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CHEMISTRY 101
Dr. IsmailFasfous
 Textbook: Raymond Chang, 10th Edition
Office Location: Chemistry Building, Room 212
 Office Telephone: 4738
 Email: [email protected] & [email protected]
Website: http://staff.hu.edu.jo/ismailfasfous
1
Chemistry:
The Study of Change
Chapter 1
2
The Study of Chemistry
Macroscopic
We can see, touch and measure
Microscopic
We cannot without technology
1.2
Steps in the Scientific Method
1. Observations
 quantitative (water boils at 100 oC)
 qualitative (the sky is blue)
2. Formulating hypotheses
 a tentative explanation for the observation
3. Performing experiments
 gathering new information to decide
whether the hypothesis is valid
Copyright©2000 by Houghton
Mifflin Company. All rights reserved.
4
1.3
Extensive and Intensive Properties
An extensive property of a material depends upon
how much matter is is being considered.
• mass
• length
• volume
An intensive property of a material does not
depend upon how much matter is is being
considered.
• density
• temperature
• color
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 = 1.0
1 kg on earth
on moon, c ~ 0.1
0.1 kg on moon
1.7
Measurement
Measurement - quantitative observation consisting of
2 parts
Part 1 - number
Part 2 - scale (unit)
Examples:
20 grams
6.63   Joule seconds
Copyright©2000 by Houghton
Mifflin Company. All rights reserved.
7
1.7
The Fundamental SI Units
8
9
Measurement of
volume
1 L = 1000 mL = 1000 cm3 = 1 dm3
1 mL = 1 cm3
10
1.7
Common types of laboratory equipment
used to measure liquid volume.
11
1.7
Density is the mass of substance per unit volume of the
substance
– SI derived unit for density is kg/m3
1 g/cm3 = 1 g/mL = 1000 kg/m3
density =
mass
volume
m
d= V
1.7
A piece of iron metal with a density of 7.87 g/cm3 has a
volume of 5.94 cm3. What is its mass?0
m
d= V
m = d x V = 7.87 g/cm3 x 5.94 cm3 = 46.7 g
A cubic piece of a silver metal measures 4.25 cm on each
edge. If the density is 10.49 g/cm3, what is the mass of
the cube?
Mass = d.V. = (4.25cm)3 x 10.49 g/cm3 = 805 g
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K = 0C + 273.15
273 K = 0 0C
373 K = 100 0C
0F
= 9 x 0C + 32
5
32 0F = 0 0C
212 0F = 100 0C
1.7
Convert 172.9 0F to degrees Celsius.
9
=
x 0C + 32
5
0F – 32 = 9 x 0C
5
0F
5 x (0F – 32) = 0C
9
0C = 5 x (0F – 32)
9
0C = 5 x (172.9 – 32) = 78.3
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1.7
Uncertainty in Measurement
A digit that must be estimated is called
uncertain. A measurement always has
some degree of uncertainty.
16
20.16ml
20.17ml
20.15ml
20.18ml
±0.01ml
Figure : Measurement of volume using a buret. The volume is read at
the bottom of the liquid curve (called the meniscus).
17
Precision and Accuracy
Accuracy refers to the agreement of a
particular value with the true value.
Precision refers to the degree of agreement
among several elements of the same
quantity.
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Precision and Accuracy
accurate
&
precise
precise
but
not accurate
not accurate
&
not precise
Rules for Counting Significant Figures Overview
1. Nonzero integers (1-9)
2. Zeros
 leading zeros, before (1-9)
 captive zeros, between (1-9)
 trailing zeros, after (1-9)
3. Exact numbers
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Rules for Counting Significant
Figures - Details
Nonzero integers always count as
significant figures.
3456 has
4 sig figs.
21
Rules for Counting Significant
Figures - Details
Zeros

Leading zeros do not count as
significant figures.
0.0486 has
3 sig figs.
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Rules for Counting Significant
Figures - Details
Zeros

Captive zeros always count as
significant figures.
16.07 has
4 sig figs.
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Rules for Counting Significant
Figures - Details
Zeros
 Trailing zeros are significant only
if the number contains a decimal point.
9.300 has
4 sig figs.
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Rules for Counting Significant
Figures - Details
Exact numbers have an infinite number of significant
figures.
Independent of measuring device:
1 apple, 10 students, 5 cars….
