CHEMISTRYPrecision and Design

CHAPTER 1Chemistry: An Introduction

Section 1.1: Chemistry: The Science of Matter Chemistry-the branch of science that

deals with the study of the composition, structure, and properties of matter and the changes that matter undergoes

Five major branches Physical Chemistry Organic Chemistry Inorganic Chemistry Biochemistry Analytical Chemistry

Branches of Chemistry

Physical Chemistry Deals with applying the theories of

physics to the study of reactions and properties of matter

Organic Chemistry Involves the study of substances that

are compounds of carbon Inorganic Chemistry

Involves the study of substances that are chemical combinations of elements other than carbon

Branches of Chemistry

Biochemistry The chemistry of living things Plants and animals

Analytical Chemistry Deals with identifying what substances are

present in materials and how much of each substance is present

There is overlap between these branches Many chemists are involved in areas that

combine two or more branches

Branches of Chemistry Clinical Chemistry

Involves biochemistry and analytical chemistry Concerned with analyzing biological materials

such as blood and urine Polymer Chemistry

Involves organic, physical, and analytical chemistry

Polymer chemists study polymers—a group of large molecules that includes nylon, rayon, polyesters, polyurethanes, and rubber

Pharmaceutical Chemistry Involves biochemistry, organic chemistry, and

analytical chemistry Deals with the manufacture, composition, and

effects of drugs

Applications of Chemistry

Chemistry is involved throughout our daily lives

Many careers employ principles of chemistry Farmers, medical doctors, beauticians,

truck drivers, dentists, nurses, etc. Many products are developed using

chemistry Cosmetics, hair sprays, toothpastes,

detergents, shampoos, deodorants, perfumes, medicines, etc.

Applications of Chemistry

In clothing and many other applications, petroleum-based synthetic fibers and plastics have replaced natural fibers such as silk and wool, and other substances such as rubber, leather, and metal

Cotton, wool, and silk are often treated chemically to wrinkle-proof, dye, or condition it

Applications of Chemistry

Variety and bounty of food Chemical pesticides and additives

Printing and production of books Computer chips Furniture Paint and wallpaper Carpet, tile A basic understanding of chemistry is

necessary for anyone entering the any of the scientific fields

Careers in Chemistry Chemist

Design and synthesize new compounds such as drugs or plastics

Analyze samples for their composition such as in quality control

Study the theories of matter and its behavior

Teach Chemical Engineers

Help design or oversee a chemical industrial plant

May be involved in selling equipment to companies

Careers in Chemistry Lab Technicians

Carry out routine analysis Operate instruments Prepare samples Help write reports

Scientific Journalism Report on scientific views for magazines

and newspapers Write technical publications

accompanying chemicals, instruments, or machinery

Write for professional journals

Careers in Chemistry Illustrator

For textbook publishers or scientific publications

Nutritionist Research nutritional problems Work with health-care teams in hospitals,

clinics, and government agencies Devise special diets for people with medical

problems Supervise preparation of food Develop new recipes Educate people about dietary requirements

Careers in Chemistry

Forensic Chemists Apply chemistry to legal questions Often involved in the area of criminology

(scientific crime detection) Analyze many kinds of substances taken

from the scene of a crime May testify in court to clearly explain the

significance of his chemical evidence Analyze and identify drugs

Careers in Chemistry

Agriculture—agronomist, forester, horticulturist

Engineering—nuclear, metallurgical, biomedical, environmental

Health science—medical doctor, nurse, dentist, veterinarian, pharmacist, physical therapist

The Nature of Science

Science—the systematic study of God’s universe and how it works

The scientific method Observing Hypothesizing Experimenting

The Scientific Method

Observing Gathering data (facts) about nature Involves measurement, organizing data,

and searching scientific literature to learn about the work of other scientists

The Scientific Method Hypothesizing

Suggesting explanations for observations Involves carefully considering all available data to

develop a hypothesis—a tentative explanation of a natural phenomenon

A good hypothesis must be testable There must be potential observations or experiments

that can disprove the hypothesis if it is false The hypothesis must also make reproducible

predictions Different scientists at different places and times to

verify the observations and experiments supporting it

Even a hypothesis that is testable and makes reproducible predictions is nothing more than an unproven idea

