# Unit 1

```Youngstown City Schools
SCIENCE: CHEMISTRY
UNIT #1: SAFETY / SCIENTIFIC METHOD / MEASUREMENTS (20 DAYS) 2013-2014
SYNOPSIS: This unit has a focus on safety that has students identifying and applying appropriate safety precautions in
the laboratory and in scientific investigations. Students investigate how chemistry is studied using the scientific method.
Students learn about the system of measurement units used by scientists and about expressing and dealing with the
numbers that result from scientific measurements. Using safety principles and laboratory equipment techniques, students
determine the density of an unknown substance.
ENABLERS: Safety, laboratory equipment, scientific method, metric system, English-metric conversions, density, physical states of
matter, physical and chemical properties, physical and chemical changes, pure substances, elements, compounds, mixtures
STANDARDS
I. SAFETY, SCIENTIFIC METHOD, AND MEASUREMENTS
A. proper use and identification of laboratory equipment
B. proper use of safety equipment (e.g., fire extinguisher, eye wash station, first aid kit)
C. proper first aid procedures for accidents (e.g., acid spills, cuts, burns, chemicals in eyes)
D. proper procedures for fires, waste disposal, broken glass, and unlabeled chemicals
E. use and understanding of MSDS sheets
F. identify questions and concepts that guide scientific investigations
G. design and conduct scientific investigations
1. Proper way of writing lab reports: objectives, procedures, data tables, sample calculations, concluding
questions
2. Safely use a variety of tools (e.g., hand tools, measuring instruments, calculators, and computers)
H. use technology and mathematics to perform and improve investigations and communications
I. formulate and revise explanations and models using logic and evidence (critical thinking)
J. recognize and analyze explanations and models
K. communicate and support a scientific argument
L. use correct scientific protocols for quantifying the properties of matter accurately and precisely
1. Derive and interpret data from mathematical relationships using graphs, charts, and tables
2. Apply mathematical concepts in problem solving (e.g., geometry, trigonometry, and logarithms
M. use metric measuring systems, significant figures, scientific notation, error analysis, and dimensional analysis
1. Demonstrate difference between precision and accuracy
2. Apply rules of significant digits and use correct units of measurement
3. Mathematically determine metric and temperature conversions
4. Experimentally determine the density of specific substances
5. Read and understand graphs, charts, and tables
LITERACY STANDARDS
RST 2:
Determine the central ideas or conclusions of a text; summarize complex concepts, processes, or information
presented in a text by paraphrasing them in simpler but still accurate terms.
WHST 10: Write routinely over extended time frames (time for reflection and revision) and shorter time frames (a single sitting
or a day or two) for a range of discipline-specific tasks, purposes, and audiences
MOTIVATION
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TEACHER NOTES
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TEACHER NOTES
MOTIVATION
1. Students watch the video “Safety in the Laboratory” Students keep a list of correct and safe
procedures. Students formulate questions for class discussion.
2. Teacher shows students how their notes are to be taken and how they will be “evaluated;”
explain that students will be asked not only to record key information but write reactions and
reflections like a scientist would write, as per designate tasks, audiences, and purposes.
3. Students set personal and academic goals. Since this is the first unit, teacher models how to
do this; offer samples from which students select and record for reference at the end of the
unit
4. Preview for students what the Authentic Assessment will be and what they will be expected to
do.
5. Students practice using the laboratory equipment (e.g. measuring the volume of water in a
graduated cylinder, measuring the mass of objects using a triple beam balance, measuring
temperature with a thermometer).
TEACHING-LEARNING
TEACHER NOTES
1. Teacher demonstrates the use of safety equipment in the classroom such as the fire
extinguisher, eye wash station/shower, chemical spill kits, emergency gas shut off valve.