2πr The 2 is exact and 4/3 π r2 the 4 and 3 are exact
From Definition: 1 inch = 2.54 cm exactly
The 1 and 2.54 do not limit the significant figures
Average of certain values
7.64 + 7.68 + 7.70
= 7.67333 = 7.67 = 8
3
Because 3 is an exact number
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Scientific Notation
The number of atoms in 12 g of carbon:
602,200,000,000,000,000,000,000
6.022 x 1023
The mass of a single carbon atom in grams:
0.0000000000000000000000199
1.99 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
568.762
move decimal left
n>0
568.762 = 5.68762 x 102
0.00000772
move decimal right
n<0
0.00000772 = 7.72 x 10-6
Addition or Subtraction
1. Write each quantity with
the same exponent n
2. Combine N1 and N2
3. The exponent, n,
remains the same
4.31 x 104 + 3.9 x 103 =
4.31 x 104 + 0.39 x 104 =
4.70 x 104
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Scientific Notation
100. has 3 sig. fig. = 1.00 x 102
100 has 1 sig. fig. = 1 x 102
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Rules For Rounding
1. In a series of calculations, carry the extra digits
through to the final result, then round.
2. If the digit to be removed:
A. Is less than 5, then no change e.g. 1.33
rounded to 2 sig. fig = 1.3
B. Is equal or greater than 5, the preceding digit
increase by 1 e.g. 1.36 rounded to 2 sig. fig =
1.4
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Rules for Significant Figures in
Mathematical Operations
Multiplication and Division: # Sig figs in
the result equals the number in the least
precise measurement used in the calculation.
6.38  2.0 =
12.76  13 (2 sig figs)
30
Rules for Significant Figures in
Mathematical Operations
Multiplication and Division:
4.51 x 3.6666 = 16.536366= 16.5
3 sig figs
round to
3 sig figs
6.8 ÷ 112.04 = 0.0606926= 0.061
2 sig figs
round to
2 sig figs
31
Rules for Significant Figures in
Mathematical Operations
Addition and Subtraction: # decimal places in the
result equals the number of decimal places in the
least precise measurement.
6.8 + 11.934 =
18.734  18.7 (3 sig figs)
32
Rules for Significant Figures in
Mathematical Operations
Addition and Subtraction:
89.332
+1.1
90.432
3.70
-2.9133
0.7867
one significant figure after decimal point
round off to 90.4
two significant figures after decimal point
round off to 0.79
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Practice
Determine the number of significant figures in each of
the following measured quantities?
a)0.000387 m (3)
b) 2.90x108 g (3)
c) 905.040 cm (6)
d) 6.065 L (4)
34
Practice
Round off the following to three significant figures:
a)264.89 m = 265 m
b) 30 g = 30.0 g
c) 3275 ml = 3.28 x 103 ml
d) 2.2x10-5 mm = 2.20 x10-5 mm
35
Practice
Perform the following calculations and round off the answer to
the proper significant figures:
1. 1.25 m + 6.2 m – 8.01 m + 0.899 m = 0.3m
2.
78.8680 g/ (23.5ml + 10 ml) = 2.4g/ml
3. 50.0g x (11.9ml - 7 ml) = 245g/ml=200g/ml
4. 50.0g x (12.1ml-7ml)=255g/ml=300g/ml
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Dimensional Analysis Method of Solving Problems
Proper use of “unit factors” leads to proper units in
your answer:
2.54 cm = 1 inch
1 inch/2.54 cm = 1 Unit factor
What is the length in inch of 2.85 cm pencil
2.85 (cm) x 1 (inch)/2.54(cm) = 2.85/2.54 = 1.12 in
37
Dimensional Analysis Method of Solving Problems
1. Determine which unit conversion factor(s) are needed
2. Carry units through calculation
3. If all units cancel except for the desired unit(s), then the
problem was solved correctly.
How many mL are in 1.63 L?
1 L = 1000 mL
1000 mL
1.63 L x
= 1630 mL
1L
2
1L
L
1.63 L x
= 0.001630
1000 mL
mL
38
Practice
Perform the following conversions:
a)0.0033 mm to nm
(0.0033mm)(1m/1000mm)(109 nm/1m) = 3300nm
b) 0.67 pm to cm
(0.67pm)(1m/ 1012 pm)(100cm/1m) = 6.7 x10-11 cm
c) 4.60x10-6 kg/L to mg/ ml
(4.60x10-6kg/L)(1000g/1kg)(1000mg/1g)(1L/1000ml)
= 4.60 x 10-3 mg/ml
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Practice
The speed of sound in water is about 1482 m/s. What is this
speed in miles per hour?
conversion units
meters to miles
seconds to hours
1 mi = 1609 m
1 min = 60 s
1 hour = 60 min
1 mi
60 s
60 min
m
mi
x
x
1482 s x
= 3316
hour
1609 m 1 min
1 hour
1.9
Practice
Convert the density 0.808 g/cm3 to units of kg/m3?
conversion units
1 kg = 1000g
1 cm3 = 1 x 10-6 m3
g
1 kg
1 cm3
kg
x
0.808 cm3x
= 808 3
-6
3
m
1000 g 1x10 m