chapter 1 chemistry the study of change(2)

8/18/2019 Chapter 1 Chemistry the Study of Change(2)

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Chemistry:

The Study of Change

Chapter 1

Copyright © The McGraw-Hill Companies, Inc !ermission re"uired for reproduction or display


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Sections# $utline%%: Chemistry: & Science for the '%st Century ()or

e*tra fun+%': The Study of Chemistry ($ptional reading+

% The Scientific Methods

% Classification of Matter %. The three states of matter

%/ !hysical !roperties of Matter

%0 Measurement

%1 Handling 2um3ers

%4 5imensional &nalysis

%%6 7eal-8orld !ro3lems (More fun+

2


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Chemistry: & Science for the '%st Century

9 Health and Medicine

9 Sanitation systems

9 Surgery with anesthesia

9 accines and anti3iotics

9 Gene therapy

9;nergy and the ;n


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Chemistry: & Science for the '%st Century

9 Materials and Technology

9 !olymers, ceramics, li"uid crystals

9 7oom-temperature superconductors=

9 Molecular computing=

9 )ood and &griculture

9 Genetically modified crops

9 >2atural? pesticides

9 Speciali@ed fertili@ers


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The Study of Chemistry

Macroscopic Microscopic


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The scientific method is a systematic

approach to research

& hypothesis is a tentati


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& theory is a unifying principle that e*plains

a 3ody of facts andAor those laws that are

3ased on them

& law is a concise statement of a relationship

3etween phenomena that is always the same

under the same conditions

&tomic Theory

)orce B mass * acceleration


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Chemistry In &ction:

In %46 George Gamow hypothesized that the uni


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Matter is anything that occupies space and

has mass

& substance is a form of matter that has a

definite composition and distinct properties

Chemistry is the study of matter and the

changes it undergoes

li"uid nitrogen gold ingots silicon crystals


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& mixture is a com3ination of two or more su3stances

in which the su3stances retain their distinct identities

% Homogenous mixture E composition of themi*ture is the same throughout

' Heterogeneous mixture E composition is not

uniform throughout

soft drin, mil, solder

cement,

iron filings in sand


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Physical means can 3e used to separate a mi*ture

into its pure components

magnet

distillation


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&n element is a su3stance that cannot 3e

separated into simpler su3stances 3y chemical

means.

9%% elements ha


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& compound is a su3stance composed of atoms

of two or more elements chemically united in fi*ed

proportions

Compounds can only 3e separated into their

pure components (elements+ 3y chemical

means

lithium fluoride "uart@ dry ice E car3on dio*ide


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Classifications of Matter


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& Comparison: The Three States of Matter


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The Three States of Matter: ;ffect of a Hot

!late on a Dloc of Ice

solidli"uid

gas


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& physical change does not alter the composition or

identity of a su3stance

& chemical change alters the composition or

identity of the su3stance(s+ in


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&n extensive property of a material depends upon

how much matter is 3eing considered

&n intensive property of a material does not

depend upon how much matter is 3eing

considered

9 mass

9 length

9


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Matter - anything that occupies space and has mass

mass E measure of the "uantity of matter

SI unit of mass is the kilogram (g+

% g B %666 g B % * %6 g

weight E force that gra


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International System of nits (SI+


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Volume E SI deri


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Density E SI deri


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E l 1 1


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Example 1.1

Gold is a precious metal that is chemically unreacti


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Example 1.1

olution 8e are gi


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Example 1.2

The density of mercury, the only metal that is a li"uid at roomtemperature, is %/ gAm Calculate the mass of ..6 m of

the li"uid

E l 1 2


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Example 1.2

olution 8e are gi


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J B 6C K '0%.

6) B * 6C K '4.

'0%. J B 6 6C

0%. J B %66 6C

' 6) B 6 6C

'%' 6) B %66 6C

& Comparison of Temperature Scales

Example 1 3


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Example 1.3

(a+ Solder is an alloy made of tin and lead that is used inelectronic circuits & certain solder has a melting point of

''LC 8hat is its melting point in degrees )ahrenheit=

(3+ Helium has the lowest 3oiling point of all the elements at'.'L) Con


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Example 1.3

olution These three parts re"uire that we carry out

temperature con


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Scientific 2otation

The num3er of atoms in %' g of car3on:

/6','66,666,666,666,666,666,666

/6'' * %6'

