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Scientific Processes

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Title: Scientific Processes


1
Scientific Processes
  • Day 1
  • Scientific Method

Dr. Dutta
2
Science vs. Technology
  • Science is the knowledge gained from
    experimentation.
  • Newtons Laws
  • Theory of Relativity
  • Ohms Law
  • Human Genome Project
  • Technology is the use of science knowledge to
    make things.
  • Calculators computers
  • Atomic Energy
  • Electric motors
  • Gene therapy
  • Antibiotics

3
A Brief History of Science
  • Ancient Greek and Roman philosophers began
    observing and recording their observations of the
    world around them.
  • They tried to propose how and why these things
    occurred.

4
What is Chemistry?
  • Chemistry
  • The study of the composition of matter and the
    changes that matter undergoes.
  • Many everyday applications
  • Clothing
  • Pots and Pans
  • Cosmetics
  • Etc.

5
Branches of Chemistry
  • Organic Chemistry
  • Study of essentially all substances containing
    carbon.
  • Inorganic Chemistry
  • Studies primarily substances that do not contain
    carbon.
  • Nonliving things.
  • This class is mostly inorganic chemistry.
  • Analytical Chemistry
  • Studies the composition of substances.
  • Finding minute quantities of a medication in
    blood

6
Branches of Chemistry, cont.
  • Physical Chemistry
  • Concerned with the theories and experiments that
    describe the behavior of chemicals.
  • The stretching of nylon can be explained by using
    the concepts of physical chemistry.
  • Biochemistry
  • Studies living organisms.
  • For example digestion, blood clotting,
    respiration, and photosynthesis
  • All of these branches overlap to a degree you
    cannot study organic and biochemistry without
    using analytical.

7
Where do we find Chemistry?
  • Manufacturing materials
  • Providing Energy
  • Not just for our homes, but also for plants and
    animals.
  • Medicine and Biotechnology
  • Agriculture
  • The Environment

8
Scientific Method (One logical approach to the
solution of scientific problems)
  • 1. Observe something
  • 2. State the Problem
  • 3. Form a Hypothesis
  • -Hypothesis must be testable or measurable
  • -morals, value of judgment cannot be tested
  • 4. Set Up (Design) an Experiment
  • -Safety must be considered planned for
  • 5. Record and Analyze Results/Data
  • - Making Inferences Making a prediction based
    on information that is provided.
  • -Includes looking for trends in data.
  • 6. Draw a Conclusion
  • Steps dont have to be in this order but they
    often are

Go to Section
9
Observations
  • Using your senses to obtain information directly.
  • Use only senses.
  • No inferences
  • Example Ice melting is not forming water, H2O,
    it is forming a clear liquid.

Hypothesis
A proposed explanation or reason for what is
observed. Why you feel that something is
happening an educated guess!
10
What if the data doesnt support the hypothesis?
  • Some very important discoveries occurred when the
    scientist was actually looking for something
    else. For example, some antibiotics.

11
When the hypothesis doesnt fit
  • 1. Make a new hypothesis, based on the
    observations.
  • 2. Make an inference. What could the data be
    showing, even if it is not DIRECTLY OBSERVABLE?

12
A scientist has hypothesized that theexistence
of life on Mars is likely becauseMarss
atmosphere is 95 carbon dioxide.
  • 36 Which question is valid in testing this
    hypothesis?
  • F Do most other scientists agree with the
    hypothesis?
  • G Could abiotic processes account for the carbon
    dioxide?
  • H What is the percent of argon compared to carbon
    dioxide in the Martian atmosphere?
  • J Have the scientists other predictions about
    Mars been validated?

13
Scientific Theory
  • Theories are based upon experimental data.
  • Confirmed by repeated experiments.
  • Modified as new information is gathered.

14
Scientific Law
  • Theories become Laws when nothing changes for
    hundreds of years.
  • Laws become theories again when new information
    changes them.

15
  • 5 The smell of an ammonia solution used to clean
    a floor can quickly be detected throughout a
    house. Scientists explain this phenomenon by
    theorizing that gas molecules from the ammonia
    are in continuous random high-speed motion,
    drifting rapidly and permeating the air. Which
    statement best demonstrates the strength of this
    theory?

16
  • A compares the ammonia movement to something
    known. A is good evidence!
  • B, I dont think so, it takes hundreds of years
    for scientists to agree on any theory.
  • C, Other theories are proposed all the time, so
    throw this one out.
  • D, Experimentation is always the preferred
    method, so this one is out, too.
  • Therefore, you were right! It is A!
  • A Scientists have observed tiny smoke particles
    moved by unseen particles in a rapid, irregular
    fashion.
  • B Scientists have unanimously agreed on this
    theory since Thomas Grahams experiments in the
    1820s.
  • C The possibility of another theory being formed
    to explain the phenomenon as well is very remote.
  • D Reason, as opposed to experimentation, is
    superior to any explanation found through
    chemical testing.