Students take notes and record questions in notes. [IA, IB, ID, IE]
2. Teacher discusses scenarios and procedures for chemical and fire burns. Teacher discusses
fire drill procedures and demonstration of Bunsen burner with safety pin removed. Students
watch and write questions as they occur. Students take notes as instructed. Students record
key information and reactions. [IC]
3. Students take the Safety Test and sign the Safety Contract.
4. Students perform activity Light a burner (attached on page 5). Teacher supervises the
activity and watches safety procedures. Correct any safety issues immediately. Class
discussion follows. [IA-D]
5. Students examine MSDS sheet and information (attached on page 6). Follow with class
discussion [IE].
6. Teacher explains concepts that guide scientific procedures and the scientific method.
Students take notes and make comments or write questions in their notes as previously
directed. [IF]
7. Students are given equal amounts of paper and masking tape. Students apply the ideals of
the scientific method by designing and constructing a 6-foot free-standing tower out of the
paper and masking tape while working in pairs. [IF – IK]
8. Teacher checks for pre-understanding of metric measurements by forming student groups.
Each group is assigned different quantities (length/distance, weight, volume, time,
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TEACHING-LEARNING
TEACHER NOTES
temperature, electric current, potential difference, and heat). [IM] Students are asked to list
what units would commonly be used to express the quantity they have been assigned.
a. Length/distance: inches, feet, yards, miles
b. Weight: pounds, ounces, tons
c. Volume: gallons, cups, teaspoons, tablespoons, fluid ounces
d. Time: days, years, hours, minutes, seconds
e. Temperature: degrees Fahrenheit
f. Electric current: amperes
g. Potential difference: volts
h. Heat: British thermal units
9. Using pages 12-15 of the Holt Chemistry textbook, students identify the SI units of
measurement. Teacher explains conversion factors using the Skills Toolkit on page 13.
Students use the conversion factors to convert metric prefixes to English conversions.
Teacher discusses answers and procedures to correctly convert measurements. Use
remediation as necessary. [IM2 – IM3]
10. Students demonstrate temperature conversions (Fahrenheit, Celsius, and Kelvin) by solving
problems on the handout “Temperature Conversions.” Visit this website for example
http://www.teachengineering.org/collection/cub_/activities/cub_energy2/cub_energy2_
lesson06_activity1_tempconversionworksheet.pdf [IM3]
11. Students perform the Lab “Measurement and Significant Figures” (attached on pages 79) to demonstrate reading metric measurements on a meter stick, balance, and graduated
cylinder. Students keep careful records of data and gather in small groups to compare and
analyze data with other groups. Follow with class discussion. [IJ-K] [IM2 – IM3]
12. Students use outside sources (text, internet, etc.) to graphically illustrate the difference
between precision and accuracy. These are to be presented to the class. Teacher leads
discussion to clear up any misinformation. [IM1]
13. Teacher performs several demonstrations of density (e.g. density column, using density
blocks, etc.). Teacher explains concept of density (i.e., relationship between mass and
volume); students take notes (NOTE: do not tell students the density of water) [IM4]
a. demonstrate formula D = M / V
b. explain that mass is measured in kg (remind students about converting one metric
unit of mass or volume to another - - e.g., grams to kilograms and milliliters to liters,
etc.)
c. explain that volume is measured in mL and cm3
d. explain that density is a derived unit ( gram/cm3 or g/mL); explain density as “derived”
measure and show what this means. Students take notes following the format shown
earlier
14. Students perform the Labs “Density” and “Construction of a Graph,” (attached on pages
10-11) students learn to calculate slope; that density of water is 1g/mL; measure mass and
volume to calculate density; and to create a graph; students complete a lab report. Lab reports
will be returned and discussed as a class. [IH1] [IM4-5]
15. Teacher uses Prediction Guide to assess readiness by asking students to decide whether the
following statements are true or false: [IL – IM]
a. The terms accuracy and precision mean the same thing.
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TEACHING-LEARNING
TEACHER NOTES
b. It is important to write out all the digits of a number when answering chemistry
problems.
c. The number of digits written in an answer problem is important.
d. Scientific notation can be used for convenience.
e. Some values have an infinite number of significant figures.
