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Chapter One:
CHEMICALFOUNDATIONS
Contents
Atoms vs. Molecules
p031-1 Chemistry: An Overview
Oxygen and Hydrogen Molecules
p03
A Chemical Reaction
A Chemical Reaction
p04
Science: A Process for UnderstandingNature and Changes
p05
1. Making observations (collecting data)
2. Making a prediction (formulating a hypothesis)
3. Doing experiments to test the prediction (testingthe hypothesis)
1-2 The Scientific Methodp05
Steps in the Scientific Method
Making observations. Observations may be qualitative
(the sky is blue; water is a liquid) or quantitative
(water boils at 100℃; a certain book weighs 2
kilograms). A qualitative observation does not involve
a number. A quantitative observation called a
measurement ) involves both a number and a unit.
Formulating hypotheses. A hypothesis is a possible
explanation for an observation.
Performing experiments. An experiment is carried
out to test a hypothesis. This involves gathering
new information that enables a scientist to decide
whether the hypothesis is valid.
that is, whether it is supported by the new
observation learned from the experiment.
Experiments always produce new observations, and
this brings the process back to the beginning again.
The Various Parts of theScientific Method
P05
Figure 1.5
Law vs. Theory
A law summarizes what happens.
A theory (model) is an attempt to explain
why it happens.
1-3 Units of Measurementp09
1 liter = (1 dm)3 = (10 cm)3 = 1000 cm3
cdcandelaLuminous intensitymolmoleAmount of substanceAampereElectric currentKkelvinTemperaturessecondTimemmeterLengthkgkilogramMass
AbbreviationName of UnitPhysical Quantity
cdcandelaLuminous intensitymolmoleAmount of substanceAampereElectric currentKkelvinTemperaturessecondTimemmeterLengthkgkilogramMass
AbbreviationName of UnitPhysical Quantity
Table 1.1 The Fundamental SI Units
p9
p9
Nature of Measurement
Measurement - quantitative observation
consisting of 2 parts
Part 1 –number
Part 2 –scale (unit)
Examples:
20 grams
6.636.63 ×× 1010--3434 Joule seconds
Measure-ment ofVolumeUsing aBuret
p10
1-4 Uncertainty in Measurementp10
Uncertainty in Measurement
A digit that must be estimated is called
uncertain.
A measurement always has some degree of
uncertainty.
Ex 1.1 Uncertainty in Measurement
In analyzing a sample of polluted water, a chemistmeasured out a 25.00-mL water sample with a pipet. Aanother point in the analysis, the chemist used agraduated cylinder to measure 25 mL of a solution.What is the difference between the measurements25.00 mL and 25 mL?
Solution:
The quantity 25 mL means that the volume is between 24mL and 26 mL, whereas the quantity 25.00 mL meansthat the volume is between 24.99 mL and 25.01 mL. Thepipet measures volume with greater precision than doesthe graduated cylinder.
p11
The Difference Between Precision and Accuracy p12
Ex 1.2 Precision and Accuracy
To check the accuracy of a graduated cylinder, a studentfilled the cylinder to the 25-mL mark using waterdelivered from a buret and then read the volume delivered.Following are the results of fives trials. Is the graduatedcylinder accurate?
Solution:
The student has good technique. However, note that theaverage value measured using the buret is significantlydifferent 25 mL. It produces a systematic error.
p13
Rules for CountingSignificant Figures - Details
Nonzero integers always count as
significant figures.
3456 has 4 sig figs.
1-5 Significant Figures andCalculations
p13
Rules for Counting SignificantFigures –Details (continued)
Leading zeros do not count as significant
figures.
0.048 has 2 sig figs.
Rules for Counting SignificantFigures –Details (continued)
Captive zeros always count as significant
figures.
16.07 has 4 sig figs.
Rules for Counting SignificantFigures –Details (continued)
Trailing zeros are significant only if the
number contains a decimal point.
9.300 has 4 sig figs
150 has 2 sig figs.
Rules for Counting SignificantFigures –Details (continued)
Exact numbers have an infinite number
of significant figures.
1 inch = 2.54 cm, exactly
Ex 1.3 Significant Figures p14
Give the number of significant figures for each of thefollowing results.
a. A Student’s extraction procedure on tea yields 0.0105g of caffeine.
b. A chemist records a mass of 0.050080 g in an analysis.
c. In an experiment a span of time is determined to be8.050 x 10-3 s.
Solution:a. The number contains three significant figures.
b. The number contains five significant figures.
c. This number has four significant figures.
Ex 1.4 Significant Figures inMathematical Operations
p15
Carry out the following mathematical operations, andgive each result with correct number of significantfigures.
a.1.05 x 10-3 ÷ 6.135
b. 21-13.8
c. The following values ere obtained : P =2.560, T =275.15, and V = 8.8. Using R = (PV)/T todetermine the value of gas constant (R).
Solution:
1-6 Dimensional Analysis p16
Converting from One Unit to Another
p17
To convert from one unit to another, use the
equivalence statement that relates the two units.
Derive the appropriate unit factor by looking at the
direction of the required change (to cancel the
unwanted units).
Multiply the quantity to be converted by the unit
factor to give the quantity with the desired units.
Ex 1.5 Unit Conversions I
A pencil is 7.00 in long. What is its length in
centimeters?
p17
Solution:
In this case we want to convert from inches to
centimeters. Therefore, we must use the reciprocal of
the unit factor used above to do the opposite conversion:
cm17.8cm4)(7.00)(2.5in1cm2.54
in7.00
Ex 1.6 Unit Conversions II
p18
You want to order a bicycle with a 25.5-in frame. But
the catalog are given only in centimeters. What size
should you order?Solution:
Ex 1.8 Unit Conversion IVP19
The speed limit on many highways is 55 mi/h. What
number would be posted in kilometers per hour?Solution:
1.7 Temperature p20
Figure 1.11 The three major temperature scales.
Ex 1.13 Temperature Conversions p21
Normal body temperature is 98.60F. Convert this
temperature to the Celsius and Kelvin scales.
Solution:
C37.0F9C5
F66.6 00
00
a. The number of Fahrenheit degrees between
32.00F and 98.60F is 66.60F. We must convert
this difference to Celsius degrees.
b. Tk = Tc +273.15 = 37.0 + 273.15 = 310.2 K
1-8 Density p24
Ex 1.13 Determining Density
A chemist , trying to identify the main component of acomponent of a compact disc cleaning fluid, finds that25.00 cm3 of the substance has a mass of 19.625 g at 20℃.The following are the names and densities of thecompounds that might be the main component? Which ofthese compounds is the most likely to be the maincomponent of the compact disc cleaner?
Solution
This density corresponds exactly to that of isopropyl alcohol.
p24
1-9 Classification of Matter p25
Figure 1.13 The three states of water.
Structure of a Solid
Structure of a Liquid
Structure of a Gas
Simple Laboratory Distillation Apparatus
Figure 1.14
p27
The Organization of Matterp28
The Organization of Matter
The Organization of Matter
The Organization of Matter p28
Homogeneous Mixtures
Mixture vs. Solution
Mixture vs. Compound
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