Transcript HonorsCh2Chartsv2011

Honors Chemistry, Chapter 2
Page 1
 Evolution
of a Gas (Bubbles, Odor)
 Formation of a Precipitate (Formation of
Cloudiness in a Clear Solution, Solids
Collecting at the Bottom or Top)
 Release of Energy (Heat, Light)
 Color Change
Honors Chemistry, Chapter 2
Page 2
 Observing and Collecting Data
• Qualitative (Bubbles Formed)
• Quantitative (1 gram/liter of catalyst speeded
the reaction by 25%)
• Chemists Study Systems (Region Selected for
Study)
 Formulate Hypothesis
• Generalization about Data
• Testable Statement
Honors Chemistry, Chapter 2
Page 3
 Testing
Hypothesis (Experimentation)
• Supported, Retained
• Not Supported, Discarded, Modified
 Theorizing
– Create a Model
• Model: An Explanation of How Phenomena
Occur and How Data or Events are Related.
 Visual
 Verbal
 Mathematical
Honors Chemistry, Chapter 2
Page 4
JFHICW FH VHHVLBFND FL N
ZGVHFIVLB, BTV NZZVNGNLPV CY
JFHICW JFDD IC FL N PNLIFINBV. –
VGFP HVRNGVFI.
Honors Chemistry, Chapter 2
Page 5
JFHICW FH VHHVLBFND FL N ZGVHFIVLB,
BTV NZZVNGNLPV CY JFHICW JFDD IC
FL N PNLIFINBV. – VGFP HVRNGVFI.
(Wisdom is essential in a
president, the appearance of
wisdom will do in a candidate. –
Eric Severeid)
Honors Chemistry, Chapter 2
Page 6
1.
2.
3.
What is the purpose of the scientific
method?
Distinguish between qualitative and
quantitative observations.
Describe the differences between
hypothesis, theories, and models.
Honors Chemistry, Chapter 2
Page 7
 Measurements
Are Quantitative
Information
 Quantity: Something That Has Size or
Amount
Honors Chemistry, Chapter 2
Page 8
 SI
Units Are Defined in Terms of
Standards of Measurement
 Seven Basic Units
 All Others Derived From Seven Basic
Units
Honors Chemistry, Chapter 2
Page 9
Quantity
Symbol
Unit
Abbreviation
Length
Mass
Time
l
m
t
meter
Kilogram
second
m
Kg
s
Thermodynamic
Temperature
T
Kelvin
K
n
I
mole
ampere
mol
A
Iv
candela
cd
Amount of a
Substance
Electric Current
Luminous
Intensity
Honors Chemistry, Chapter 2
Page 10
Prefix
Abbreviation
Exponent
Multiplier
tera-
T
1012
1000000000000
1 terameter (Tm)
giga-
G
109
1000000000
1 gigameter (Gm)
mega-
M
106
1000000
1 megameter (Mm)
kilo-
k
103
1000
1 kilometer (km) = 1000 m
hecto-
h
102
100
1 hectometer (hm) = 100 m
deka-
da
101
10
1 dekameter (dam) = 10 m
100
1
1 meter (m)
Honors Chemistry, Chapter 2
Page 11
Meaning
Example Using Length
Prefix
Abbreviation
Exponent
Multiplier
Meaning
Example Using Length
100
1
1 meter (m)
deci-
d
10-1
0.1
1 decimeter (dm)
centi-
c
10-2
0.01
1 centimeter (cm)
milli-
m
10-3
0.001
1 millimeter (km)
micro-

10-6
0.000001
1 micrometer (m)
nano-
n
10-9
0.00000001
1 nanometer (nm)
pico-
p
10-12
0.000000000001
1 picometer (pm)
Honors Chemistry, Chapter 2
Page 12
Useful Conversion Factors
•
•
•
•
•
•
•
1000 ml
1 cm3
1000 g
1000 mg
1000 g
1000000 g
1000 mmol
Honors Chemistry, Chapter 2
Page 13
=
=
=
=
=
=
=
1L
1 ml
1 kg
1g
1 mg
1g
1 mol
1. 1000 m = 1 ___
a) mm b) km c) dm
2. 0.001 g = 1 ___
a) mg
b) kg c) dg
3. 0.1 L = 1
a) mL
b) cL c) dL
___
4. 0.01 m = 1 ___
a) mm b) cm c) dm

? kilometer (km) = 500 meters (m)

2.5 meter (m) = ? centimeters (cm)

1 centimeter (cm) = ? millimeter (mm)