The Scientific Method Experimenting

Setting up carefully controlled artificial situations (experiments) to test a hypothesis

An ideal experiment involves changing one factor (the variable) while keeping all other factors (the constants) unchanged

If the effects of changing the variable do not match the effects predicted by the hypothesis, the hypothesis is probably flawed and must be revised or discarded

If the effects of changing the variable match the predictions of the hypothesis, the hypothesis may be true

The Scientific Method

In the real world, an incorrect hypothesis may make a correct prediction, or an experiment itself may be erroneous

Verifying a hypothesis requires repeating experiments and performing different types of experiments that test the same hypothesis

The Scientific Method

Once a hypothesis has been supported by many experiments and verified by other scientists, it is considered a theory

Although more sure than a hypothesis, a theory may still be proven false by observations and experiments

A theory that has stood the test of time may be considered a scientific law

Scientific laws represent man’s best understanding of how God’s universe works

The Purpose of Science

Science deals with only the physical universe

Science cannot answer all questions The science of chemistry is not

governed by haphazard or disordered principles but rather by an orderliness that leads to reproducible effects

Section 1.2:Measurement in Chemistry Mathematics—the “language of science” Precision—the consistency or reproducibility

of a measurement Random Errors reduce the precision that is

possible Random Errors fluctuate randomly about the true

value Example: two people read an instrument differently

giving each of them slightly different results

Accuracy—how close a measurement is to the actual, exact value Systematic errors affect accuracy Examples: defective instrument, a miscalibrated

instrument, or a poorly designed experiment

Accuracy Vs. Precision

Uncertainty

Exact Numbers—numbers that have no uncertainty Numbers obtained by counting Defined values

There are exactly 100 cm in 1 m

THERE IS ALWAYS SOME UNCERTAINTY IN A MEASUREMENT

The Metric System: Systems of Measurement System of measurement—a collection of

compatible, related units that can be used to measure various quantities

U.S.A. F.P.S.—foot-pound-second system A.K.A. English

system Metric System

The worldwide standard system of measurement for scientific and technical purposes

SI—a modification of the metric system with meticulously defined standards for all units

SI Prefixes

Prefix Symbol Meaning Multiplier

Numerical

nano n One billionth 10^-9 0.000000001

micro μ One millionth 10^-6 0.000001

milli m One thousandth

10^-3 0.001

centi c One hundredth

10^-2 0.01

deci d One tenth 10^-1 0.1

deca da Ten 10^1 10

hecto h One hundred 10^2 100

kilo k One thousand 10^3 1000

mega M One million 10^6 1,000,000

giga G One billion 10^9 1,000,000,000

tera T One trillion 10^12 1,000,000,000,000

Metric Units Used in ScienceQuantity Name Symbol

length meter m

mass kilogram kg

volume liter L

time second s

temperature degree Celsius

HC

absolute temperature

kelvin K

pressure pascal Pa

amount of substance

mole mol

energy joule J

electric current ampere A

voltage volt V

power watt W

force newton N

frequency hertz Hz

luminous intensity candela cd

Measuring Mass

Mass—the quantity of matter in an object Measured in kilograms

Weight—the force of gravity upon an object

Density

Represents the “compactness” of matter

ρ = m/V Density equals mass divided by volume

Temperature

Convert from Fahrenheit to Celsius C = 5/9 (F – 32)

Convert from Celsius to Fahrenheit F = 9/5(C) + 32

Absolute zero—the coldest possible temperature

Convert from Kelvin to Celsius C = K – 273.15

Converting Units

Dimensional Analysis Example 1.1: How many minutes are in

exactly 2 weeks?

Example 1.1 Answer

20,160 min

Section Review 1.2 Application 2. If the density of chloroform is 1.5

g/cm^3, what is the mass of 50.0 cm^3 of chloroform?

Answer:

75 g

Perform the Following Conversions 4.

A. 30.0 cm to meters B. 1.45 d (day) to seconds C. 0.00590 g to milligrams D. 5.0 cm/s to kilometers per hour

Answers

A. 0.300 m B. 125,280 s ≈ 125,000 s C. 5.90 mg D. 0.18 km/hr

Section 1.3: Mathematics in Chemistry