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GENERAL CHEMISTRY I

(CHM-101)

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CHAPTER ONE

Chemistry:The Study Of Change

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Chemistry:

Is the study of Matter and Its Changes

Matter is anything that has mass and also

volume.

Mass is the measure of the amount of matter in

an object.

Weight is the measure of the gravitationalforce for the matter in an object.

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Conversion Factors

Units of length1 m = 10 dm = 102 cm = 103mm = 109nm.

Units of time

1 s = 103 ms = 106s = 109 ns = 1012 ps = 1015 fs.

Units of weight

1g = 103mg = 106g = 109ng.

Units of volume

1L = 1dm3= 103cm3= 103mL; 1 mL = 1 cm3; 1 m3= 106cm3= 103dm3= 103L

where: L = Liter; mL = milliliter; d = deci; c = centi; m =

meter; g = gram; n = nano; = micro, f = femto, p = pico.

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SIGNIFICANT FIGURES

Are those digits in a measured number (or

result of the calculation with a measured

number) that include all certain digits plus a

final one having some uncertainty OR The

number of digits necessary to express the

results of a measurement consistent with the

measured precision.

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General Rules

Any number that is nonzero is significant.

Zeros between nonzero numbers aresignificant.

Zeros at the beginning of a number are never

significant.

Zeros at the right of the decimal and at the

same time to the right of the nonzero number

are significant.

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Examples: How many significant figures are

there in each of the following measurements?

0.0351 (3 sig. figs)

0.30210 (5 sig. figs)

52000 (2 sig. figs)

52.000 (5 sig. figs)

010850 (4 sig. figs)

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Scientific Notation

Ax 10n 1 A < 10

nis a positive or negative integer

Every dig i t inc luded in Ais s igni f icant

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Example: The integer number 100could have2 or 3 significant figures. It should be written in

one of the following ways:

1.00 x 102 (3 sig. figs) but NOT 10.0 x 101

1.0 x 102 (2 sig. figs) butNOT 0.10 x 103

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Rounding-off

If the first digit in the part of the number to be

dropped is 5 or greater than 5, increase theprevious digit by 1, then remove the excess

digits.

If the first digit in the part of the number to

be dropped is less than 5, simply remove theexcess digits.

Examples:

3.56343 3.56 (if rounded to 3 sig. figs)

3.56843 3.57 (if rounded to 3 sig. figs)

3.57500 3.58 (if rounded to 3 sig. figs)

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Significant Figures

in Multiplication Division

Example:0.41 x 2.546 x (3.12 x10

6

) =

7.0012

465183.5687 (calculator answer)

In multiplication and division, the answer shouldcontain same significant figures as the measurement

with the smaller number of significant figures.

The correct answer should have 2 sig. figs

(4.7 x 10

5

)

* Do not round off each step)

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Significant Figures

in Addition Substraction

Example:

937.3 + 15.224 + 71.04 = 1023.564 (calculator

answer)

In addition and subtraction, the final answer must havesame number of decimal places as the least precise

measurement that is, the measurement with the smallest

number of the decimal places.

The correct answer cannot have more than one

number to the right of the decimal point.

Therefore, the sum, 1023.564, should be rounded

to 1023.6

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The answer should read 0.0070(2 sig. figs).

Example: 8.9250 - 8.904 = 0.021 = 0.007 (calculator answer)

3 3

Exact

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Temperature Scales

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Celsius to Kelvin Conversion

Celsius to Fahrenheit Conversion

K = oC + 273

oF = (9/5)oC + 32

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CLASSIFICATION

OF MATTERS

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Liquid: molecules areclose together but not held

rigidly in a fixed position.

Gas: molecules are far away

from each other.

Solid: molecules are closetogether with little freedom

of motion.

States of Matter

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Solids: are rigid and have a definite

shape and volume.

Liquids: have definite volume but no

definite shape (take the shape of the container).

Gases: have no definite shape orvolume (takes the shape and volume of thecontainer). Gases can be compressed to form

liquids.

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Matter

Mixtures Puresubstances

Homogeneous

mixturesHeterogeneous

mixtures

Compounds Elements

Separation by

physical methods

Separation by

chemical methods

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Matter

Uniform throughout Not uniform throughout

Heterogeneous mixture

Homogeneous matter

cannot be separated byphysical means

can be separated by physical means

Pure substance

Homogeneous mixture

can be decomposed

into something else

by chemical means

Compound

cannot be decomposed

into something else by

chemical means

Element

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DENSITY

(g/mLorg/cm

3

)

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Density has many uses:

A tool for identification of substances.

To determine the amount of antifreeze & thus the level

of protection against freezing, in the cooling system of

a car.

The liquid in your carslead storage battery (a solutionof H2SO4) changes the density because H2SO4 is

consumed as the battery discharges.

In a fully charged battery, density (solution) = 1.30 g/cm3

If the density falls below 1.20 g/cm3, this means that the

battery will have to be charged.

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Good Luck

Dr. Imad A. Abu Yousef