1 nanometer (nm) = 1.0 x 10-9 meter
O—H distance =
9.4 x 10-11 m
9.4 x 10-9 cm
0.094 nm
Select the unit you would use to measure
1. Your height
a) millimeters b) meters c) kilometers
2. Your mass
a) milligrams
b) grams
c) kilograms
3. The distance between two cities
a) millimeters b) meters c) kilometers
4. The width of an artery
a) millimeters b) meters c) kilometers
 Area
 Volume
 Density
 Molar
Mass
 Concentration
 Molar Volume
 Energy
Honors Chemistry, Chapter 2
Page 18
A
V
D
M
c
Vm
E
m2
m3
kg/m3 (=m/V)
kilograms/mol
mol/liter
m3/mol
joule
 Relationship
Between D, m, and V:
m
D
Honors Chemistry, Chapter 2
Page 19
V
First, note that 1
cm3 = 1 mL
Strategy
1.Use density to calc. mass (g) from
2.Convert mass (g) to mass (lb)
Need to know conversion factor
= 454 g / 1 lb
volume.
1.
Convert volume to mass
13.6 g
3
3
95 cm •
= 1.3 x 10 g
3
cm
2.
Convert mass (g) to mass (lb)
3
1.3 x 10 g •
1 lb
= 2.8 lb
454 g
Osmium is a very dense metal. What is its
density in g/cm3 if 50.00 g of the metal occupies
a volume of 2.22cm3?
1) 2.25 g/cm3
2) 22.5 g/cm3
3) 111 g/cm3
2) Placing the mass and volume of the osmium
metal into the density setup, we obtain
D = mass = 50.00 g =
volume
2.22 cm3
= 22.522522 g/cm3 = 22.5 g/cm3
A solid displaces a matching volume of water
when the solid is placed in water.
33 mL
25 mL
What is the density (g/cm3) of 48 g of a metal if
the metal raises the level of water in a graduated
cylinder from 25 mL to 33 mL?
1) 0.2 g/ cm3
2) 6 g/m3
3) 252 g/cm3
33 mL
25 mL
Which diagram represents the liquid
layers in the cylinder?
(K) Karo syrup (1.4 g/mL), (V)
vegetable oil (0.91 g/mL,) (W) water
(1.0 g/mL)
1)
2)
3)
K
V
W
K
W
K
V
V
W
The density of octane, a component of
gasoline, is 0.702 g/mL. What is the mass, in
kg, of 875 mL of octane?
1) 0.614 kg
2) 614 kg
3) 1.25 kg
If blood has a density of 1.05 g/mL, how
many liters of blood are donated if 575 g
of blood are given?
1) 0.548 L
2) 1.25 L
3) 1.83 L
Fractions in which the numerator and
denominator are EQUAL quantities expressed
in different units
Example:
1 in. = 2.54 cm
Factors: 1 in.
and 2.54 cm
2.54 cm
1 in.
Write conversion factors that relate each
of the following pairs of units:
1. Liters and mL
2. Hours and minutes
3. Meters and kilometers
Conversion factor
2.5 hr x
60 min
1 hr
= 150 min
cancel
By using dimensional analysis / factor-label method, the
UNITS ensure that you have the conversion right side up,
and the UNITS are calculated as well as the numbers!




