chem 101-01

8/2/2019 Chem 101-01

1/28

08-Sep-

Chemistry: The Central

Science

Dr. A. Al-Saadi 1

Everything in this universe is made out of

Chapter 1 Section 1

Why Chemistry?

.

Sand (Silicon, Oxygen)

Table Salt (Sodium, Chloride)

Water (Oxygen, Hydrogen)

They are as letters in an alphabet.

Dr. A. Al-Saadi 2

8/2/2019 Chem 101-01

2/28

08-Sep-

Chapter 1 Section 1

Why Chemistry?

Dr. A. Al-Saadi 3

Chemical reactions are very common in

Chapter 1 Section 1

Why Chemistry?

s e an are mpor an or our surv va

on the Earth.

They also cause many problems for

humanity!

Dr. A. Al-Saadi 4

chemical reactions?

8/2/2019 Chem 101-01

3/28

08-Sep-

Scientific Method

Chapter 1 Section 1

The scientific method is the way used

b scientists to understand the universe

and its changes.

The more creative youre at solving

problems, the more effective you will be

in your career and your personal life.

Chemistr hel s to develo solvin

Dr. A. Al-Saadi 5

problems capabilities.

Scientific Method

To understand the universe and its

chan es.

Chapter 1 Section 1

Steps of scientific methods:

Observation.

Can be qualitative orquantitative.

Prediction (Hypothesis).

Tr in to ex lain the observation.

Dr. A. Al-Saadi 6

Experiment.

Performed to test the validity of the hypothesis.

Experiments always produce new information.

8/2/2019 Chem 101-01

4/28

08-Sep-

Scientific Method

Chapter 1 Section 1

se o va ypo eses s

assembled into a theory (model).

This theory is confirmed, modified

or may be discarded as more

observations are recorded. Thus, it is

Dr. A. Al-Saadi 7

.

Theory vs. Law

Chapter 1 Section 1

Theory changes over time as more

observations from experiments are recorded.

Some observations are found to apply to

many different systems.

Law (what happens)

A summary of observed behaviors applied to

different systems.

Dr. A. Al-Saadi 8

aw o conserva on o mass. Law of conservation of energy.

Theory (why it happens)

An attempt to explain these observations.

8/2/2019 Chem 101-01

5/28

08-Sep-

Scientific Method

Chapter 1 Section 1

Dr. A. Al-Saadi 9

Classification of Matter

Matter is anything occupying the space

Chapter 1 Section 2

.

Matter can be:

Asubstance is a form of matter that

has a defined composition and unique

ro erties.

Dr. A. Al-Saadi 10

Amixture is a combination of two or

more substances that retain their

distinct identities.

8/2/2019 Chem 101-01

6/28

08-Sep-


Chapter 1 Section 2

Dr. A. Al-Saadi 11

States of matter: Solid: rigid, has fixed volume and shape.

Liquid: has definite volume but not fixed shape.

Gas: has no fixed volume or shape. and is compressible.


Chapter 1 Section 2

Dr. A. Al-Saadi 12

oo Sand

Rocks

Juices and tea

Air (N2, O2, H2,

CO2, etc.) H2O

NaCl

H2SO4

C (carbon)

Hg (mercury)

H or H2(hydrogen)

8/2/2019 Chem 101-01

7/28

08-Sep-

Separation (Physical) Methods

Based on the physical properties of the substances

Chapter 1 Section 2

, , , .

Separation methods discussed in the text:

Distillation.

Filtration.

Chromatography.

Dr. A. Al-Saadi 13

Elements and Compounds

Elementsare substances thatcant be decomposed into

Chapter 1 Section 2

Compoundsare substanceswith constant compositionthat can be broken down intoelements by chemicalprocesses

physical or chemical means

Dr. A. Al-Saadi 14

Chemical changes(decomposition of compoundsor recombining elements),such as electrolysis, heating,and photolysis.

8/2/2019 Chem 101-01

8/28

08-Sep-


Classify the following as mixtures, elements,

compounds, etc.

Chapter 1 Section 2

Aluminum foil:

substance, element

Table salt:

substance, compound

Milk:

Dr. A. Al-Saadi 15

mixture, homogeneous

Sea water:mixture, homogeneous

Copper wire:

substance, element

The Properties of Matter

Quantitative: expressed using numbers.

