University of Maine General Chemistry Lab (Fall 2021) 1

Polymers and Cross Linking: a CORE learning cycle lab1

After this experiment, you will be asked to write a formal lab report using a rubric at the end of

this lab handout and a Lab Report Template (F2019), which is available in the resource section

of ICN. To help you understand what is required, we will first ask you to write a draft lab report.

This draft will be your opportunity to assemble everything you need in your final report but

will not be submitted. Rather, you will bring this required draft the next time your lab section

meets, to work with other students and your TA during a Lab Report Workshop. Instructions

for the writing lab report workshop will be posted next week as a new assignment. In

summary:

(1) Conduct the Polymers and Cross-Linking Experiment (total = 100 pts)

- Prelab completed before the lab starts (20 pts)

- Create a draft: not submitted but is used the following week in Lab Report Workshop

- Submit the final lab report after the workshop (80 pts)

(2) Lab Report Workshop (total = 100 pts)

- Participation in Lab Report Workshop (75 pts)

- Bringing draft report (25 points) [If you do not bring your lab notebook and your draft

lab report, your TA will deduct 25 pts for your total]

Due to the highly interactive nature of the lab report workshop, it is generally not possible to

make up this lab. If you miss this lab, you may be able to attend another workshop session on a

different day during the same week that the workshop is given. However, this must be

coordinated through the lab manager (Dr. Sarah Bernard sarah.e.bernard@maine.edu). There is

no guarantee of making up this lab and you will not be able to make up this lab on an upcoming

day reserved for making up lab experiments.

University of Maine General Chemistry Lab (Fall 2021) 2

Introduction. This week, the laboratory experiment is designed using a learning cycle, which incorporates the use of a hands-on analogical model. The learning cycle, called CORE, stands for Chemical Observations, Representations, and Experimentation and was designed at the University of Maine (Avargil, Bruce, Amar, & Bruce, 2015; M. R. M. Bruce et al., 2016). The CORE learning cycle was designed to foster understanding of the chemistry occurring at the atomic scale by guiding students in making chemical observations, thinking about chemical observations in terms of representations, and designing experiments. The development of CORE has been supported by the National Science Foundation.(M. Bruce & Bruce, 2016-2020) These labs involve a higher level of inquiry than a lab designed around a predetermined recipe (or procedure). The CORE labs have been developed in response to a need for introducing higher levels of inquiry into introductory chemistry laboratory courses to better prepare students for careers in various STEM (Science, Technology, Engineering, and Mathematics) fields (President's Council of Advisors on Science and Technology, 2012).

The CORE Learning Cycle. There are 3 phases in the CORE learning cycle as illustrated in the diagram. Phase 1: Following a procedure, you and your partner will make observations about a chemical phenomenon. Phase 2: Next, you will work through an analogical modeling activity to consider a concept that is familiar and compare it to a chemical concept that is unfamiliar.

An analogy is a comparison between two domains: an analog concept that is familiar, and a target concept, which may be new or unfamiliar. An example of an analogy is that an electric battery (target) is like a reservoir of water (analog). The meaning of this analogy is derived by the feature that, in both domains, potential energy is stored and released to provide power for systems. This analogy is useful for understanding features of storing energy despite the fact that the average battery differs from the average reservoir in size, shape, color, and substance.

During Phase 2, you are asked to think about how the analogical model is useful and also in what ways the analogy has limitations. The purpose of Phase 2 is to help you understand the chemistry observed in Phase 1 and then apply that understanding in the next phase. Phase 3: Last, you will be asked to apply your understanding of the chemical phenomenon by designing an experiment to answer a scientific question. You and your partner will then go back into the lab to conduct your experiment and gather evidence. Designing and carrying out your own experiments can be challenging and requires careful thought.

Lab Overview

In this lab, you will synthesize and investigate the physical properties of a cross-linked polymer called “Slime” and determine how the physical properties relate to Slime’s molecular structure. You will use an analogical model to think about how changes in molecular structure (at the submicroscopic

level) affect the physical properties of a substance that you can observe (at the macroscopic level). Then, you will design an experiment to test your predictions based on your observations and consideration of the analogical model. Please read the introductory material and lab instructions and complete the pre-lab assignment on page 4 before coming to the laboratory.