Express 4.5 kg as grams
Begin by Expressing as a Fraction: 4.5 kg
1
Identify Conversion Factor: 1 kg = 1000 grams
Express as a Fraction:
1 kg
1 = --------------1000 g
Honors Chemistry, Chapter 2
Page 33
or
1000 g
-------------1 kg
 Write
Equation Including Proper Factor
 Cancel Units
 Multiply Numbers to Get Final Result
4.5 kg
--------- x
1
Honors Chemistry, Chapter 2
Page 34
1000 g
-------------- = 4500 g
1 kg
Factor Label Steps
1. Express as a Fraction
2. Identify Conversion Factor
3. Express Conversion Factor as Two
Fractions
4. Select Proper Factor (units in denom.)
5. Write Equation Including Proper Factor
6. Cancel Units
7. Multiply Numbers to Get Final Result
Honors Chemistry, Chapter 2
Page 35
1.
2.
3.
4.
5.
Distinguish between a quantity, a unit,
and a measurement standard.
Name SI units for length, mass, time,
volume, and density.
Distinguish between mass and weight.
Perform a density calculation.
Transform a statement of equality to a
conversion factor (factor label method).
Honors Chemistry, Chapter 2
Page 36
 Accuracy
– The Closeness of
Measurements to the Correct or
Accepted Value
 Precision – The Closeness of a Set of
Measurements
Honors Chemistry, Chapter 2
Page 37
XX
XX
XX
XX
High Precision
High Accuracy
Honors Chemistry, Chapter 2
Page 38
High Precision
Low Accuracy
Accuracy vs. Precision
X
X
X
X
X
X
X
X
Low Precision
Low Accuracy
Honors Chemistry, Chapter 2
Page 39
Low Precision
High Accuracy
(on average)
Valueaccepted - Valueexperimental
%Error = --------------------------------------Valueaccepted
X 100
Honors Chemistry, Chapter 2
Page 40
 All
the Digits Known With Certainty Plus
One Final Digit Which is Somewhat
Uncertain
| I I I I | I I I I | I I I I | I I I I |
7
8
8.36
Honors Chemistry, Chapter 2
Page 41
9
1.
2.
3.
Zeros Appearing Between Nonzero
Digits are Significant
Zeros Appearing in Front of All Nonzero
Digits are Not Significant
Zeros Appearing to the Right of the
Decimal Point And at the End of the
Number are Significant
Honors Chemistry, Chapter 2
Page 42
Rules for Significant Figures
4. Zeros at the End of a Number but to the
Left of the Decimal Point May or May Not
be Significant. If a Zero Has Not Been
Measured or Estimated but is Just a
Placeholder, it is Not Significant. A
Decimal Point Placed After Zeros
Indicates They are Significant.
Honors Chemistry, Chapter 2
Page 43
If the Digit Following the Last Digit to be
Retained is:
> 5Then Round Up
< 5Then Round Down
5 Followed by non Zero Digits
Then Round Up
Honors Chemistry, Chapter 2
Page 44
Rules for Rounding
If the Digit Following the Last Digit to be
Retained is:
5 Followed by Non-Zero Digit(s), and
Preceeded by an Odd Digit
Round Up
5 Followed by Non-Zero Digit(s), and
Preceeded by an Even Digit
Leave Unchanged
Honors Chemistry, Chapter 2
Page 45
 When
Adding or Subtracting Decimals,
the Answer Must Have the Same
Number of Digits to the Right of the
Decimal Point as There are in the
Measurement Having the Fewest Digits
to the Right of the Decimal Point.
Honors Chemistry, Chapter 2
Page 46
Significant Figures With
Multiplication/Division
• When Multiplying or Dividing, the Answer
Can Have no More Significant Figures
Than are in the Measurement with the
Fewest Number of Significant Figures.
• (Conversion Factors Have Unlimited Digits
of Accuracy.)
Honors Chemistry, Chapter 2
Page 47
The numbers reported in a
measurement are limited by the
measuring tool
Significant figures in a measurement
include the known digits plus one
estimated digit
RULE 1. All non-zero digits in a measured number
are significant. Only a zero could indicate that
rounding occurred.
Number of Significant Figures
38.15 cm
5.6 ft
65.6 lb
122.55 m
4
2
___
___
RULE 2. Leading zeros in decimal numbers are
NOT significant.
Number of Significant Figures
0.008 mm
1
0.0156 oz
3
0.0042 lb
0.000262 mL
____
____
RULE 3. Zeros between nonzero numbers are
significant. (They can not be rounded unless
they are on an end of a number.)
Number of Significant Figures
50.8 mm
3
2001 min
4
0.702 lb
0.00405 m
____
____
RULE 4. Trailing zeros in numbers without
decimals are NOT significant. They are only
serving as place holders.
Number of Significant Figures
25,000 in.
200. yr
48,600 gal
25,005,000 g
2
3
____
____
A. Which answers contain 3 significant figures?
1) 0.4760
2) 0.00476
B. All the zeros are significant in
1) 0.00307
2) 25.300
3) 4760
3) 2.050 x 103
C. 534,675 rounded to 3 significant figures is
1) 535
2) 535,000
3) 5.35 x 105
In which set(s) do both numbers contain
the same number of significant figures?
1) 22.0 and 22.00
2) 400.0 and 40
3) 0.000015 and 150,000
State the number of significant figures in each of
the following:
A. 0.030 m
1
2
3
B. 4.050 L
2
3
4
C. 0.0008 g
1
2
4
D. 3.00 m
1
2
3
E. 2,080,000 bees
3
5
7
A
calculated answer cannot be more precise
than the measuring tool.
 A calculated answer must match the least
precise measurement.
 Significant figures are needed for final answers
from
1) adding or subtracting
2) multiplying or dividing
The answer has the same number of decimal
places as the measurement with the fewest
decimal places.
25.2
one decimal place
+ 1.34 two decimal places
26.54
answer 26.5 one decimal place
The answer has the same number of decimal
places as the measurement with the fewest
decimal places.
25.2
one decimal place
+ 1.34 two decimal places
26.54
answer 26.5 one decimal place
In each calculation, round the answer to the
correct number of significant figures.
A. 235.05 + 19.6 + 2.1 =
1) 256.75
2) 256.8
3) 257
B. 58.925 - 18.2 =
1) 40.725
2) 40.73
3) 40.7
Round (or add zeros) to the calculated
answer until you have the same number
of significant figures as the
measurement with the fewest significant
figures.
A. 2.19 X 4.2 =
1) 9
2) 9.2
3) 9.198
B. 4.311 ÷ 0.07 =
1) 61.58
2) 62
3) 60
C. 2.54 X 0.0028
=
0.0105 X 0.060
1) 11.3
2) 11
3) 0.041
. l2. . . . I . . . . I3 . . . .I . . . . I4. .
cm
First digit (known)
=2
2.?? cm
Second digit (known) = 0.7
2.7? cm
Third digit (estimated) between 0.05- 0.07
Length reported
=
2.75 cm
or
2.74 cm
or
2.76 cm
In 2.76 cm…
• Known digits 2 and 7 are 100% certain
• The third digit 6 is estimated (uncertain)
• In the reported length, all three digits (2.76
cm) are significant including the estimated
one
. l8. . . . I . . . . I9. . . .I . . . . I10. .
cm
What is the length of the line?
1) 9.6 cm
2) 9.62 cm
3) 9.63 cm
How does your answer compare with your
neighbor’s answer? Why or why not?
. l3. . . . I . . . . I4 . . . . I . . . . I5. .
What is the length of the line?
First digit
Second digit
Last (estimated) digit is
cm
5.?? cm
5.0? cm
5.00 cm
Always estimate ONE place past the smallest mark!
 Move
the Decimal Point Left or Right Until
the Mantissa is Greater Than or Equal to
1.0 and Less Than 10
 Express the Number as: M x 10n
Where
n Represents the Number of Places the
Decimal Point was Moved, Positive if the
Decimal is Moved Left and Negative if the
Decimal is Moved Right
Honors Chemistry, Chapter 2
Page 67
Scientific notation is a way of expressing
really big numbers or really small
numbers.
 For very large and very small numbers,
scientific notation is more concise.


