Chemistry grades 10 -12 Grade Level/Subject
Unit
Enduring Understanding
SOL Standards
Experimentation/Measurement – topics include Density and Sig Figs
I.
Density is a linear relationship between mass and volume. It is an intrinsic property that can be used to identify and characterize unknown substances.
II.
Significant Figures of a measurement are the number of known digits together with one estimated digit – these are derived from the precision of the instrument used.
III.
Repeated trials during experimentation ensure verifiable data.
IV.
Graphs are used to summarize the relationship between variables and can be used to predict how these variables will interact under new conditions.
Standard CH.1 – The Students will investigate and understand that experiments in which variables are measured, analyzed and evaluated produce observations and verifiable data.
The Graduated Cylinder Challenge Title
Lesson Objective
2
I.
Students will practice measurement skills using a graduated cylinder and mass balance to precisely measure the mass and volume of an unknown solution.
II.
Students will use their data analysis and knowledge of density to determine the mass of the empty graduated cylinder
Inquiry Level
Materials Required Graduated Cylinders (variety of sizes – 50 or 100mL works best)
Solution A (3.4 M NaCl) – at least 100 mL per Group
Solution B (0.5 M Sucrose) – at least 75 mL per Group
Mass Balance (only need one or two)
Food Coloring
*Adapted from an activity published by Flinn Scientific (2012).

The purpose of this level two-inquiry lab is to reinforce the concept of density. Students will practice measurement skills using a graduated cylinder and mass balance to precisely measure the mass and volume of an unknown solution.
What makes this lab an inquiry lab is the challenge – students will use their data analysis and knowledge of density to determine the mass of the empty graduated cylinder. The accuracy of their prediction will be used to grade the lab – this high stakes scenario motivates and engages student.
GRADE LEVEL/SUBJECT:
PREREQUISITE KNOWLEDGE:
UNIT:
SOL OBJECTIVES:
First Year Chemistry Course (10 th -11 th Grade)
Density, Graphing, and Linear Relationships
Experimentation/Measurement – topics include Density and Sig Figs
Standard CH.1 – The Students will investigate and understand that experiments in which variables are measured, analyzed and evaluated produce observations and verifiable data.
LEVEL OF INQUIRY: Level Two – Question and Methods are Given, Solution is Open.
MATERIALS REQUIRED:
TIMING:
Graduated Cylinders (variety of sizes – 50 or 100mL works best)
Solution A (3.4 M NaCl) – at least 100 mL per Group
Solution B (0.5 M Sucrose) – at least 75 mL per Group
Mass Balance (only need one or two)
Food Coloring
Data Collection ~25 minutes
Analysis and Post Lab ~45 minutes
ESSENTIAL UNDERSTANDINGS
 Density is a linear relationship between mass and volume. It is an intrinsic property that can be used to identify and characterize unknown substances.
 Significant Figures of a measurement are the number of known digits together with one estimated digit – these are derived from the precision of the instrument used.
 Repeated trials during experimentation ensure verifiable data.
 Graphs are used to summarize the relationship between variables and can be used to predict how these variables will interact under new conditions.
TO PREPARE FOR THE LAB…
 Prepare enough Solution A and Solution B for each lab group. Use food dye to color each solution a different color for easy identification and better visibility when taking measurements.
Mass of Solute
200 g of NaCl (Table Salt)
Volume of Solution
1 Liter of Tap Water
Concentration
3.4 Molar
170 g of Sucrose (Sugar) 1 Liter of Tap Water 0.5 Molar
 Collect and clean graduated cylinders. It is best to use different types of cylinders if you own them – so that students can’t compare their solutions. If all your cylinders are the same, differentiate the weight by adding a small amount of modeling clay to the base of each cylinder. You could also tie ribbon or wrap a small piece of metal wire around the base as well.
 Set out 1-2 mass balances in an area that you can supervise. Avoid given each group a balance – you do not want them secretly checking the mass of the empty cylinder.
Name: __________________________________
Period: ________
*Adapted from an activity published by Flinn Scientific (2012).