Phase 3: Design, perform, and

analyze experiment to refine understanding

Phase 2: Use analogical reasoning to investigate

chemical concepts

Phase 1: Make observations about a chemical

phenomenon

University of Maine General Chemistry Lab (Fall 2021) 3

Introduction

At this moment, you are probably wearing or carrying at least half a dozen materials that did not exist 60 years ago. Parts of your shoes, clothes, pen, and computer are all made from materials that were first created synthetically in a chemistry laboratory. Many of these materials are polymers, long chains of repeating individual molecules (monomers) linked together by a chemical reaction. Polymers often have remarkably different physical properties when compared with the monomers that create them. A hallmark of a chemical reaction is that the product can have different physical properties than the reactants. Polymers can react with numerous reagents (other chemicals) to synthesize new materials with desired material properties. Often in these reactions another chemical is used to link polymer chains together. Molecules that can link or connect polymer chains together are called cross-linkers. The new product that forms after cross-linking will have different physical properties compared to either of the original reactants, thanks to its unique molecular structure. In this lab, you will investigate the chemical reaction between the polymer, polyvinyl alcohol and the cross-linker, sodium borate. The borate molecules will cross-link the individual chains of polyvinyl alcohol at various locations, resulting in a number of new chemical connections between the linear polymer chains. When sodium borate cross-links polyvinyl alcohol, a new polymer with unique properties (compared to either of the chemicals that were used to make it) forms. You will explore an analogical model with paper clips to help you understand the molecular structure and resulting physical properties of the two reactants, polyvinyl alcohol and sodium borate, as well as the product of their reaction, Slime. Paper clips will be used to represent monomers, the individual units of a polymer. When you link paper clips together in a linear chain, you will be building a representation of polyvinyl alcohol. (Your chain will be very short compared to an actual polyvinyl alcohol polymer. Polymer molecules can be many thousands of units long). You will use a different color paper clip to represent the sodium borate, forming links between the long chains of paper clips. We understand that this model is "simple", and this is by design. We are using it to convey how analogical reasoning can help you develop and refine models. This thinking process is how scientists develop much more complex models. Analogical reasoning is essential in chemistry (and the other sciences)

We cannot use our senses to observe atoms or molecules at the submicroscopic level. However, chemical interactions and structural features occurring at the submicroscopic level profoundly influence the way materials behave at the macroscopic level. However, the ability to “visualize” the structure and interactions of molecules is necessary for predicting and understanding how substances interact with one another to form new products. Chemists use a variety of ideas to think about chemical interactions at the submicroscopic level. For example, they draw chemical structures, build ball and stick models of molecules, or manipulate computer simulations. Analogical models, in particular, can help with visualizing molecular interactions. They allow us to imagine and explore how invisible chemical processes resemble tangible, real-world things. Many famous scientists (e.g., Albert Einstein, Robert Oppenheimer, and Richard Feynman, to name a few) reported using analogical reasoning to come up with predictions and explanations about abstract scientific phenomena in order to make sense of theoretical and experimental results. Thinking about the invisible chemistry and abstract chemical concepts is not trivial and analogical reasoning requires skill. Even if you are already familiar with the chemical concepts under investigation, using analogical models can deepen your understanding, especially if you consider both the strengths and weaknesses of a model. By posing questions about phenomena, you can develop ideas that can be tested to deepen understanding.

