 2H2 + O2 2H2O

Also show state:

2H2 (g) + O2 (g) 2H2O (l)

2H2 O2 2H2O

+

101

Balancing Equations

Identify reactants & products

Write correct formulas first

Change only coefficients

2H2 + 1O2 2H2O

Double check

102

Balancing Equations

Potassium chlorate decomposes

upon heating to yield oxygen

and potassium chloride:

KClO3 KCl + O2 3 2 2

103

Balancing Equations

Complete combustion of

Ethane (C2H6) yields carbon

dioxide and water.

Try it.

104

Types of Reactions

• Combination

• Decomposition

• Single Replacement

• Double Replacement

• Combustion

105

Combination

2 Br2 + 2 NaBr Na

106

Decomposition

CaCO3 CaO + CO2

107

Single Replacement

Cu AgNO3 2 Cu(NO3)2 2 + Ag

Cu + ZnCl2 No Reaction

+

108

Double Replacement

BaCl2 + H2SO4 2 BaSO4 + HCl

3 CrCl3(aq) + NaOH(aq)

3 Cr(OH)3(s) + NaCl(aq)

Soluble Ionic Compounds

109

Ionic compounds that are soluble in

water actually exist as separated ions.

CrCl3(aq) is actually:

Cr+3(aq) + 3Cl-(aq)

Net Ionic Equations

110

CrCl3(aq) + 3NaOH(aq)

Written as a net ionic equation is:

Cr(OH)3(s) + 3NaCl(aq)

Cr3+(aq) + 3 OH-(aq) Cr(OH)3(s)

Cl- and Na+ are “spectator ions”

111

Combustion

C2H5OH + 3 O2 2 CO2 + 3 H2O

112

Stoichiometry

The quantitative study of reactants

and products in a chemical reaction.

Interpret coefficients in chemical

equation as molecules or moles.

2H2 + O2 2H2O

2 mol H2 + 1 mol O2 2 mol H2O

113

Stoichiometry

2H2 + O2 2H2O

2 mol H2 1 mol O2 2 mol H2O

means stoichiometrically

equivalent to

114

Stoichiometry

2Li + 2H2O 2LiOH + H2

How many moles of H2 are

obtained from complete

reaction of 6.23 moles of Li ?

6.23 mol Li 1 mol H2 = 3.12 mol H2 x 2 mol Li

115

Stoichiometry

2Li + 2H2O 2LiOH + H2

How many g H2 from 81 g Li ?

81 g Li 1 mol Li 6.9 g Li

1 mol H2 2 mol Li

2.0 g H2 1 mol H2

= 12 g H2

x x

x

116

Stoichiometry

You try it! A key reaction in smog formation is:

2NO + O2 2NO2 1. How many g NO2 formed by

complete reaction of 1.44 g NO ?

2. How many molecules of NO2

formed from 0.00052 mg of NO ?

117

Limiting Reagents

How many cheese sandwiches

can be made from:

25 slices of cheese

12 tomatoes

7 heads of lettuce

4 slices of bread

Bread is the “limiting reagent”

118

Burn S in F2: S + 3F2 SF6

What if 4 mol S added to 20 mol F2 ?

Since 1 mol S 3 mol F2

Then 4 mol S 12 mol F2

Thus S is limiting and F2 is excess.

Limiting Reagents

119

Limiting Reagents

Urea is made by reacting

ammonia and carbon dioxide:

2NH3 + CO2 (NH2)2CO + H2O

If 641 g NH3 reacts with 1140 g CO2 •Which chemical is limiting ?

•How much urea is formed ?

•How many g of excess reagent is left ?

120

2NH3 + CO2 (NH2)2CO + H2O

641 g 1140 g

Start with NH3 & convert to urea:

641 g NH3 1 mol NH3 17.0 g NH3 2 mol NH3

1 mol urea

1 mol NH3

60.1 g urea = 1130 g urea

x x

x

121

2NH3 + CO2 (NH2)2CO + H2O

641 g 1140 g

Start with CO2 & convert to urea:

1140 g CO2 1 mol CO2 44.0 g CO2 1 mol CO2

1 mol urea

1 mol urea 60.1 g urea = 1560 g urea

x x

x

1130 g

122

2NH3 + CO2 (NH2)2CO + H2O

641 g 1140 g

1130 g

1560 g

Since NH3 yields less urea, it is

the limiting reagent, and 1130 g

urea will be produced.