Chapter 1 Section 4

.

Physical properties: can be observed and

measured without changing the substance.

Examples: color, melting point, states of matter.

Dr. A. Al-Saadi 16

substance stays the same and only its state

changes.

Examples: changes of state (melting, freezing).

8/2/2019 Chem 101-01

9/28

08-Sep-


Chemical properties: must be determined by

Chapter 1 Section 4

.

Examples: flammability, acidity, corrosiveness,

reactivity.

Chemical changes: after a chemical change,

the original substance no longer exists

Dr. A. Al-Saadi 17

Examples: combustion, digestion, corrosion.


Extensive property:de ends on the

Chapter 1 Section 4

amount of matter.

Examples: mass,length.

Intensive property:Mass of water 100.0 10.0

Dr. A. Al-Saadi 18

the amount ofmatter.

Examples: density,temperature, color.

Volume of water 0.100 L 0.010 L

Temperature of water 25 C 25 C

Density of water 1.00 g/mL 1.00 g/mL

8/2/2019 Chem 101-01

10/28

08-Sep-

Scientific Measurement

Chapter 1 Section 3

Making observations can be done quantitatively or

ualitativel .

Number Unit

A quantitative observation is called a measurement. It

must include two important pieces of information:

Dr. A. Al-Saadi 19

(1) Metric

Units

International

System (SI

Units)

(2) English

Units

Used in

Science

There are twomajor systems of

measurements:

The Fundamental SI Units

Chapter 1 Section 3

Dr. A. Al-Saadi 20

All other units of measurement can be derived from

the above seven fundamental SI units .

8/2/2019 Chem 101-01

11/28

08-Sep-

Units of Measurement

Chapter 1 Section 3

Number UnitThere are two

major systems of

10 kilometers

1 gram

5 kelvin

(1) Metric

Units

International

System (SI

Units)

Used in

measurements:

Dr. A. Al-Saadi 21

20 miles

1 pound

60 Fahrenheit

(2) English

Units

c ence

Using Prefixes in the SI System

The distance between

Chapter 1 Section 3

,

meters.

90103 meters.

90 kilo-meters (km)

The ca acit of this com uter

Dr. A. Al-Saadi 22

is 80,000,000,000 bites.

80109bites

80 giga-bites (GB)

8/2/2019 Chem 101-01

12/28

08-Sep-

Table of Prefixes in the SI System

Chapter 1 Section 3

Dr. A. Al-Saadi 23Must be memorized!

Scientific Notation

0.0001 kg-4

Chapter 1 Section 3

0.1 g

1 with 35 zeros kg

How much does that pin weigh?Scientific Notation

Dr. A. Al-Saadi 24

Mass vs. Weight

How much does the earth weigh?

8/2/2019 Chem 101-01

13/28

08-Sep-

Scientific Notations

123.1 = 1.231 102 = 1.231 100

0.00013 = 1.3 10-4 = 1.3 / 10000

Chapter 1 Section 3

= 0.13 10-3

Avogadros Number*:

602,214,000,000,000,000,000,000*The number of atoms contained in 12 g of carbon and is equal to 1 mole.

Dr. A. Al-Saadi 25

6.022 10

23

Scientific notation is a very convenient way to

express the number of atoms in chemistry problems.

Temperature

Three systems are used to measure

Chapter 1 Section 3

Celsius scale (C)

Kelvin scale (K)

Fahrenheit (F)

Dr. A. Al-Saadi 26

You have to be able to convert from one

scale to another.

8/2/2019 Chem 101-01

14/28

08-Sep-

The Three Major Temperature Scales

Chapter 1 Section 3

Fahrenheit (F) Celsius (oC) Kelvin (K)

Dr. A. Al-Saadi 27

Celsius Scale vs. Kelvin Scale

Temperature scales

Chapter 1 Section 3

identical, but their

zeros are different.

TK= TC + 273.15

Dr. A. Al-Saadi 28

TC = TK 273.15

8/2/2019 Chem 101-01

15/28

08-Sep-

Fahrenheit Scale vs. Celsius Scale

Both unit temperature

Chapter 1 Section 3

are different.