University of Maine General Chemistry Lab (Fall 2021) 4

The process of science

Chemists often start with questions in response to experimental observations. They formulate an explanation based on their current understanding of the phenomena they have observed. Then they design experiments in an attempt to test whether or not their explanation can be supported. The results of experiments can be carefully analyzed and compared to see if they provide evidence to support the explanation. If the evidence suggests the explanation needs to be altered, a refined explanation can be formulated. This process can continue. In this way, scientific inquiry may result in chemical discoveries. When researchers are able to develop explanations about experimental evidence, they construct claims or conclusions from the experiments. These claims, supported by experimental evidence, form the basis of scientific arguments that are communicated to other scientists in scientific papers or presentations. The feedback from other scientists is critical to the scientific process. The arguments constructed must stand up to the scrutiny of other researchers in the field (peer reviewers) to be considered trustworthy. The ability to construct valid scientific arguments is a critical skill for anyone in a scientific field. One goal of this course is to help you develop this skill. Constructing scientific arguments

Well-designed experiments generate data that are analyzed to construct conclusions and provide answers to scientific questions. Communicating a sound scientific argument has three components: claim(s), evidence, and reasoning. Scientific arguments revolve around claims or assertions that have been developed as the overarching conclusion of an experiment. Claims are the answer to a scientific question. To support a claim, a written report should present sufficient amount of evidence to indicate that a claim is valid. An experiment may generate a wide variety of data. Not all of it may be relevant or appropriate for answering the original problem or question. Most importantly, the data generated must be analyzed to determine whether it supports the argument. (In some situations, careful analysis reveals how the data refutes a claim.) Finally, a scientific argument should include reasoning, and be accompanied by a persuasive explanation of why the evidence presented supports a claim. You will use these three components to construct an argument in your lab reports.The Figure to the right illustrates how CORE is embedded into a laboratory experiment. Goals for this laboratory session:

1. To make, record, and discuss observations in lab. 2. To use an analogical model to gain insight into how changes in molecular structure affect physical properties of polymers. 3. To visualize chemical structure and interactions in chemical reactions. 4. To design experiments to investigate the properties of polymers. 5. To construct a scientific argument from the designed experiment.

University of Maine General Chemistry Lab (Fall 2021) 5

Pre-lab assignment

Please prepare the following information in your lab notebook. You will not be allowed to work in

the lab without completing the pre-lab assignment before lab starts.

1. Provide a brief (2-3 sentence) introduction to the lab. 2. Create a table of safety information that includes chemicals, the health hazards associated with

them, and the recommended safety handling precautions. This information can be obtained from the safety data sheets (SDS) linked to the chemicals listed in the Procedure section below.

3. Answer each of the pre-lab discussion questions below. Write your answers in your lab notebook – this is to be turned in before you start lab.

a) What role will the paper clips play in this lab? b) What is an analogy? c) How might an analogy help in understanding an abstract concept in chemistry? d) How are the 3 components for a valid scientific argument going to be gathered in this lab?

Laboratory Guide

On the following pages you will find instructions for doing an experiment. In this experiment, you are asked to pair up with another student when doing lab work. If there is an odd number of participants in lab, one group may be permitted to have three people. Your lab work will involve making observations and recording these in your own lab notebook, as well as working in partnership with a lab mate on certain activities such as answering questions, discussing observations, analyzing results, or designing your own procedures in response to scientific questions. As you go through the experimental guide, you will notice there are questions that are set off in the guide (i.e. “Q:”). For example: Q: Are the masses of the polyvinyl alcohol and sodium borate solutions the same? If not, why do you think they are different? You are required to respond to these questions in your lab notebook. Our expectation is that you write enough to give an indication of what you were thinking about. You do not have to write down the question AND answer, but you must address the answer, e.g., “we found that the mass of the 4% polyvinyl alcohol solution was ____g and that of the sodium borate solution ____g. We therefore concluded that the solutions were ….” Part of the purpose of making an entry in your notebook is to allow you to remember later what you were thinking at this point in the experiment, which can be very useful when writing your lab report. It is also evidence for your lab instructor of your thinking process. Please note that you are not required to

provide any particular question and answer in your lab report. However, you may find that some of

the answers would be useful to include in your report. Goggles are required at all times in the lab. There are no exceptions. Gloves and footwear are available. If you have questions about safety, please do not hesitate to ask your laboratory instructor. Materials and equipment:

Chemicals Glassware and supplies

4% Sodium Borate 4 % Polyvinyl alcohol

150 mL beakers, 10mL graduate cylinder, 50 mL graduated cylinders, stirring rod, electronic balance, powder funnel

SAFETY HAZARD NOTE: Although Slime is a nontoxic polymer, keep in mind that contamination may occur from many sources such as the bench top, beakers, weighing spoons, the floor, etc. In addition, some of the chemicals you use to make these polymers are irritants. For example, sodium borate solutions are caustic and should be handled with care. Never ingest anything from a chemistry

laboratory. Wear gloves and always wash your hands at the end of the lab.