16. Teacher explains the concept of significant figures and calculations using significant figures.
Students demonstrate expressing significant figures in calculations using their scientific
calculators. Students perform the Lab “Conversion Factors in Calculations.” ( Attached
on page 12-13) [IM2 – IM3]
17. Teacher models how to analyze scientific text to find central idea and trace the author’s
development of that idea through the text. Use A Basic Guide To Text Analysis (attached
on page 14). Article comes from the following website: http://science.nasa.gov/sciencenews/science-at-nasa/2007/08jan_metricmoon/ [RST.2]
on their own or in groups to determine the central ideas or conclusions of a text; trace the
text’s explanation or depiction of a complex process, phenomenon, or concept; provide an
accurate summary of the text (e.g., metrics in sports). [RST.2]
TEACHER NOTES
1. Unit Test: Multiple-Choice and 2-and 4-point response essays
TEACHER CLASSROOM ASSESSMENT
TEACHER NOTES
1. Safety Quiz
2. Lab Equipment Quiz (Students must score 80% or higher in order to pass.)
3. Lab reports or practical reports, using rubrics for quality points.
4. Assignments / worksheets
AUTHENTIC ASSESSMENT
TEACHER NOTES
1. Students evaluate their goals for the Unit.
2. Students devise a safety plan for the classroom in the case of an emergency chemical spill
or fire.
3. Students write the procedure to determine the density of an unknown substance (e.g. an
irregular solid or an unknown liquid); students use safe and proper laboratory techniques to
successfully identify the name of the unknown liquid
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Have students look at chemical containers MSDS sheets as this information is discussed.
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Measurements and Significant Figures Lab
Purpose: The aim of this lab is to practice recording measurements with the correct
number of significant figures.
Procedure:
1. Several stations have been set up around the room. Step up to a station, read the
directions, and read the measurement according to the directions. Record this
measurement with the correct units in the slot in your data table that corresponds to the
station number. Although you and your team mates may mass the objects together at
stations 4, 6, and 7, you must read the instruments yourself and should not copy a peer's
measurement.
Station #
1
Measuring tool
Measurement (with unit)
2
3
4
5
6
7
8
9
10a
10b
10c
11
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Discussion and Analysis:
1. Which stations required no approximation of the last significant figure? Why?
2. Did the estimations of you and your group mates always match? Why or why not?
3. Why is it important in lab activities to have one lab partner measure both the beginning
and final measurements for a specific tool?
Station 1: Meter stick
Directions: Measure the piece of paper in centimeters, being sure to estimate visually the last
readable number. Measure value to the nearest 0.01 cm.
Directions: Measure the liquid in the graduated cylinder to the nearest 0.1 mL, being sure to
estimate visually the place after the decimal. Record measurement to the nearest 0.1 mL.
Station 3: Buret:
Directions: Burets are measured from the top down. Be sure to honor this as you read the volume
of the liquid inside to the nearest 0.01 mL. Record this measurement in your table.
Station 4: Triple Beam Balance:
Directions: Adjust the balance to zero if necessary then place the object on the balance and
adjust the balance to accurately read the mass of the piece of metal. Record this measurement to
the nearest 0.01 g in your table. When you finish, remove the object and place the balance back to
zero.
Directions: Measure the liquid in the graduated cylinder to the nearest 1 mL, being sure to
estimate visually the place after the decimal. Discuss with your partner what each graduated line
means before measuring. Record measurement to the nearest 1 mL.
Station 6. Electronic balance:
Directions: Tare the balance to zero, check that the units are in grams and place the object on the
balance. When the measurement on the scale stabilizes, record the mass to the nearest 0.1 g in
Station 7: Analytical balance:
Directions: With glass doors closed, zero the balance. Open a glass door, place the metal on the
balance, close the door, and record the measurement once it equilibrates in your data table to the
nearest 0.001 g. Remove the metal when you finish and close the glass door.
Station 8: Ruler
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Directions: Measure the length of the metal cylinder to the nearest 0.01 cm. Record this
measurement under station 8 in your data table.