17
Scientific Method

Set Up a Controlled Experiment to test
Hypothesis 1. Have Two Groups a.
Control group all variables constant (the
same) b. Experimental group receives
the independent variable 2. Types of
Variables a. Control variables all variables
that are kept the same in all groups b.
Independent variable the variable that is
changed (by the experimenter) in the group c.
Dependent variable variable that changes as a
result of the independent variable 3. Only
test one variable at a time in an experiment
Go to Section
18
Variables - DRY
  • Dependent or Responding variable is second
    column in a data table, and plotted on the Y-axis
    of a graph.

19
Variables MIX
  • Manipulated or Independent Variable is the one
    you are changing and is first in a data table and
    plotted on the X-axis of the graph.

20
Hypothesis
  • 1. Hypothesis must be testable or measureable
  • 2. Anything that is considered a moral, value
    or judgment cannot be tested

This statement is a poor hypothesis because it is
not A a question B testable C observable D a
comparison
Correct answer B This statement cannot be
measured it is an opinion!
21
Selecting a Correct Hypothesis
  • In an activity, a ball is dropped from a
    height of 100 cm onto five different materials.
    The rebound height of each drop is shown in the
    graph. Which of the following describes the
    hypothesis most likely being tested?

Independent variable Dependent variable
A The mass of the ball affects the rebound
height. B The material the ball is made of
affects the rebound height. C The height the
ball is dropped from affects the rebound
height. D The surface the ball is dropped
onto affects the rebound height.
(X-axis) Surface / Material the object is bounced
against
(y-axis) How high the object bounces
Correct answer D matches our prediction
22
Identifying variables
16. A medical researcher hypothesizes that a
newly developed medication can reduce high blood
pressure. Which of these would most likely be the
dependent variable in a study involving this
medication?
  • A The number of participants in the study
  • B The ages of people treated for high blood
    pressure with other medications
  • C The blood pressure of the participants in the
    study
  • D The number of people treated for high blood
    pressure with other medication

Independent variable Dependent variable
New developed medicine
Blood pressure
Correct answer C matches our prediction
23
  • The graph compares absenteeism of elementary
    school students who wash their hands properly
    with absenteeism of students who fail to wash
    their hands properly. Which inference could best
    be supported by these data?

F Proper hand washing may increase
attendance among elementary school students.
G Older students have developed better
hand-washing habits than younger students
H Some elementary school classes teach
correct hand-washing methods to students J
Improper hand washing is a common practice
among most elementary school students
What can you tell by just reading the graph?
Kids miss less school if they wash their hands
correctly.
Correct Answer F Best matches our initial
answer!
24
Analyzing Promotional Claims
Correct answer D
  • Which conclusion about AvexTec is supported by
    information in this advertisement?
  • A AvexTec is available over the counter at local
    pharmacies and grocery stores.
  • B People who take AvexTec every day will seldom
    experience pain from migraines.
  • C Research indicates that AvexTec prevents
    migraine headaches.
  • D AvexTec can be prescribed to reduce pain from
    migraines.

25
Tools for Measurement
Clocks and stopwatches measure time. A balance
is used to measure mass. A graduated cylinder,
dropper, or volumetric flask is used to measure
volume.
26
Description(Qualitative) vs. Number(Quantitative)
Number vs. Quantity
  • Quantity - number unit

UNITS MATTER!!
27
SI Units
Quantity
Base Unit
Symbol
Length
meter
m
Mass
kilogram
kg
Time
second
s
Temp
kelvin
K
Amount
mole
mol
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Accuracy vs. Precision
  • Accuracy - how close a measurement is to the true
    value
  • Precision - how close a set of measurements are
    to each other

ACCURACY CORRECTNESS PRECISION CONSISTENCY
30
Percent Error
  • Indicates accuracy of a measurement.

31
Percent Error
  • Julie determines the density of copper to be 8.25
    g/cm3. Find the error if the actual density of
    copper is 8.92 g/cm3.

32
Precision
  • This is the repeatability of a measurement.
  • It may or may not be accurate
  • But everyone who does it gets the same answer

33
Accuracy vs. Precision
  • Which of the following will allow measurement of
    a liquids volume with the greatest precision?
  • A 50 mL cylinder graduated in 1 mL increments
  • B 50 mL cylinder graduated in 0.5 mL increments
  • C 100 mL cylinder graduated in 1 mL increments
  • D 200 mL cylinder graduated in 5 mL increments

Answer B
34
Derived Units
  • Combination of base units.
  • Volume - length ? length ? length
  • 1 cm3 1 mL 1 dm3 1 L
  • Density - mass per unit volume (g/cm3)

35
D. Density
  • Problem-Solving Steps
  • 1. Identify the problem.
  • 2. Plan a strategy.
  • 3. Execute the plan.
  • 4. Evaluate the results.