Since:

180F = 100C => 9F = 5C

and:

32F = 0C

Dr. A. Al-Saadi 29

Then to convert from F to C:

[Tf (F) 32 (F)] = Tc (C)

5C

9F

Volume

Volume is not an SI unit, but it is

extremely important in chemical

Chapter 1 Section 3

measurements.

Volume = 1m 1m 1m = 1m3

1m = 10dm

(1m)3 = (10dm)3

1m3 = 1000dm3

Dr. A. Al-Saadi 30

m =1L = 1000mL = 1000cm3

1mL = 1cm3

(milli)Liter milli = 10-3

(centi)Meter centi = 10-2

8/2/2019 Chem 101-01

16/28

08-Sep-

Measurement of Volume

Chapter 1 Section 3

Dr. A. Al-Saadi 31

Common types of laboratory equipment used to

measure liquid volume.

Density

It is the mass of substance massDensity

Chapter 1 Section 3

. vo ume

Substance Physical State Density (g/cm3)

Oxygen Gas 0.00133Hydrogen Gas 0.000084

Dr. A. Al-Saadi 32

.Water Liquid 0.998

Aluminum Solid 1.47Iron Solid 7.87

Mercury Liquid 13.6

8/2/2019 Chem 101-01

17/28

08-Sep-

Uncertainty in Measurement

A measurement always has

Chapter 1 Section 5

some egree o uncerta nty.

20.16 ml

20.17 ml

Uncertainty is

0.01 ml.

Certain and

Dr. A. Al-Saadi 33

20.15 ml

20.18 ml20.16 ml

certaindigit

uncertain digit(must be estimated)

uncertain digits are

known assignificant

figures.

Now you should be able to tell how many

di its ou need to include in our readin


Chapter 1 Section 5

(measurement).

20 ml

20.1 ml

20.16 ml

Which one??

Dr. A. Al-Saadi 34

20.160 ml

20.1600 ml

These meaningful digits are the significant figures

8/2/2019 Chem 101-01

18/28

08-Sep-


Chapter 1 Section 5

2.5 0.1 cm

These meaningfuldigits are the

significant figuresUncertainty

Dr. A. Al-Saadi 35

Different equipments have differentuncertainties in their measurements.

2.46 0.01 cm

Significant Figures

In many cases, important physical quantities are obtained

from measured values.

Chapter 1 Section 5

Volume = l w h

Density = mass / volume

Calculations need to be done on the basis ofSignificantFigure (S.F.) Rules

Mathematicaloperations

Dr. A. Al-Saadi 36

u es or count ng . . Rules of mathematical operations on S.F.

Implication of the word Significant. It is to have the

correct degree of uncertainty in the resultant physical

quantities.

8/2/2019 Chem 101-01

19/28

08-Sep-

Rules for Counting Significant Figures

1- Nonzero integers are always counted as

Chapter 1 Section 5

. .

Example: Give the number of S.F. for the following:

34

236

Dr. A. Al-Saadi 37

17296.1

12.1102 Exponential (Scientific) notation


2- Zeros (leading zeros, captive zeros, and

Chapter 1 Section 5

a) Leading zeros are not counted as S.F.


00121.1

Dr. A. Al-Saadi 38

0.0025

8/2/2019 Chem 101-01

20/28

08-Sep-

2


b) Captive zeros are always counted as S.F.

Chapter 1 Section 5


1.008

701.1 10-4

3.000000008

Dr. A. Al-Saadi 39

0.0901


c) Trailing zeros are counted as S.F. only if the

Chapter 1 Section 5

.


1.000

320.00 10-1

Dr. A. Al-Saadi 40

100 (cant tell!) may be 1, 2 or 3.

100.

100.0

8/2/2019 Chem 101-01

21/28

08-Sep-

2


3- Exact numbers are assumed to have an

Chapter 1 Section 5

. .

Examples:

3 Apples is 3.00000000 (zeros are all the way to)

Dr. A. Al-Saadi 41

n r e c rcum erence o a cyc e .

1 km = 1000 m1 in = 2.54 cm

MathematicalrelationshipsDefinitions

Exercise

How many significant figures are there in the

Chapter 1 Section 5

30045.

10101200 .

m

cm3

Dr. A. Al-Saadi 42

0250. kg

8/2/2019 Chem 101-01

22/28

08-Sep-

2

Mathematical Operations

Multiplication or division

Chapter 1 Section 5

. . = . .