University of Maine General Chemistry Lab (Fall 2021) 6

Phase 1: Making observations

The following activities should be completed in the lab.

1. Use clean, dry graduated cylinders, beakers and an electronic balance:

a. Place an empty graduated cylinder on the zeroed balance and record its mass.

b. Measure 30 mL of the 4% polyvinyl alcohol solution into the graduated cylinder and record its mass. Calculate the mass of the polyvinyl alcohol.

c. Using a different graduated cylinder, repeat the procedure in step b to determine the mass of 30mL of the 4% sodium borate solution.

Q: Are the masses of the polyvinyl alcohol and sodium borate solutions the same? If not, why do you think they are different?

2. Now measure 30 mL of water in a newly weighed cylinder and record the mass.

Q: Compare the densities of the sodium borate and polyvinyl alcohol solutions to that of water. Are they different? Why? (Density is equal to the ratio of mass to volume (D = m/V)). Common units in lab for density are grams per mL.

3. Measure 5 mL of sodium borate and 20 mL of polyvinyl alcohol into two graduated cylinders. Pour each solution through a funnel into two separate clean beakers.

Q: What are some of the macroscopic physical properties of the two solutions? Please record your observations when pouring polyvinyl alcohol and sodium borate solutions separately through the funnel.

Q: Were there differences between the solutions when they passed through the funnel?

Q: Make a prediction about what will happen when the two solutions are mixed together.

4. Clean, dry, and record the mass of a third beaker. Pour the 20 mL of polyvinyl alcohol into the massed beaker. Then pour in the 5 mL of sodium borate. Stir.

Q: Record your observations. What happened when the two chemicals are stirred together?

Q: The product you have produced is a new polymer called Slime. What do you think happened when the polyvinyl alcohol and sodium borate solutions were mixed?

Q: Draw a picture (in the box on the next page) of how you imagine the reaction to occur at the molecular level. LABEL the components of your drawing. Don’t worry about being “correct.” Please provide a legible image of your drawing in your lab report.

!"#$%#&'$()*+,-$'"

.'#/'"0

123$'"(4%--'+

University of Maine General Chemistry Lab (Fall 2021) 7

Figure 1. The reaction of polyvinyl alcohol and sodium borate to produce slime

Q: Does Figure 1 explain your observations of the macroscopic (visible) properties of the Slime? Can you think of any limitations of your drawing in explaining your observations?

5. Measure the volume and mass of your Slime and record the values in your lab notebook (include units). Make sure to subtract the mass of your container.

Q: Calculate the density of the Slime (in grams per mL). How does the density of Slime compare to the separate solutions?

6. Pass the Slime through the funnel (it can move slowly).

Q: What happened? Why do you think the Slime moves differently through the funnel than the individual reactants?

After you complete the lab activities above, please go back to the breakout room.

This is the end of Phase 1.

University of Maine General Chemistry Lab (Fall 2021) 8

Phase 2: Exploring the analogy

The following activity should be completed in the breakout room (outside of lab).

General instructions

Each student in your group should fill out the Analog and Target worksheet (page 10) while completing the following activity. You will need to submit a legible copy of the worksheet as part of your

lab report. You will need to scan the worksheet, since your lab report will be electronically submitted. Your team should work together, discussing observations and answers to questions as a way to build a consensus. The analogy is simple and will be familiar to many of you - that is a good thing. The emphasis is on developing skills in the process of constructing meaning from an analogy that will help you gain insight into the chemistry. This is an important part of the scientific process. Partners are encouraged to discuss what they did in lab (phase 1 of the learning cycle) in the context of the activity presented below. For groups wanting extra credit for an extra challenge, see the section at the end of Phase 2.