CO2 is the excess reagent.

123

To calculate the excess amount of

CO2, start with limiting reagent, NH3.

641 g NH3 1 mol NH3 17.0 g NH3 2 mol NH3

1 mol CO2

1 mol CO2 44.0 g CO2

= 829 g CO2

2NH3 + CO2 (NH2)2CO + H2O

1140 g – 829 g = 311g excess CO2

x x

x

124

Limiting Reagents

You try one!

Al reacts with iron(III) oxide highly

exothermically. If 124 g Al reacts with

601 g iron(III) oxide:

•Write a balanced equation.

•How much aluminum oxide is formed ?

•How much excess reagent is left ?

125

Reaction Yield

from limiting reagent calculation

from experiment

% Yield = Actual Yield

Theoretical Yield x 100%

126

Reaction Yield Ammonia is produced by the Haber

process by reacting nitrogen gas and

hydrogen gas:

N2 + 3H2 2NH3

What is the % yield if 254 g NH3

are produced by reacting 246 g of N2 with 62 g of H2 ?

127

N2 + 3H2 2NH3 246 g 62 g 254 g

1. Determine limiting reagent

246 g N2 28.0 g N2

1 mol N2

1 mol N2

3 mol H2

2.02 g H2

1 mol H2 = 53.2 g H2

Thus N2 is the limiting reagent.

x x

x

128

2. Calculate theoretical yield of NH3

246 g N2 28.0 g N2

1 mol N2 1 mol N2

2 mol NH3

17.0 g NH3

1 mol NH3 = 299 g NH3

limiting

N2 + 3H2 2NH3 246 g 62 g 254 g

x x

x

129

3. Calculate % yield of NH3

vs.

299 g theo.

= 254 g

299 g x 100%

= 85.0 % yield

N2 + 3H2 2NH3 246 g 62 g 254 g

% Yield = Actual Yield

Theoretical Yield x 100%

130

TRY IT !!

Methanol is made by reacting hydrogen

gas and carbon monoxide gas.

Write balanced equation.

Calculate the % yield if 3.57 x 104 g of

CH3OH is produced by reacting 68.5 kg

carbon monoxide and 8.60 kg hydrogen.

131

Warm-up

132

What is 65 miles per hour in m/s?

Warm-up

133

Read the volume in the graduated cylinder.

Warm-up

134

The density of aluminum is 2.7g/mL.

What is its density in kg/m3?

Warm-up

135

Name or give formula:

Cl2O lithium nitride KMnO4 strontium phosphite NH3 AuSCN Hg2(NO3)2 Cu2O

Warm-up

136

Name or give formula:

HCN(aq) SnCl4

carbonic acid N2O4

magnesium nitride AlI3

Warm-up

137

What is the mass in grams of one water molecule?

Warm-up

138

83 g of a compound contains 36 g phosphorous, the remainder being oxygen. Its molar mass is 280 g/mol. What is its molecular formula?

Warm-up

139

For the reaction:

CH4(g) + 2O2(g) CO2(g) + 2H2O(l)

How many mL of water is produced by burning 17g CH4 in excess O2?

Warm-up

140

N2 is prepared by passing ammonia over solid copper(II)oxide. If 18.1 g NH3 reacts with 90.4 g copper(II)oxide, how many grams of N2 are formed?

2NH3(g) + 3CuO(s)

N2(g) +3Cu(s) + 3H2O(g)

Lab 2: Empirical Formula CuI or CuI2?

141

Beaker + clean Cu strip 56.1065 g

Beaker + CuxIy product 56.1245 g

Beaker after removing CuxIy 56.0978 g

• How do you determine mass iodine? • How do you determine mass copper?