The mass of a single car3on atom in grams:

66666666666666666666666%44

%44 * %6-'

2 * %6n

2 is a num3er

3etween % and %6

n is a positi


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Scientific 2otation

./10/'

n > 0

./10/' B ./10/' * %62

mo


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Scientific 2otation

Multiplication

% Multiply 2% and 2'' &dd e*ponents n1 and n2

(6 * %6-.+ * (06 * %6+ B(6 * 06+ * (%6-.++ B

'1 * %6-' B

'1 * %6-%

5i


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ncertainty

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)(2 ±= tyUncertaini DivisionSmallest

Si ifi t )i


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Significant )igures

9 &ny digit that is not @ero is significant

%' g significant figures9 Oeros 3etween non@ero digits are significant

/6/ m significant figures

9 Oeros to the left of the first non@ero digit are not significant

661 % significant figure

9 If a num3er is greater than %, then all @eros to the right of thedecimal point are significant

'6 mg ' significant figures9 If a num3er is less than %, then only the @eros that are at theend and in the middle of the num3er are significant

666'6 g significant figures

Example 1 4


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Example 1.4

5etermine the num3er of significant figures in the following

measurements:

(a+01 cm

(3+/6% g

(c+61'. m

(d+66 g

(e+%%6 P %6'' atoms

(f+0666 m

Example 1 4


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Example 1.4

olution

(a+ 01 cm -- Three, 3ecause each digit is a non@ero digit

(3+ /6% g -- Three, 3ecause @eros 3etween non@ero digits are

significant

(c+ 61'. m -- Three, 3ecause @eros to the left of the firstnon@ero digit do not count as significant figures

(d+ 66 g -- Two Same reason as in (c+

(e+ %%6 P %6''

atoms -- )our, 3ecause the num3er is greaterthan one so all the @eros written to the right of the decimal point

count as significant figures

Example 1 4


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Example 1.4

(f+0666 m -- This is an am3iguous case The num3er of

significant figures may 3e four (0666 P %6,+, three (066 P

%6,+, two (06 P %6,+, or one (0 P %6,+

This e*ample illustrates why scientific notation must 3eused to show the proper num3er of significant figures

Si ifi t )i


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Significant )igures

&ddition or Su3traction

The answer cannot ha


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Significant )igures

Multiplication or 5i


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Significant )igures

;*act 2um3ers

2um3ers from definitions or num3ers of o3Fects are consideredto ha


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Example 1.5

Carry out the following arithmetic operations to the correct

num3er of significant figures:

9%%,'.% g K 6%41 g

9//.4 Q %%

91%/ m P .%..

(d+ 66%. g ÷ 11 m

(e+ '/ P %6, cm K '0 P %6' cm

Example


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Example

Rou ha


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Example 1.5

olution In addition and su3traction, the num3er of decimal

places in the answer is determined 3y the num3er ha


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Example 1.5

(c+

(d+

(e+ )irst we change '0 P %6' cm to 6'0 P %6, cm and thencarry out the addition ('/ cm K 6'0 cm+ P %6, )ollowing

the procedure in (a+, we find the answer is '40 P %6, cm

! h l t i t th t l


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!ccuracy E how close a measurement is to the true


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5imensional &nalysis Method of Sol


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Example

& person#s a


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Example 1.6

trategy The pro3lem can 3e stated as

= mg B 661 l3

The relationship 3etween pounds and grams is gi


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Example 1.6

olution The se"uence of con


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Example 6

Check &s an estimate, we note that % l3 is roughly .66 g and

that % g B %666 mg Therefore, % l3 is roughly . P %6. mg

7ounding off 661 l3 to 6% l3, we get . P %6- mg, which is

close to the preceding "uantity

Example 1.7


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Example

&n a


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Example

trategy

The pro3lem can 3e stated as

= m, B .'

How many con


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olution 8e need two con


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2ow we can write

Check )rom the preceding con


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i"uid nitrogen is o3tained

from li"uefied air and is used

to prepare fro@en goods and in

low-temperature research

The density of the li"uid at its3oiling point (Q%4/LC or 00 J+

is 6161 gAcm, Con


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trategy The pro3lem can 3e stated as

= gAm, B 6161 gAcm,

Two separate con


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olution In ;*ample %0 we saw that % cm, B % P%6Q/ m, Thecon

chapter 1 chemistry the study of change(2)

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