Pouring Experiment

As discussed before, you will construct and explore an analogy to help you think about the structure, and physical and chemical properties of the polymer, Slime. The analogy uses paper clips to represent the monomer units of the polymer. By linking white paper clips together in a linear chain, you will build a representation of polyvinyl alcohol (even though the chain will be very short compared to an actual polyvinyl alcohol polymer). The cross-linking agent, sodium borate will be represented by black paper clips, which will be used to connect the chains of white paper clips.

1. Create three chains of white paper clips. Each chain should have at least five paper clips in it. Do not connect any of the chains. The chains should be able to move independently of each other.

2. “Pour” one chain through a funnel. Repeat this action a few times to establish what typically occurs.

3. "Pour" single black paper clips through a funnel one at a time. [All of the cross linkers (sodium borate represented by the black clips) are well separated from each other in solution.]

Q: What observable differences are there between pouring the white paper clip chain and single black paper clips? What physical properties of the two different paper clip arrangements are causing the difference?

Q: How does performing this experiment with the paper clips compare to the initial physical properties of polyvinyl alcohol and sodium borate solutions BEFORE they were combined?

4. Take 3 chains of white paper clips and use several black clips to link the chains across from one another (i.e. in a parallel fashion). Do not connect the while chains end to end with the black clips. Now repeat the pouring experiment with the new product you have created.

Q: Does the analogical model allow you to gain insight into why mixing solutions of polyvinyl alcohol and sodium borate solutions creates a new substance with such different physical properties?

The limitations of an analogy

Linking paper clips together to form a chain illustrates a type of connection that is different than a chemical interaction. While many polymers are cross-linked by covalent bonds, in Slime, the borate molecules form weak cross-links to polyvinyl alcohol that are continuously formed and broken in a dynamic equilibrium. This helps to explain why Slime is more of a gel than a hard plastic. The purpose of using an analogy is to help think about some key aspects that an analog shares with the target. While

University of Maine General Chemistry Lab (Fall 2021) 9

the analogy may be helpful, it is also very important to understand what aspects of the target (the cross-linked polymer) are missing from the analogical model (paper clips).

For an illustration of representations of polyvinyl alcohol, sodium borate, and Slime, see http://www.nuffieldfoundation.org/practical-chemistry/pva-polymer-slime (accessed 9/19).

5. Finish filling out the Analog and Target worksheet (pages 10-11) before moving on to Phase 3.

Extra Credit - Extra Challenge

If this analogy seems simplistic to you, consider extending it for extra credit. For example, you might include the effect of solvent interactions, such as dipole-dipole or hydrogen bonding. Other properties to consider are solvent viscosity, the relative size of objects, three-dimensional steric effects, electronic effects, and the relative ease with which links are made and broken. You are not constrained to the provided list.

In order to receive extra credit, describe your modified analogy in your lab report in a separate section called Extra Credit, Extra Challenge. In this section, you should identify how the modified analogy strengthened your understanding or insight of the chemical phenomena under examination. You should also identify explicitly where in the analog-to-target worksheet these modifications revealed themselves. Extra credit will be worth up to 10% on your entire grade for the experiment.

This is the end of Phase 2 (Analog and Target Worksheet is on the next page).

University of Maine General Chemistry Lab (Fall 2021) 10

Analog and Target Worksheet (pages 10-11) Name: _________________________ Fill out this worksheet individually as you perform the analogy activity. Work together to discuss similarities and differences. Each student must include a scanned copy of this sheet with their lab report. Make sure your scan is entirely legible. Please label the components in your drawings.

Analog and Target Comparison

White paper clip chains compared to polyvinyl alcohol

Black paper clips compared to sodium borate

The action of linking white chains with black clips compared to the chemical reaction

The product of linking white chains together with black paper clips compared to the Slime product

Similarities: What characteristics does the analog share with the target?

Differences: What features of the analog (paper clip model) do not represent the target?

Differences: What features of the target are missing from the analog (paper clip model)?