Fromcalculatorbefore

correction

Numberof S.F. 3 2 2 S.F. (After

correction)

Dr. A. Al-Saadi 43

12.11

+ 18.0

+ 1.013 31.1

31.123before

correction

3 S.F. (Aftercorrection)

Rule for Rounding

6.38

Chapter 1 Section 5

The digit to be removed

If 5, then round up, i.e. the 3becomes 4.

6.4

Dr. A. Al-Saadi 44

If< 5, then the digit stays unchanged.

6.34becomes 6.3

8/2/2019 Chem 101-01

23/28

08-Sep-

2

Exercises

Perform the following mathematical operation and

express the result to the correct number of significant

Chapter 1 Section 5

figures:

011

273082101020

.

..

Dr. A. Al-Saadi 45

oun ng o s ou e carr e ou or e na answer

and NOT to the intermediate answers. However, you must

keep track of the significant figures in the intermediatesteps.

Precision and Accuracy

Chapter 1 Section 5

Dr. A. Al-Saadi 46

Random error Systematic error

Precise but notaccurate

reproducible

Neither precisenor accurate

Accurate andprecise

Poor technique Good technique butneeds calibration

Good technique

8/2/2019 Chem 101-01

24/28

08-Sep-

2


Accuracy: Agreement of a particular value

Chapter 1 Section 5

(measurement) with the true value.

Precision: Agreement among several

values (measurements), not necessarily

Dr. A. Al-Saadi 47

.


Chapter 1 Section 5

Three students are asked to determine themass o an as irin tablet.

Student A Student B Student C

0.335 g 0.357 g 0.369 g

0.331 g 0.375 g 0.373 g

0.333 g 0.338 g 0.371 g

Dr. A. Al-Saadi 48

Average:0.333 g 0.357 g 0.371 g

True mass was 0.370 grams

8/2/2019 Chem 101-01

25/28

08-Sep-

2


Chapter 1 Section 5

Three students are asked to determine themass o an as irin tablet.

Dr. A. Al-Saadi 49

True mass was 0.370 grams

Conversion Factors

Used to convert from one unit to another.

Chapter 1 Section 6

Example 1:How many centimeters arein 25.5 inches (in)?

in1

cm2.54in25.5 64.8 cm

Dr. A. Al-Saadi 50

Example 2:How many inches are in25.5 centimeters?

cm2.54

in1cm25.5 10.0 in

8/2/2019 Chem 101-01

26/28

08-Sep-

2

Dimensional Analysis Tracking Units

1L = 1000 ml

Chapter 1 Section 6

Example 3:

1 ml = 0.001 L

= 1 10-3 L

How many ml are in1.63 L?

Which direction you choose?

Dr. A. Al-Saadi 51

1.63 L =

1.63 L =

1000 ml?1 L

1000 ml

ml0.00163

1.63103 ml

How many centimeters are in 0.25 megameters?

Solving Problems Using DimensionalAnalysis

Chapter 1 Section 6

0.25 megameters = 0.25106 m

6 = 8

megameters1

m1106

cm100

Dr. A. Al-Saadi 52

. .

= 2.5107 cm

= 25.106 cm

1 meters

8/2/2019 Chem 101-01

27/28

08-Sep-

2

The Food and Drug Administration (FDA) recommendsthat dietar sodium intake be no more than 2400 m

Solving Problems Using Dimensional

Analysis

Chapter 1 Section 6

per day.

What is this mass in pounds (lb), if 1 lb = 453.6 g?

lb1g1 3

Dr. A. Al-Saadi 53

.g453.6mg1000

Exercise

Perform the following mathematical operation and

express the result to the correct number of significant

figures:

4326.0

705.80

623.0

470.0

1.3

526.2

Dr. A. Al-Saadi 54

oun ng o s ou e carr e ou or e na answer and NOT to the intermediate answers. However, you must

keep track of the significant figures in the intermediate

steps.

8/2/2019 Chem 101-01

28/28

08-Sep-

Exercise

Methodology to solve such problems:

Start with the quantity given in the question.

Use possible conversion factors to convert the unit of the

given quantity in the question to the desired/needed unit.

Dr. A. Al-Saadi 55

chem 101-01

Documents