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TAKS Objective 1 The Nature of Science:

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TAKS Objective 1 The Nature of Science: Safety Equipment Measurement Scientific Method Safety Rules and Symbols Important Safety Terms Corrosive- Will corrode or eat ... – PowerPoint PPT presentation

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Title: TAKS Objective 1 The Nature of Science:


1
TAKS Objective 1 The Nature of Science
  • Safety
  • Equipment
  • Measurement
  • Scientific Method

2
Safety Rules and Symbols
3
Important Safety Terms
  • Corrosive- Will corrode or eat away metal, skin,
    or other substances. (acid or base)
  • Flammable (may ignite) - will catch on fire or
    explode easily
  • Volatile- Evaporates quickly, may form dangerous
    vapors (vapors may or may not be flammable)
  • Ventilation- removing contaminated air/vapors
    and bringing in fresh air (open windows or a use
    fume hood)
  • Dangerous vapors may cause
  • respiratory damage

4
Safety Rules The Big Ones
  • General Tie your hair back wear closed toe
    shoes
  • Diluting an Acid Pour acid into water slowly
    (PAWS)
  • Work with volatile chemicals only in a
    well-ventilated area or fume hood to remove
    vapors.
  • Wear goggles and an apron when working with
    chemicals, fire or glassware
  • Wear gloves when working with bacteria, living or
    nonliving specimens (treat as a biohazard)
  • Glassware heat Dont heat closed containers
    (pressure? can cause glassware to explode).
  • Heating Dont direct a test tube opening at
    anyone when heating it. (splattering or popping
    may occur)

5
Important Safety Symbols
A
Radioactive
B
C
Explosive
Corrosive
D
E
Flammable Volatile
Poison
F
Biohazard
6
Lab Safety
  • 1. Reactions that produce toxic gases should
    be performed in a
  • A laboratory fume hood
  • B beaker with a watch glass on top
  • C well-ventilated area of the lab
  • D warm, airtight drying oven

Should we breath in toxic gases? NO! How can we
trap/remove toxic gases?
Correct answer Choice A a lab fume hood will
trap the gases so that we dont breath in the
fumes from the toxic gases!
7
Lab Safety
What is the rule for mixing acid and water?
  • 2 The safest way to dilute concentrated sulfuric
    acid is to add
  • F a series of small volumes of water to the acid
    while stirring
  • G the acid to water slowly while stirring
    constantly
  • H the acid to a small volume of water and then
    add more water
  • J dilute sulfuric acid to a small volume of the
    concentrated acid

Correct answer G PAWSPour acid into
water slowly!
8
Lab Equipment
PRECISE / PRECISION Most exact measurement
varies for each measurement tool What
should we look for? -look for the
smallest/finest increments / scale
9
PRECISE / PRECISION
  • 9. Which of the following will allow measurement
    of a liquids volume (mL) with the greatest
    precision?
  • A. 50 mL cylinder graduated in 1mL increments
  • B. 100 mL cylinder graduated in 0.5 mL increments
  • C. 100 mL cylinder graduated in 1mL increments
  • D. 200 mL cylinder graduated in 5 mL increments

Which has the smallest increments?
Correct Answer B Using this graduated cylinder
with 0.5 mL increments will give you a more
exact/precise measurement of volume.
10
Volume
What units are used to measuring liquid
Volume______
mL
Beaker
Test Tube
Graduated Cylinder
Pipette
  • 10. Which of the above gives the most precise
    measurement?
  • 11. Which of the above should not be used to
    measure volume?

Pipette (smallest increments!)
Beaker- increments are too large give only an
approximate value Test Tube only used to test
or experiment with
11
Choosing Equipment
  • Which piece of equipment would be used to
    precisely measure the volume of an acid?

What are the key words?
Precisely want lots of increments Volume need
something that measures in mL
Correct answer Choice C because the graduated
cylinder gives a more precise measure than the
beaker.
Eliminate choice A (balance measures mass) D is
a Bunsen burner
12
Measuring Volume Accurately
46 mL
56 mL
Where is liquid volume read?
At the bottom of the curve called a meniscus.
13
Reading a Burette
What do we know?
  • Which is the best estimate of the volume of
    solution released from the burette?
  • A 47.3 mL
  • B 47.7 mL
  • C 48.3 mL
  • D 48.7 mL

Initial volume
Final Volume
0.8 mL
48.5 mL
Final volume Initial volume 48.5mL 0.8 mL
________
47.7 mL
Correct answer B
14
Triple Beam Balance Measures________ in___________
Grams (g)
Mass
How do you read the mass on these beams?
498.5 grams
14. Add beams together 400908.5 _______
Dont forget to subtract any mass of the
container that held any liquid or powders!
15
Scientific Method
16
Scientific Method
  • 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
17

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
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!
19
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
20
Testing Hypotheses
  • The following hypothesis refers to iron in
    the topsoil found on an island formed from
    limestone.
  • Which study would most likely be used to
    investigate this hypothesis?

F Tracking dust clouds with satellite
photos G Determining the effects of iron on
limestone H Calculating erosion rates in
African limestone mines J Analyzing the content
of comet dust clouds
How did the topsoil get on the island? Where
did the dust clouds come from?
Dust clouds carried by air currents
Answer F Best matches answers to questions
Africa
21
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
22
Experimental Design The Control Group
  • A valid study would include a control group
    containing

Groups
F bean seed, tomato seed, sunflower seed,
and water G water and 2 root hormone H water
only J bean seed, tomato seed, sunflower
seed, water, and 1 root hormone
Correct answer F
Concentration of root hormone
Independent variable ___________________________
Dependent variable _____________
Root growth
Control group
Whats missing? _______________
Bean seed, tomato seed, sunflower seed, water
added to control cup
What should the control group look
like?_________________________________
23
Making Inferences
  • Making a prediction based on information that
    is provided.
  • Includes looking for trends in data.

24
  • 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!
25
Promotional Claims
Can a product do what it claims it can do?
26
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.
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