University of Maine General Chemistry Lab (Fall 2021) 11

Analog and Target Worksheet Continued (pages 10-11) Name: _________________________

Draw a representation of each of the following at the molecular level:

Aqueous Solution of polyvinyl alcohol

Aqueous Solution of sodium borate

The chemical reaction that occurs when you stir the solutions together

Slime

University of Maine General Chemistry Lab (Fall 2021) 12

Phase 3: Designing experiments

Plan your experiments in the breakout room before proceeding to lab to complete them.

Using an analogical model to make predictions

Q: How would the physical properties of the already cross-linked chain of paper clips change if more black paper clips (representing the cross-linker sodium borate) were added to connect the chains? Is there a maximum number of black paper clips that can be connected?

Q: The Slime you created in the laboratory earlier was produced by reacting 5 mL of sodium borate with 20 mL of polyvinyl alcohol. How do you think the physical properties of the resulting Slime product would change if you used more than 5 mL of sodium borate but kept the amount of polyvinyl alcohol the same? How would the resulting product be different if you used less than 5 mL of sodium borate but kept the amount of polyvinyl alcohol the same? Justify your response by explaining what differences occur in these two cases at the molecular level.

Draw LABELED pictures to illustrate your explanation and predictions. This will be submitted with your lab report.

Slime created with less than

5 mL sodium borate and 20mL

of polyvinyl alcohol

Slime created with 5 mL

sodium borate and 20 mL of

polyvinyl alcohol

Slime created with more than

5 mL sodium borate and 20 mL

of polyvinyl alcohol

Figure 2. A comparison of slime products at the molecular level with different amounts of reactants

University of Maine General Chemistry Lab (Fall 2021) 13

The experiment

Your team should design an experiment to answer the scientific question below:

Scientific Question: How do different proportions of the two reactants, polyvinyl alcohol and sodium borate affect the material properties of the new polymer that is formed?

Throughout this process, try to think about how changes at the submicroscopic level (in the arrangement and interaction of molecules) affect the macroscopic (visible to you) properties of the new material that is produced (the slime polymer).

Think carefully about how you will evaluate each sample of Slime you create with different ratios of reactants. In addition to recording qualitative observations (e.g. visible consistency, funnel flow patterns) we encourage you to design experiments to make quantitative measurements, for example:

• density • mass of excess reagent • flow rate • degree of “squishiness”

The goal is to generate data that can be used to answer the scientific question.

Before going into lab, use the Designing Experiments worksheet (page 14) to outline your procedure and have your laboratory instructor check and initial it. Fill out this worksheet as a group as you go through your experiment. Taking detailed notes may help you in writing your lab report. This worksheet is to be scanned and submitted as part of your lab report. Please make sure that the canned copy is entirely legible! (You may lose points it your scans are hard to read.)

Clean-up

When you are finished with your experiment, PLACE ALL EXCESS and USED CHEMICALS IN THE PROPERLY MARKED WASTE CONTAINERS. Wash glassware and return it to your drawer. Wipe benches clean of spills with a paper towel.

Reflections & post-lab discussion (group discussion)

To be completed at the very end of the laboratory session

1. What kinds of patterns do you notice in the data you collected? What claims can you make?

2. How can you use the analogical model to explain your results at the molecular level to someone unfamiliar with the chemistry in this lab?

3. How did the analogical model help explain the chemistry?

Before you leave, have your laboratory instructor sign your laboratory notes and turn in the yellow

copies from your notebook.

University of Maine General Chemistry Lab (Fall 2021) 14

Designing Experiments Worksheet Names: Experiment #: Signatures: Section:

Scientific Question: How do different proportions of the two reactants, polyvinyl alcohol and sodium borate affect the material properties of the new polymer that is formed? Please use this sheet to summarize your lab group’s experiments and findings. Before going into lab, have your lab instructor check and initial it. This worksheet is to be submitted as part of your lab report. Make sure that when scanned, it is entirely legible!

Please describe your proposed experiment. Any predictions? (Check in with your lab instructor before performing experiments) Instructor’s initials:________

(attach extra pages if needed)

Describe the data collected and any changes in procedures. What patterns have emerged?

(attach extra pages if needed)

What claims can you make?