36
D. Density
  • An object has a volume of 825 cm3 and a density
    of 13.6 g/cm3. Find its mass.

GIVEN V 825 cm3 D 13.6 g/cm3 M ?
WORK M DV M (13.6 g/cm3)(825cm3) M 11,200
g
37
D. Density
  • 1) A liquid has a density of 0.87 g/mL. What
    volume is occupied by 25 g of the liquid?

GIVEN D 0.87 g/mL V ? M 25 g
V 29 mL
38
D. Density
39
Significant Figures
  • Indicate precision of a measurement.
  • Recording Sig Figs
  • Sig figs in a measurement include the known
    digits plus a final estimated digit

2.33 cm
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Pacific (Present)
Atlantic (Absent)
  • If the decimal is present, start on the Pacific
    side at the first nonzero digit and count it and
    all the digits to the right of it.
  • If the decimal is absent, start on the Atlantic
    side at the first nonzero digit and count it and
    all the digits to the left of it.

48
Significant Figures
Counting Sig Fig Examples
1. 23.50
1. 23.50
4 sig figs
3 sig figs
2. 402
2. 402
3. 5,280
3. 5,280
3 sig figs
2 sig figs
4. 0.080
4. 0.080
49
Measurement
  • Unit Conversions

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Significant Figures
Practice Problems
  • 5. (15.30 g) (6.4 mL)

? 2.4 g/mL
2.390625 g/mL
6. (18.9 g) - (0.86 g)
? 18.0 g
18.04 g
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Scientific Notation
  • Converting into Sci. Notation
  • Move decimal until theres 1 digit to its left.
    Places moved exponent.
  • Large (gt1) ? positive exponentSmall (lt1) ?
    negative exponent
  • Only write sig figs.

57
Scientific Notation
Practice Problems
2.4 ? 106 ?g
  • 7. 2,400,000 ?g
  • 8. 0.00256 kg
  • 9. 7 ? 10-5 km
  • 10. 6.2 ? 104 mm

2.56 ? 10-3 kg
0.00007 km
62,000 mm
58
Measurement
  • Unit Conversions

59
A. SI Prefix Conversions
  • 1. Find the difference between the exponents of
    the two prefixes.
  • 2. Move the decimal that many places.

60
A. SI Prefix Conversions
Prefix
Symbol
Factor
move left
move right
61
A. SI Prefix Conversions
0.2
  • 1) 20 cm ______________ m
  • 2) 0.032 L ______________ mL
  • 3) 45 ?m ______________ nm
  • 4) 805 dm ______________ km

32
45,000
0.0805
62
Dimensional Analysis
  • The Factor-Label Method
  • Units, or labels are canceled, or factored out

63
Dimensional Analysis
  • Steps
  • 1. Identify starting ending units.
  • 2. Line up conversion factors so units cancel.
  • 3. Multiply all top numbers divide by each
    bottom number.
  • 4. Check units answer.

64
Dimensional Analysis
  • Lining up conversion factors

1
1 in 2.54 cm
2.54 cm 2.54 cm
1
1 in 2.54 cm
1 in 1 in
65
B. Dimensional Analysis
  • 5) Your European hairdresser wants to cut your
    hair 8.0 cm shorter. How many inches will he be
    cutting off?

8.0 cm
1 in 2.54 cm
3.2 in
66
B. Dimensional Analysis
  • 7) A piece of wire is 1.3 m long. How many
    1.5-cm pieces can be cut from this wire?

1.3 m
100 cm 1 m
1 piece 1.5 cm
86 pieces
67
B. Dimensional Analysis
  • How many milliliters are in 1.00 quart of milk?

1.00 qt
1 L 1.057 qt
1000 mL 1 L
946 mL
68
B. Dimensional Analysis
  • You have 1.5 pounds of gold. Find its volume in
    cm3 if the density of gold is 19.3 g/cm3.

1 cm3 19.3 g
1.5 lb
1 kg 2.2 lb
1000 g 1 kg
35 cm3
69
B. Dimensional Analysis
  • How many liters of water would fill a container
    that measures 75.0 in3?

75.0 in3
(2.54 cm)3 (1 in)3
1 L 1000 cm3
1.23 L
70
B. Dimensional Analysis
  • 6) Taft football needs 550 cm for a 1st down.
    How many yards is this?

550 cm
1 in 2.54 cm
1 ft 12 in
1 yd 3 ft
6.0 yd
71
Data Collection and Sample Size
  • The larger the amount of data collected,
  • The larger the sample size,
  • The more times the experiment is repeated,
  • The more valid are the results.

