CHEM 1412 OL Exp2. Crystal Growth - Sp23122222222222

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Lone Star College, CyFair *

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1412

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Chemistry

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Feb 20, 2024

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Experiment #2: Crystal Growth Lab Required reading: N. Tro, 11th Edition, Chapters 3 and 11. § 3.2 – Chemical Bonds § 3.5 – Ionic Compounds: Formulas and Names § 13.4 – Types Crystalline Solids § 13. 5 – Structures of Ionic Solids Learning Goals: § To practice nomenclature of simple ionic compounds § To observe how a crystal grows. § To see the physical relationship between a physical crystal and a crystal structure. Background information and theory: In this lab you will be able to observe how a crystal grows and to see the physical relationship between a physical crystal and a crystal structure. The required reading from your textbook will provide background information. You will reach some those pages at the end of the semester. It can take several months to grow crystals but in this lab we will do a quick method to grow borax crystals. In the following video you will learn about unit cells in crystals: https://www.youtube.com/watch?v=KNgRBqj9FS8 The following YouTube sites provide further background: DIY Crystal at Home (2) - Copper(II) Sulfate https://www.youtube.com/watch?v=k3nClG-DT7w How to grow beautiful crystals of salt - do your chemical experiment! https://www.youtube.com/watch?v=FKCS1DvORug How To Make Your Own Salt Blue Crystal - Amazing Science Experiments with Home Science https://www.youtube.com/watch?v=yEcIUxqRn5g Materials : Borax Warm water String 2 pencils Pipe cleaners Large bowl Scissors 2 identical jars Cooking pot Tablespoon

SDS on chemicals: Borax (sodium tetraborate decahydrate) is harmful if swallowed, causes skin and eye irritation. Avoid inhaling the compound as it may cause membrane irritation. Handle with gloves. NOTE: This experiment has an at home activity that requires at least 3 days to be completed (the crystal needs time to grow). I suggest starting this experiment in advance and let the crystal grow until next week. If you try to do this overnight your crystals will be small, and your grade will reflect the size and quality of your crystal. Borax can be found in any supermarket or pharmacy in the detergents/laundry area (the most famous is the 20 mule brand, this is their website: https://www.20muleteamlaundry.com/ ) Important remarks: Regarding the materials and procedures for this crystal lab, you must know the following information: * Borax and boric acid are NOT the same, as you can see in the link below, borax is used as a detergent, as long as it is not ingested, or the dust is inhaled, this material is safe. It is suggested to avoid contact with the skin by using gloves while handling the product. You are expected to use cation and wear goggles and some lab coat or apron to do any of these experiments, for example, when adding the solid to the boiling water, make sure you add it slowly, also, try to use a well ventilated area to prepare the solution, if possible, turn on the extractor/fume hood in your kitchen. https://www.20muleteamlaundry.com/compare/borax-vs-boric-acid/ ** Please see safety information about borax in this link: https://www.20muleteamlaundry.com/safety-information/ ***This experiment is actually based on a DIY activity from the website for the product, some instructions may not be very specific, if you have questions about the procedure or if it is not clear to you, please ask https://www.20muleteamlaundry.com/uses/arts- crafts/crystals-for-diy-home-crafts/ **** If after going through this information you still feel this is not safe to do at home or if you don't have the required materials, then we have some alternatives including: • A similar procedure can be used with sugar or with salt. The advantage of the borax is that the crystals form really fast compared with sugar of salt crystals that might take more than 3 days to form. You will have to use a lot of the solid (sugar or salt) to saturate the solution. • Although the list of materials was sent to students at the beginning of the semester, we do understand that not all students will have all the materials available or might not feel comfortable completing one of these at home activities. In the event a student is in this situation, talk to your instructor about any policy that allows students to drop lab reports at the end of the semester if they were not able to complete a specific lab. Procedure: Part 1

1) Watch the following video: https://www.youtube.com/watch?v=FFR4nei9qv8 2) Collect the information from the video in the data pages. Part 2: AT HOME 1) All experiments at home must be done carefully. 2) Avoid touching hot substances to prevent injuries due to physical burn. 3) Use goggles at all times to avoid eye injury. 4) You may use gloves if available. 5) If you get a reagent in your skin or eyes flush for at least 15 minutes with running water. 6) Keep your experiment away from people not doing the experiment. 7) Do not leave your experiment unsupervised. 8) Do not ingest any of the chemicals used. 9) *Label your substances 10) *Clean up quickly once you finish your experiment. 11) *If using anything from your kitchen, be sure to thoroughly wash and dry before next use. This procedure was adapted from https://www.20muleteamlaundry.com/uses/arts-crafts/crystals- for-diy-home-crafts/ How to Create Crystals with Borax 1. Create shapes • Use the pipe cleaners to create the foundation of your crystals for the experiment. Take the pipe cleaners and mold them into whatever shape you want the crystals to turn out as, these will form the basis for your creation. • Be sure to select the color of your pipe cleaners purposefully. Because Borax crystals is white, the crystals will form clear, so the pipe cleaners underneath will give them their color. To make your own colorful creations, be sure to pick the brightest colors for your pipe cleaners! 2. Boil water • Take your pot and bring the water back up to boiling point. This is where you’ll dissolve your Borax mixture. • It’s up to you how much water to use, but 3 cups should contain enough Borax to complete the experiment. Feel free to add more if need be. 3. Mix solution • Add the borax carefully. Add about 3-4 Tbsp of Borax for every cup of water in your solution.

