I. Matter and Meas

8/2/2019 I. Matter and Meas

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Assoc.Prof. Dr. Sermin Tetik

International CyprusUniversityFaculty of Pharmacy

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Preface

The chemistry is essential to a trueunderstanding of fields that range from cell

biology to medicine.

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Today, most people in the industrializednations have a higher standart of living than

the human race has ever known; morenutritious food, better health, greater wealth.

Much of this property is due to chemistry

Chemistry: Matter and Measurement


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Chemistry enables us to design all sorts of

materials;

drugs to fight disease, pesticides to protect our health and crops;

fertilizers to grow abundant food;

fuel for transportation; building materials for affordable housing;

plastics to package food;

sport equipment to enrich our leisure time;and much more..



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Chemistry plays a vital role in ourunderstanding and treatment of diseases

such as cancer and AIDS. In fact, the theories of chemistry illuminate

our understanding of the material world fromthiny atoms to giand galaxies.

Chemistry is a study of the composition,structure, and properties of matter and ofchanges that occur in matter.



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What is matter?

It is the stuff things are made of.

Wood, sand, people, water and air are allexamples of matter.

Heat and light are not matter; they are forms

of energy.



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Composition refers to type of atoms and theirrelative proportions in a sample of matter.

For example; at the microscopic level wemight describe a molecule of water asconsisting of one oxygen atom and twohydrogen atoms.



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A Physical property is a characteristicdisplayed by a sample of matter as it

undergoes a change in composition. When ethyl alcohol is identified by its odor,

there is no change in its composition. Anotherway to distinguish between ethyl alcohol and

water is that ethyl alcohol burns and waterdoes not.

But when ethyl alcohol burns, it is converted

to carbon dioxide gas and water.

Properties


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When ice melts, solid water is changed toliquid water. The water undergoes rather

profound change at the macroscopic level-what we see-but not at the microscopic level.

Water molecules have two hydrogen atomsfor every oxygen atom in both solid and liquid

water.

Properties


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In a physical change, a sample of matter,usually undergoes some noticable change at

the macroscopic level, but no change at themicroscopic level-no change in composition.

Properties


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Properties

A chemical property is a characteristic displayedby a sample of matter as it undergoes a change

in composition. Consider the composition of the carbon dioxide

molecules and water, which result from burningethyl alcohol.


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Properties

..Carbon dioxide molecules have

two oxygen atoms to one carbon atom and

..Ethyl alcohol molecules havesix hydrogen atoms to two carbon atoms to one

oxygen atom.

Thus, we conclude that flammability, and ability

to burn, is a chemical property.


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Properties

By contrast, in a chemical change, also called achemical reaction, a sample of matter undergoes

a change in composition and/or the structure ofits molecules.

The cooking of foods are common examples ofchemical changes.


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A type of matter that has a definite, or fixed,composition that does not vary from one sample

to another is called a substance. All substanceare either elements or compounds.

An element is a substance that cannot bebroken down into other simpler substances by

chemical reactions. Viewed at the microscopiclevel, an element is made up of atoms of only asingle type. At the present, 112 elements areknown.

Classifying Matter


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Classifying Matter

A compound is a substance made up of atoms oftwo or more elements, with the different kinds

of atoms combined in fixed proportions. In the compound water, the fundamental units

are molecules having two hydrogen atomsjoined to an oxygen atom.

Compounds can be broken down into simplersubstances elements- by chemical reactions. The possible number of compounds is essentialy

limitless.


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Compounds are designated by combinations ofchemical symbols called chemical formulas.

Most symbols are based on English names; afew are based on the atom name of the elementor one of its compounds.

The first letter of a symbol is capitalized and the

second letter is always lower case. For example,Co is the symbol for the element cobalt;

CO represents the poisonous compound carbonmonoxide.

Classifying Matter


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Classifying Matter

In the sheme for classifying matter we see twobroad categories of matter;

Substance and mixtures.

A mixure has no fixed composition, itscomposition may vary over a broad range.Ordinary table salt and water form a mixure,and we can vary the proportions of salt andwater from sample to sample.


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A mixure that has the same composition and

properties throughout is called a homogenousmixture, or a solution.

A given solution at salt in water, sometimescalled a saline solution.

In contrast, a heterogenous mixture varies incomposition or/and properties from one part ofthe mixure to another.

Classifying Matter


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Classifying Matter

Both homogenous and heterogenous mixturescan be seperated into their individualcomponents by physical changes-chemical

reactions are not required. The dissolved salt can be obtained from a saline

solution by allowing the water to evaporateaway.

Sand can be recovered from a sand-watermixure by passing the mixure through filterpaper similar to that used in coffee makers. Thewater passes through paper, and the sand is

held back.


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Chemist or other scientist use certain terms to

describe the way in which they conduct theirstudies. I will briefly consider some of theseterms.

Scientific Methods


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Scientific Methods

A hypothesis is a tentative explanation or

prediction concerning some phenomenon. Scientists test a hypotesis through a carrefully

controlled procedure called an experiment.

The facts obtained through careful observation

and measurements made during experimentscalled scientific data.


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Scientific Methods

Examples of scientific data are the melting point

of iron (1535oC) and the speed of light(2.99792458X108 meters per second).

Further experiments may refine these data tosome degree but the basic facts can be verified

by other scientist in similar experiments; thedata are reproducible.


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Scientists try to identify patterns in large

collections of data and to summarize thepatterns in the brief statements called scientificlaws. May of these laws can be statedmathematically.