72
30 An herbal company advertises that its product
will help people lose weight if they take a
tablespoon of the product with a glass of water
at bedtime each night. Weight loss is guaranteed
if a person does not eat for at least 3 hours
before bedtime, gets moderate exercise, and
drinks 8 glasses of water each day. Why is the
companys claim difficult to verify? F The
company has yet to disclose the identity of its
special herb. G Numerous uncontrolled variables
are involved in evaluating results. H Fasting
lessens the absorption rate of the herb. J The
advertisement lacks data from before and after
the weight loss.
Not eating before bedtime is recommended for all
weight loss programs, and it takes several hours
to digest and absorb anything you take so this
statement is invalid
True, but you wouldnt expect them to.
True, and also correct!!
True, but still doesnt control any of the other
factors.
73
Analysis of the Data
  • Data tables, flow charts and graphs present the
    information collected during an experiment.
  • What the data shows, any trend in information is
    explained in the analysis of data.

74
31 An environmental-science company measured the
ozone pollutant levels at two different locations
in a metropolitan area. Which statement is best
supported by these data?
Look for the unsafe levels and where and when
they occur.
75
Both occurred on 7/15 at a temperature of 38 oC,
so . .
  • A Lower fuel efficiency and northerly winds in
    the winter increase ozone pollution the most.
  • B Northwest winds in the spring transport ozone
    pollution into the metropolitan area.
  • C High summer temperatures and southerly winds
    contribute to high levels of ozone.
  • D Heavy use of automobiles changes ozone levels
    the most.

winter
spring
This is true, however not supported by the data
in the table since both downtown and northwest
areas had increases.
76
Data Presentation and Analysis
  • Data tables are lists of information that may or
    may not show a relationship.
  • Graphs are pictorial representations of
    information to aid in seeing any relation between
    them.

77
Data Tables
  • The first column is usually the independent
    variable, or what was being changed.
  • Other columns are counts or measurements that
    were taken at each change.

78
22 The table shows environmental factors and
soybean production for three regions.
79
Which of the following probably accounts for the
decrease in soybean yield in Region 1?
  • F High levels of ozone damaged the soybean
    plants, decreasing the average yield.
  • G Low rainfall amounts failed to meet the plants
    moisture needs and inhibited growth.
  • H Poor mineral levels found in the soil in that
    region limited the soybean harvest.
  • J Higher-than-normal rainfall increased pest
    activity, decreasing the average yield.

80
What do you have to know?
  • 1st you really only have two choices, decreased
    rainfall, or O3 level.
  • Since the rainfall did not decrease consistently
    (it actually increased in 1999) that would not be
    a good answer.
  • Therefore, it must be the O3, which is the
    chemical formula for ozone.
  • Answer?

F
81
Reading Graphs
  • Always read the title.
  • Read the x- y-axis labels UNITS.
  • What is happening?
  • As the pressure of oxygen increases, the
    saturation is increased.

82
Graph Types Pie and Bar
Pie Graphs are used to show parts of a whole and
percent distributions. Bar Graphs show
noncontinuous data such as number of males and
females in each science class with different hair
colors.
83
Graphs Line or Curves
  • Line Graphs show continuous data like distance
    vs. time, acceleration, or plant growth over 6
    weeks

84
Data Trends
  • Direct relationship means as one variable
    changes, the other changes in the same way.

85
Other Data Trends
  • Inverse when one goes up the other one goes
    down or as one goes down the other goes up.
  • Exponential typical of uncontrolled growth of a
    population, is a J-shaped curve

86
47 Which graph best shows the comparison of the
elements to the total composition of the copper
ore?
87
This is noncontinuous data (not time or
temperature or increasing forces) and it is in
percentages. D is a pie graph which shows
percentage parts of the whole!
88
Drawing conclusions
  • Not getting the results expected, or predicted
    often provides more information than getting what
    you expected.
  • Ernest Rutherford did not expect his light to go
    straight through the gold foil, but it showed him
    that atoms were mostly empty space. A very
    important discovery.

89
7 Many doctors recommend 800 µg of folate, 400 µg
of vitamin B12, and 50 mg of vitamin B6 per day
to improve cardiovascular health. Based on this
information and the nutrition label, the
cardiovascular health benefit of a 1-ounce
serving of this cereal is
90
  • Since the question asks about the nutritional
    value based on Folate and the B vitamins,
    evaluate the answers based on the same
    information.
  • B is not valid since no information is given as
    to what are good levels.
  • C is not valid as it does not provide all the
    vitamins.
  • D is not a valid answer since it is very low in
    fat.
  • ANSWER A
  • A doubtful because it provides insufficient
    folate and vitamin B6 and lacks vitamin B12
  • B superb because it contains only 22 g of
    carbohydrates and 75 mg of sodium
  • C excellent because it provides all needed
    vitamins and is low in fat and cholesterol
  • D poor because it raises blood cholesterol levels
    with its high fat and cholesterol content
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