100 PIONTS PLZ HELP POLYER LAB
Chemistry 30
Lab Notebook and Lab Report
materials required are bolded (component of the lab, you must carry out the pre lab procedure to determine the bounce and/or stretch of the silly putty.
1. Use a graduated cylinder (or teaspoon)* to add 10 mL of tap water to a Dixie Cup. With a pen, mark the level of the water on the outside of the cup. Add an additional 10 mL of water to the cup and mark the water level. Repeat 2 times until a total of 40 mL has been added to the cup. Now dump out all the water. These marks will be used to measure out the proper amounts of other ingredients.
2. Measure 10 mL of tap water into the Dixie cup and add 3-4 drops of food coloring.
3. Using the markings on the Dixie cup, add ~10 mL of Elmer’s white glue directly to the cup and mix (stir rod
or spoon) gently until the mixture has a uniform consistency.
4. Use a graduated cylinder (or 1⁄2 cup measuring cup) to measure 125mL of tap water in a beaker (larger plastic
container). Using an electronic balance, weigh boat (or wax paper) and a scoopula (or teaspoon), add 8.7 grams of Borax to the water. This is your saturated (6.5%) sodium tetraborate solution. Stir the solution until all of the solid is dissolved.
5. To the diluted Elmer’s glue solution in the dixie cup, add 10 mL of the saturated sodium tetraborate solution and stir immediately and continuously!
6. Remove putty from Dixie cup (leaving any excess water in the cup) and knead the putty on a paper plate until the desired consistency is reached (think silly putty consistency).
7. Test this polymer using the bounce test and the stretch tests that are described below (this will be your baseline data to see if your designed polymer improves).
*a teaspoon holds approximately 5mL of liquid.
Record all of your questions, observations about the reactants, procedure and products in a lab notebook. Hypothesis
Based on your learning in the pre-lab section, create a hypothesis that predicts the changes in the physical properties of the polymer based on procedural changes you are going to make in the design challenge. Be sure to follow “If...then...because...” format.
Design Challenge (Procedure)
Redesign or modify the procedure you used above to make a material that is either elastic (stretchy) or rigid (bouncy). Experiment with different ratios of poly(vinyl alcohol) & saturated sodium tetraborate (borax) solution to make putty that can bounce OR stretch the best. You will need to carry out at least two distinct procedures.
Option 1: Create a polymer with the highest bounce
To test the “bounciness” of your polymer, we will use a meter stick. You will drop (not throw) the putty from 30cm height and see how high it bounces. Complete three separate bounce tests and find the average height.
Option 2: Create a polymer with the longest stretch
To test the “stretchiness” of your polymer, we will use a meter stick as well. For the test, hold one end of the putty and allow gravity to stretch the material. Measure the length of the putty before it breaks. Complete three separate stretch tests and find the average length.
Observations
In this section, you need to include two things:
1. A qualitative description of your final polymer
2. A graph that shows the stretch/test results throughout your design process. (I would recommend using
Microsoft Excel for this graph). This can be any type of graph you think would represent this data the best.
Discussion Questions
1. How does the addition of sodium borate change the physical properties of the poly(vinyl alcohol) solution? Explain using what you know about chemical bonding.
2. Below you can see the reaction mechanism for the cross-linking reaction. What type of organic reaction is present in step 5?
3. In your own words, explain what a polymer is.
4. Give an example of a commercial product that is made from a polymer. Explain how the underlying
intermolecular and intramolecular structure of the selected polymer meet the needs of the purpose of the
product.
5. What measures could you have taken to improve your design further? Explain how these changes would
have helped make the putty more stretchy/bouncy.
Conclusion
Write a paragraph the outlines your findings and directly relates back to your hypothesis. In addition, discuss how the concepts/skills applied in this lab are applicable outside of the classroom. If applicable, you should also compare you results to those of one or more classmates (also explain the differences you observed).
Sources of Error
List two possible sources of error in this experiment (ensure they are not human error) and describe how they could have affected your results. Explain a procedural fix for each of your sources.