Notesale: Turn your study into money

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Introduction
Chapter 1

Copyright © The McGraw-Hill Companies, Inc
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Chemistry is the study of matter and the
changes it undergoes
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A substance is a form of matter that has a
definite composition and distinct properties
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Force = mass x acceleration

A theory is a unifying principle that explains
a body of facts and/or those laws that are
based on them
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1
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Heterogeneous mixture – composition is not
uniform throughout
cement,
iron filings in sand
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Physical means can be used to separate a mixture
into its pure components
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•114 elements have been identified
• 82 elements occur naturally on Earth
gold, aluminum, lead, oxygen, carbon, sulfur

• 32 elements have been created by scientists
technetium, americium, seaborgium
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Replace with Table 1
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Compounds can only be separated into their
pure components (elements) by chemical
means
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5 from 7e page 7

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A Comparison: The Three States of Matter

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11

Types of Changes
A physical change does not alter the composition
or identity of a substance
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hydrogen burns in
air to form water
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Extensive and Intensive Properties
An extensive property of a material depends upon
how much matter is being considered
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• density
• temperature

• color

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Matter - anything that occupies space and has mass
mass – measure of the quantity of matter

SI unit of mass is the kilogram (kg)
1 kg = 1000 g = 1 x 103 g

weight – force that gravity exerts on an object
weight = c x mass

A 1 kg bar will weigh

on earth, c = 1
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1

0
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2 on page 9

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Replace table with Table 1
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1
Gold is a precious metal that is chemically unreactive
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A piece of gold ingot with a mass of 301 g has a volume of
15
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Calculate the density of gold
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1
Solution We are given the mass and volume and asked to
calculate the density
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1), we write

A Comparison of Temperature Scales

K = 0C + 273
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15 K = 0 0C
373
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2

(a) Solder is an alloy made of tin and lead that is used in
electronic circuits
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What is its melting point in degrees Fahrenheit?
(b) Helium has the lowest boiling point of all the elements at
2452°F
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(c) Mercury, the only metal that exists as a liquid at room
temperature, melts at 238
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Convert its melting point to
kelvins
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2
Solution These three parts require that we carry out
temperature conversions, so we need Equations (1
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3),
and (1
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Keep in mind that the lowest temperature on the
Kelvin scale is zero (0 K); therefore, it can never be negative
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022 x 1023
The mass of a single carbon atom in grams:
0
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99 x 10-23

N x 10n
N is a number
between 1 and 10

n is a positive or
negative integer
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Scientific Notation
568
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00000772

move decimal left

move decimal right

n>0

n<0

568
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68762 x 102

0
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72 x 10-6

Addition or Subtraction
1
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Combine N1 and N2
3
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31 x 104 + 3
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31 x 104 + 0
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70 x 104

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Scientific Notation
Multiplication
1
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Add exponents n1 and n2

Division
1
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Subtract exponents n1 and n2

(4
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0 x 103) =
(4
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0) x (10-5+3) =
28 x 10-2 =
2
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5 x 104 ÷ 5
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5 ÷ 5
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7 x 10-5

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Significant Figures
• Any digit that is not zero is significant
1
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08 L

1 significant figure

• If a number is greater than 1, then all zeros to the right of the
decimal point are significant
2
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00420 g

3 significant figures
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Example 1
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03 g
(c) 0
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052 kg
(e) 2
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3
Solution

(a) 394 cm -- Three, because each digit is a nonzero digit
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03 g -- Three, because zeros between nonzero digits are
significant
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714 m -- Three, because zeros to the left of the first
nonzero digit do not count as significant figures
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052 kg -- Two
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(e) 2
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Example 1
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The number
of significant figures may be four (3
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00 × 103), two (3
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This example illustrates why scientific notation must be
used to show the proper number of significant figures
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89
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1
90
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70
-2
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7867

one significant figure after decimal point
round off to 90
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79

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Significant Figures
Multiplication or Division
The number of significant figures in the result is set by the original
number that has the smallest number of significant figures
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51 x 3
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536366 = 16
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8 ÷ 112
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0606926 = 0
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The average of three measured lengths: 6
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68 and 6
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64 + 6
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70
= 6
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67 = 7
3
Because 3 is an exact number
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Example 1
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1 g + 0
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59 L − 3
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16 m × 5
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0154 kg  88
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64 × 103 cm + 3
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4
Solution In addition and subtraction, the number of decimal
places in the answer is determined by the number having the
lowest number of decimal places
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(a)

(b)

Example 1
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27 × 102 cm to 0
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64 cm + 0
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Following
the procedure in (a), we find the answer is 2
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Dimensional Analysis Method of Solving Problems
1
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Carry units through calculation
3
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given quantity x conversion factor = desired quantity

given unit x

desired unit
given unit

= desired unit

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Example 1
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0833 pound (lb)
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6 g
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5
Strategy The problem can be stated as
? mg = 0
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This relationship will enable conversion from pounds
to grams
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Arrange the appropriate conversion factors so that pounds and
grams cancel and the unit milligrams is obtained in your
answer
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5
Solution The sequence of conversions is

Using the following conversion factors

we obtain the answer in one step:

Example 1
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Therefore, 1 lb is roughly 5 × 105 mg
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0833 lb to 0
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Example 1
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What is
the volume in m3?

A cryogenic storage tank
for liquid helium
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6
Strategy The problem can be stated as
? m3 = 275 L

How many conversion factors are needed for this problem?
Recall that 1 L = 1000 cm3 and 1 cm = 1 × 10−2 m
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6
Solution We need two conversion factors here: one to convert
liters to cm3 and one to convert centimeters to meters:

1000 cm3
1L

and

1 × 10-2 m
1 cm

Because the second conversion deals with length (cm and m)
and we want volume here, it must therefore be cubed to give
3

1 × 10-2 m
1 × 10-2 m
1 × 10-2 m
×
×
=
1 cm
1 cm
1 cm

1 × 10-2 m
1 cm

This means that 1 cm3 = 1 × 10-6 m3
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275 m3

Example 1
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Therefore, a 275-L storage tank would be
equal to 275 × 10-3 m3 or 0
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Example 1
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The density of the liquid at its
boiling point (−196°C or 77 K)
is 0
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Convert the
density to units of kg/m3
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7
Strategy The problem can be stated as
? kg/m3 = 0
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Example 1
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7 we saw that 1 cm3 = 1 ×10−6 m3
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Therefore, the answer is
reasonable

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