In this lab, you will collect data for the mass and volume of a mystery liquid and graph the results. You will then learn how that graph can help you make accurate predictions. You will be graded on how closely your predictions match reality – therefore, be mindful of your lab technique and analysis as they both can significantly alter your score on this activity.
Important: Use the same graduated cylinder and balance throughout the lab.
1. Pour 10 mL of liquid A into your graduated cylinder; record the precise volume in Data Table A. Remember sig figs!
2. Weigh the cylinder and liquid on one of the balances at the front of the room. Record this mass in the data table.
3. Repeat steps 1 and 2 four more times, for a total of five volume and mass readings, each time adding more liquid to the cylinder. Do not dump out solution between trials. Record your data in the table below.
4. When you have finished five trials, pour liquid A back into the flask from which it came. Rinse the graduated cylinder and repeat steps 1-3 for liquid B.
5. Use your data to create a graph of mass vs. volume. There should be two separate data series – one for liquid A and one for liquid B. Make sure to distinguish them with a key/colors or shapes. Use a ruler to carefully draw a best-fit straight line through each data series. (Ignore any obvious outliers.) Extend this line across the entire graph grid. Then use your best-fit line to make the following predictions. GRAPH PAPER ON BACK – make sure to include a title, key and labels.
A.
Predict how much the empty graduated cylinder weighs
6. Record your prediction in below (include the units and sig figs). Hint: there is a point on your graph that will help you determine the empty mass!
Be as precise and accurate as you can. Your grade is based on how close your prediction is to the actual mass (See Scoring Table below).
7. Once you have written down your prediction in the space below, dry out your graduated cylinder and hand it (and this sheet) to your instructor.
He/she will weigh it (on the same balance you have been using), and then record the actual mass and your score.
B.
Predict how much the cylinder will weigh with 50.0 mL of liquid A
8. Again use your graph to determine this prediction and record below (include the units and sig figs).
9. Once you have written down your prediction in the space below, pour precisely 50.0 mL of liquid A into the cylinder and hand it (along with this sheet) to your instructor, He/she will weigh it, and then record the actual mass and your score.
C.
Predict what volume of liquid A must be added to the cylinder to give a total mass of 95.00 g
10. Record your prediction in below (include the units).
11. Add precisely this much liquid A to the cylinder then hand it to your instructor. He/she will weigh it and then record the actual mass and your score.
12. Rinse out and dry your cylinder.
D.
Determine the density of liquids A and B
15. To determine the density of liquid A, you must understand what the “slope” of a line is. Slope is defined as how much a line goes up divided by how far it goes over. This is sometimes called “rise over run,” and for a graph it is defined as the change in y -value divided by the change in x -value.
Since our graph has mass plotted on the y -axis and volume plotted on the x -axis, the slope will be the change in mass divided by the change in volume. Think about how this relates to density. a) Pick any two points on the line for liquid A. Don’t use your data points; just use any points on the best-fit line. Try to use points that are pretty far apart and that are easy to read. b) Record the volume and mass for the higher point in Data Table D. c) Record the volume and mass for the lower point. d) Subtract the volumes to get the change in volume, Δ V. e) Subtract the masses to get the change in mass ( Δ m) and record this value.
*Adapted from an activity published by Flinn Scientific (2012).

f) Divide: This is the slope of the line, and it is also the density of liquid A, Δ m/ Δ V. Record the density of liquid A.
16. Repeat steps 15a–f, using the best-fit line for liquid B. Record results in Data Table D.
Data Table A: Mass and Volume Measurements of Solution A
Trial
1
2
Volume (mL) Mass (g)
3
4
5
Data Table B: Mass and Volume Measurements of Solution B
Trial
1
2
3
4
5
Data Table C: Predictions from Parts A, B & C
Mass of Empty Graduated Cylinder
Volume (mL)
Predicted Mass or Volume Actual Mass
Mass (g)
Difference
Mass of 50.0 mL of Solution A
Your Score
Volume of 95.00 g of Solution A
Data Table C
2
: Scoring Guide to be Used with Predictions
Degree of Error (within…)
0.5 g
1.0 g
2.0 g
3.0 g
5.0 g
10.0 g
Score
5.0 Points
4.5 Points
4.0 Points
3.5 Points
3.0 Points
2.0 Points
You Tried
Data Table D: Data from Graph of Mass vs. Volume used to determine Density of Solution A and Solution B
V
1
(mL) m
1
(g) V
2
(mL) m
2
(g) Δ V (mL)
1.0 Points
Δ m (g)
Solution A
Solution B
*Adapted from an activity published by Flinn Scientific (2012).
Density

1.
Look back at your graph of mass vs. volume, if the slope of the best-fit line for Solution A was steeper – would the density change? If so, describe how?
2.
On your graph, draw a new line to represent Solution X – which has a density that is less than Solution A and Solution B. Label this line and calculate the density as you have drawn it.
3.
Is it possible to change the density of a solution by changing the volume? For example, does 1 mL of Solution A have the same density as 5 mL of Solution B? Why or why not?
4.
How many significant figures should have been recorded for the graduated cylinder and for the mass balance? Label the certain and estimated digits below. Also determine which measurement was more precise?
Example
Measurement
What digits were certain?
What digits were estimated?
Which measurement is more precise? (check one)
Mass from Mass Balance
Volume from Graduated Cylinder
5.
Can you determine the accuracy of a measurement just by considering how many significant figures it contains? Why or why not?
6.
Errors that can be reliably estimated by repeating an experiment are called random errors. Random error is often the result of the experimenter
– for instance, had they been more careful, the error may not exist. Brainstorm with your group and determine at least two random errors that could have influenced the results of this lab. List them below and describe how they could have changed your prediction.
7.
Systematic errors are associated with flaws in the equipment or design of the experiment. Systematic errors cannot be estimated by repeating
*Adapted from an activity published by Flinn Scientific (2012).

the experiment because the affect of the error will be replicated each time. For instance, if a stop watch is running slowly – multiple trials will not help identify this problem. Brainstorm with your group and determine at least two systematic errors that could have influenced the results of this lab. List them below and describe how they could have changed your prediction.
*Adapted from an activity published by Flinn Scientific (2012).

*Adapted from an activity published by Flinn Scientific (2012).