Scientific Methods


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The ultimate goal of scientists is to formulate

theories. A scientific theory provides explanations of

observed natural phenomena and predictionsthan can be tested by further experiments.

Scientific Methods


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Scientific Measurements

It is the much easier to gather and check data,that are so essential to the methods of science.

The system agreed upon in 1960 is theInternational System of Units (SI), a modernizedversion of the metric system established inFrance in 1791.


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It has 4 unit system,

MKS (meter, kilogram, second)

CGS (centimeter, gram, second) MTS (meter, tone, second)

MKSA (SI) (meter, kilogram, second, amper)


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Physical Quantity Name of Unit Symbol of Unit

Lenght meter m

Mass Kilogram kgTime Second s

Temperature Kelvin K

Amount of substance Mole mol

Electric current Ampere A

Luminous intensity Candela cd


The Seven SI Base Units


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Multiple Prefix Symbol of Unit

101 deca da

102 hecto h103 kilo K

106 mega M

109 giga G

1012 tera T


Some Commen SI Prefix


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Some Commen SI Prefix

Multiple Prefix Symbol of Unit

10-1 deci d

10-2 centi c10-3 milli m

10-6 micro

10-9 nano n

10-12 pico p


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Mass

Mass is the quantity of matter in an object. Masscan be measured in many ways, but the mostcommon is through weighing.

The weight of an object is the force ofEarths

gravity on the object, and this force is directlyproportional to the mass of the object.



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Mass

The SI base quantity of mass is the kilogram

(kg). A more convenient mass unit for most laboratory

work is the gram.

1 kg=103 g=106mg

The milligram (mg) is a suitable unit for smallquantities of materials, such as some drugdosages

1 mg=10-3 microg


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Temperature

The SI base unit is the kelvin (K).

For the routin laboratory work, we often useCelsius temperature scale.On this scale thefreezing point of water is 0 degrees Celcius (oC)an the boiling point is 100 degree Celcius.

The interval between these two reference pointsis divided into 100 equal parts, each a degreeCelcius.


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Temperature

Another temperature scale widely used in theUnited States is the Fahrenheit scale.

Their treatment of an important physicalproperty-the freezing point of water.

0oC=32 oF

The temperature interval called a degree. A 10-degree temperature intervalon the Celsius scaleequals an 18-degree interval on the fahrenheitscale.



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Temperature

These two facts are the basis of two equationsthat relate temperatures on the two scales.

One of these requires multiplying the degreescelsius temperature by the factor 1.8 (that is18/10)to obtain degrees of Fahrenheit degrees.

T(K)= t (oC) + 273

t(oF)= 1.8 x t (oC) + 32

K = 0oC + 273

oF = oC x 1.8 + 32


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Density Density (d) is the mass per unit volume of a

substance. This important physical property isdefinet by the following equations:

md=______

V

The SI unit of density is k,lograms per cubic meter(kg/m3 or kgm-3), but densities are more oftenmeasured in grams per cubic centimeter,

(g/cm3) or grams per mililiter (g/mL)



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Volume

The SI unit of volume is the cubic meter (m3)

1 mL = 1 cm3

1 L = 1 dm3 = 1000 cm3


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Lenght

The SI base unit of lenght is the meter (m). 1 m= 10 2 cm = 10 3 mm = 10 6 microm

1 micro m = 10 -6 m

1 nm = 10 -9 m



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Pressure

The SI base unit of pressure is the atmosphere.

1 A = 760 mm Hg= 76 cm Hg Energy

The SI base unit ofenergy is the joule (kgm2 /s2)

1 joule = 0.239 cal 1 Cal = 4.184 j

1 erg = 10 -7j

1 joule = 10 7 erg


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Sampling Errors

Measurements would yield varying results depending onseveral factors.

Counting can be exact: We can count exactly students

in a room. Measurements, on the other hand, aresubject to error.

One source of error is the measuring instrumentthemselves.

Other errors may result from the experimenters lack ofskill or care in using measuring instruments.

The accuracy of a set of measurement refers to thecloseness of the average of the set to the correctormost probable value.


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We say the certain or uncertain about thenumerical.

25 (uncertainty +/- 1)

2300 (uncertainty +/- 100)

0.029 (uncertainty +/- 0.001)

26.64 (uncertainty +/- 0.01)

Significant Figures


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When we read a number from left to right , allthe digits starting with the first nonzero digit aresignificant.

0.006004800

significant figures are 7

Significant Figures


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Significant Figures in Calculations

Numbers uncertainty significant figures683 +/-1 3

6830 +/-10 4

6830.510 +/-0.001 7

0.00045 +/-0.00001 2

0.0403 +/-0.0001 3

8.000 +/-0.001 4

7.210 +/-0.001 415.00 +/-0.01 4

10.00005 +/-0.00001 7

0.0015 +/-0.0001 2


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Sampling Errors

In multiplication and divison, the reported result shouldhave no more significant figures than the factor with thefewest significant figures.

In rounding, we drop all digits that are not significant.These are the rules that we eill follow in rounding.

If the leftmost digit to be dropped is 0, 1, 2, 3, 4, leavethe final remaining digit unchanged.

Example: 369,443 rounds to 369, 44 if we need fivesignificant figures, and to 369,4 if we need four.

fthe leftmost digit to be dropped is 5,6,7,8,9 increasethe final digit by one.

I. Matter and Meas

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