Station 9: Ruler
Directions: Measure the diameter of the metal cylinder to the nearest 0.01 cm. Record this
Station 10: Best for liquids
a. Record in your data table which of the three items would be best for measuring 9 mL of liquid.
b. Record in your data table which of the three items would be best for measuring 26 mL of liquid.
c. Record in your data table which of the three items would be best for measuring 155 mL of liquid.
Station 11: Thermometer
Directions: Read the temperature of the liquid to the nearest 0.1 degree and record this value in
your data table. Remember that the thermometer must remain in the liquid during the reading for
an accurate temperature.
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Density Lab
The density of a pure substance does not depend upon the amount of that substance. Like
temperature or melting point, density is an intensive property. That is, a ton of lead has the
same density as a milligram of lead (11.63g/cm3). Common units for density are grams per cubic
centimeter for solids, grams per milliliter for liquids, and grams per liter for gases. In this lab we
will work with solids.
Purpose:
To develop the formula for density from experimental data by graphical interpretation, and to
make comparisons in the densities of two different metals.
Materials:
Various sized graduated cylinder (10-100 ml)
6-8 metallic objects
centigram balances
Procedure:
1) Pick up a container holding 8-10 metallic objects. These objects are not marked. It will be the
duty of one person to be sure to keep track of which objects have massed and keep the process
orderly.
2) First determine the masses of each object by laying it on the balance pan and determining its
mass. Be sure that the metallic object is dry.
3) After each object's mass has been determined, carefully lower the metallic object in to a
graduated cylinder (choose a cylinder slightly larger than the piece, a 25 mL may work for all
pieces) containing an accurately measured amount of water. I suggest you have 5.0 ml of
water already in the graduated cylinder. Be sure that the metallic object is completely
submerged in the water before taking a new reading off the graduated cylinder. This method
of determining the volume of an irregularly shaped object is called volume displacement.
At the end of the writing is an example data table for you to use in recording your experimental
data.
Make a graph of mass versus volume. Record the mass along the vertical axis and the volume in
ml along the horizontal axis. Plot all data points on the graph. Give the graph a title; follow
accepted graphing procedures.
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Findings:
1. Is the origin (0,0) a valid point? Explain.
2. Draw a line or lines that best "fits" the data. The line or lines should be a straight line.
3. How many lines were plotted on the graph? What importance can be attached to this
observation to help make sense of the experiment?
4. The formula for a straight line is y=mx+b. What is the value (number reading) of b on your
graph? Since b = ____, the y = ____.
5. Substitute into the amended equation mass for y, and volume for x. Then solve for m, the slope
of the line.
6. Identify a physical property equal to the solution for m in question 4?
7. On your graph draw a perpendicular line form the 4-ml mark on the x-axis until it intersects the
plotted lines. From the point of intersections, draw a line that is perpendicular to the y-axis.
Using axis readings, determine the density represented by each slope?
8. Use the data table to determine the densities of each metal sample. How do these values
compare with the density values determined by reading the graph.
9. A liquid occupies 12.6 ml has a mass of 11.2 grams. Find the density of the liquid.
10. Write a summary that explains what you learned from doing this experiment.
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Name:
Date:
Measurement Conversions [Metric to English]
1. 74 cm = __________ in.
2. 25 ml = __________ tsp.
3. 50 kg = __________ lbs.
4. 160 km = __________ mi.
5. 3.6 l = __________ gal.
6. 500 g = __________ oz.
7. 100 m = __________ yds.
8. 300 ml = __________ cups.
9. 600 g = __________ lbs.
10.
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523 mm = __________ in.
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Name:
Date:
Measurement Conversions [Metric to Metric]
1. 3.68 kg = __________ g
2. 568 cm = __________ m
3. 8700 ml = __________ l
4. 25 mg = __________ g
5. 0.101 cm = __________ mm
6. 250 ml = __________ l
7. 600 g = __________ kg
8. 8900 mm = __________ m
9. 0.000004 m = __________ mm
10.
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0.250 kg = __________ mg
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