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• Stir until the Borax dissolves in the water. You want the water to be clear because if the water gets cloudy then your crystals will be cloudy. 4. Pour into jars • Once your solution is mixed, pour into the mason jars about three quarters of the way to the top. 5. Suspend pipe cleaners • Use the string to tie your pipe cleaners to the pencils. Then place these pencils over the rim of each jar so that the pipe cleaners are suspended in the water. Be sure to thoroughly wash and dry hands. 6. Leave overnight • The submerged pipe cleaners should form crystals over the next 12-24 hours. The longer that you leave them then the bigger they will grow. Be sure that none of the pipe cleaners are touching each other or the sides of the jars so that they can grow as large as possible. 7. Remove and dry crystals • The crystals should have grown around the colored pipe. Now, simply take them out of the jars and let them dry and marvel in your crystal creations! 8. Share your results • Now that you know how to make your own crystals, take a picture of your crystal and add it to your report. Write a paragraph explaining your observations and comments about this experiment (data section).

Name: ____________________________________ Data Sheet Collect the following information from the video and complete the calculations indicated below. 1) According to the video, is the initial water used cold or hot? Why do you think the temperature of the water is relevant? (Hint: What happens with the solubility of the salt when the temperature of the water changes?) The Initial water was hot, when heated, it was used to create the salt crystallization. 2) According to the video, the first solution is filtered. Why? To filter out the solid impurities in the solution 3) According to the video, what can happen if the beaker is not covered with foil? Dust can make its way into the solution. 4) According to the video, how long does it take for the crystal growth process to occur? (minutes, hours, etc.) It takes 24 hours long for the crystal to occur. 5) Observe the final crystal in the video. How would you describe the physical properties of the crystal? -Blue colored -solid -exothermic 6) A seed of CuSO 4 .5H 2 O with a mass of 0.500 g was carefully placed into a saturated solution of copper (II) sulfate. After 7 days the mass of the seed crystal was determined to be 0.648 g. After 14 days the mass of the crystal increased to 0.899 g and after 21 days the mass of the crystal was found to be 1.081 g. Make a

plot of mass vs time (days) and extrapolate to predict what would be the mass of the crystal in 28 days if the growth is linear. Include labels and units on each axis. 1) AT HOME: Write your observations and comments about the crystal growth you did at home. Green pipe cleaner: The crystal grew tremendously overnight on day one, it crystallized the shape of the pipe cleaner to the sides of the container. On day 2 the crystallization began to slow down there were no major changes of growth. On day 3, the crystallization ins growing little by little. On the last day the crystal became a little dense, but you were still able to see through it. As a result of the growth, the crystal grew about 0.3 millimeter. The physical properties of the crystal were clear, hints of white. And a bit cloudy and it was a solid Blue pipe cleaner: This was almost the exact same as the green pipe which is rapid growth first day. The only difference is the shape this one is smaller than the green pipe cleaner, making it tightly compacted, and even surpass the size of the green pipe cleaner. On day 2 the growth started to slow down and began to grow and a constant rate. On day 3 there was no change in the rate. On the last day the crystal became a little dense, still being able to see through it. As a result, the crystal grew about 0.4 millimeter. The physical properties of the crystal are clear, hints of white, a bit cloudy and it is a solid. 0 0.2 0.4 0.6 0.8 1 1.2 0 5 10 15 20 25 Time mass

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2) Add a picture of your crystal here.

Name: ____________________________________ Post-lab: Crystal Growth Your instructor may ask you to answer these in your lab notebook, or to answer directly on this page and turn it in, or to include these answers in a formal lab report. Follow your instructor’s directions. Using the following data answer the questions below. Pay special attention to significant digits. Data table Crystal growth Mass of the initial seed 0.825 grams Concentration of the copper(II) sulfate solution 0.100 M Volume of copper(II) sulfate solution used 96.50 mL Mass of the final crystal 3.176 grams 1) How many grams of solute from the solution was incorporated to your original seed? (final crystal mass-initial crystal mass) 2.351 g 2) How many moles of solute from the solution were incorporated to the original seed? (Use the molar mass of the copper (II) sulfate pentahydrate to transform the grams found in question 1) 000941605 g 3) How many moles of copper (II) sulfate were available in the solution? (You need to calculate the moles of solute present in the initial solution by using the initial volume and concentration (moles = M x V)) (Show all your work) 0.100 x 96.50 = 9.65 moles 4) What percentage of the copper sulfate from the solution was incorporated into the seed? (What is the % recovery from the solution?). Show all your work. % recovery= (Moles incorporated/moles available)x100% 96.50/9.65 x 100% = 10%