A number between 1 and 10

A power of 10
Nx
x
10



Place the decimal point so that there is one
non-zero digit to the left of the decimal point.
Count the number of decimal places the
decimal point has “moved” from the original
number. This will be the exponent on the 10.
If the original number was less than 1, then the
exponent is negative. If the original number
was greater than 1, then the exponent is
positive.
Given: 289,800,000
 Use: 2.898 (moved 8 places)
 Answer: 2.898 x 108

Given: 0.000567
 Use: 5.67 (moved 4 places)
 Answer: 5.67 x 10-4

Simply move the decimal point to the
right for positive exponent 10.
 Move the decimal point to the left for
negative exponent 10.

(Use zeros to fill in places.)
Given: 5.093 x 106
 Answer: 5,093,000 (moved 6 places
to the right)

Given: 1.976 x 10-4
 Answer: 0.0001976 (moved 4 places
to the left)


1)
2)
3)
4)
5)
Express these numbers in
Scientific Notation:
405789
0.003872
3000000000
2
0.478260
Y
= kX
 Example Mass vs. Volume Data for
Aluminum
 Slope of the Line (k) is the Density
Honors Chemistry, Chapter 2
Page 75
Block Number
1
2
3
4
5
6
7
8
9
10
Honors Chemistry, Chapter 2
Page 76
3
Mass (g) Volume (cm )
1.20
3.69
5.72
12.80
15.30
18.80
22.70
26.50
34.00
36.40
0.44
1.39
2.10
4.68
5.71
6.90
8.45
9.64
12.80
13.50
Mass (g) As a Function of Volume (V)
40
Mass - grams
35
30
25
20
Mass (g)
15
10
5
0
0
5
10
Volume - cubic centimeters
Honors Chemistry, Chapter 2
Page 77
15
Y
= mX + b
= slope x Volume + intercept
 Slope
= 2.69 g/cm3
 Intercept = 0.09 grams (!) (Actually Zero)
 From Table of Densities: Sample is
Aluminum (Al)
Honors Chemistry, Chapter 2
Page 78
k
= XY or Y = k/X
 As X Increases, Y Decreases
 Example: Pressure-Volume Data
Honors Chemistry, Chapter 2
Page 79
3
Pressure (k-Pa)
Volume (cm )
PxV
100
150
200
250
300
350
400
450
500
333
250
200
166
143
125
110
50000
49950
50000
50000
49800
50050
50000
49500
Honors Chemistry, Chapter 2
Page 80
Volume (cm3)
600
500
400
300
Volume (cm3)
200
100
0
0
200
400
Pressure (kPa)
Honors Chemistry, Chapter 2
Page 81
600
Chapter 2, Section 3 Review
1. Distinguish between accuracy and precision.
2. Determine the number of significant figures in
a measurement.
3. Perform mathematical operations (+,-,x,/)
involving significant digits.
4. Convert measurements into scientific notation.
5. Distinguish between inversely proportional and
directly proportional relationships.
Honors Chemistry, Chapter 2
Page 82