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Rubric for laboratory reports (due next lab meeting) (Use the Gen Chem lab report template)

Due next time your lab meets = draft lab report. DO NOT SUBMIT THE DRAFT.

Introduction: (10 pts)

This section provides a short introduction or summary to the report, and should include: • Title of the report • Author name (your name) • Lab partner name (if you had partner(s)) • Date of experiment • Overview: a few sentences describing what the lab experiment was about We also recommend including your section and TA name (optional)

Data, Results, Evidence: Submission of the Analog and Target and Designing Experiments Worksheets are required. (25 pts total)

This section organizes data, results, and evidence. The goal of the section is to describe what you did and what data were collected. Observations can be important data to use in analysis. See additional instructions in the Template for Submission of Lab Reports (in ICN Resources).

This section should include: • Figure 1. Include the drawing requested in phase 1. • Figure 2. Include the drawing requested from phase 3 • Procedure: Reference the laboratory procedure that was downloaded and the date it was

accessed (Polymers and Cross Linking, InterChemNet, accessed: 10/1/2019). Any changes in procedure should be noted.

• Analog and Target (A&T) Worksheet: This worksheet should be included. • Designing Experiments (DE) Worksheet: this worksheet should be included. • Observations: include observations and note if they help explain any chemistry • Note: since patterns are often critical to understanding data, present data in Tables as

well as Figures. This will increase the quality of this section. Data from outside sources can be used in this section to support data obtained.

Analysis of Evidence (Reasoning): Scientific explanations that use evidence and appropriate chemistry concepts to construct claims. (30 pts total)

In this section, your data, results, and evidence, including observations, are analyzed to help explain the chemistry that occurs in the experiment. Your analysis will be a major support for any claims you make. See additional instructions in the Template for Submission of Lab Reports (in ICN Resources).

This section should carefully analyze evidence (using reasoning) and include: • Data to analysis connection: a goal of this section is to connect data, results, and

evidence to your analysis. This is in preparation for making a claim. • Include answer to scientific question #1: How do different proportions of the two

reactants, polyvinyl alcohol and sodium borate affect the material properties of the new polymer that is formed?

• Discuss A&T Worksheet: discuss how the analogy relates to your experimental data. Try connecting it to the analogical model to develop your explanations of results and underlying chemical concepts in your discussion

• Discussion of phenomena: you can discuss phenomena at both the submicroscopic (molecular) level & macroscopic (visible to your eyes) level in order to explain the chemistry of this experiment.

• Discuss DE Worksheet: discuss the rationale behind your experimental design. • Discuss Observations: include observations and note if they help explain any chemistry

Data from outside sources can be used in this section to support analysis. Claims(s): Statement(s), derived from evidence, using scientific reasoning (15 pts total)

This section is to present claims. It is advantageous to directly connect evidence (from your lab investigation and outside sources) that you utilize in your discussion to develop your claims. See additional instructions in the Template for Submission of Lab Reports (in ICN Resources). Addressing the scientific question as part of your claim may be useful.

University of Maine General Chemistry Lab (Fall 2021) 16

Avargil, S., Bruce, M., Amar, F., & Bruce, A. (2015). Students’ understanding of analogy after a

core (chemical observations, representations, experimentation) learning cycle, general chemistry experiment. Journal of Chemical Education 92, 1626-1638. doi:DOI: 10.1021/acs.jchemed.5b00230

Bruce, M., & Bruce, A. (2016-2020). Fostering connections between macroscopic, submicroscopic, and representational levels using analogical reasoning in the chemistry laboratory. In. University of Maine: National Science Foundation.

Bruce, M. R. M., Bruce, A. E., Avargil, S., Amar, F. G., Wemyss, T. M., & Flood, V. J. (2016). Polymers and cross-linking: A core experiment to help students think on the submicroscopic level. Journal of Chemical Education(93), 1599. doi:10.1021/acs.jchemed.6b00010

President's Council of Advisors on Science and Technology. (2012). Engage to excel: Producing one million additional college graduates with degrees in science, technology, engineering, and mathematics. Retrieved from www.whitehouse.gov/ostp/pcast