Crystal Growth Part 2 (In Person)

Edit Experiment

VIDEO LINKS:

Lab experiments (Write protocols and perform experiments based on these):

  1. Growing Large Single Crystals
  2. Crystal Maintenance

Data analysis and interpretation (Use these if you need help with your data and discussion)

  1. Crystallization

The prelab must include Experimental Protocol, Chemical Table and Equipment Table.

The lab report requires all sections (including prelab sections) to be completed in one document.

Experimental Protocol

(Analysis) Watch the experiment videos.  Take notes on the protocol.  Stop the video and re-watch as necessary to acquire the details of the procedure.  Write out the protocol for each part of the experiment.  (It can be written in sequential steps.  Complete sentences are not necessary.)  This is the protocol you will follow, so be detailed.

Chemical Table

(Representation) Prepare your chemical table including the materials you will use in the experiment.  Here is a general template that you may use.
Chemical Name Chemical Formula Molar Mass (g/mol) Hazards Reference PPE
Sodium Chloride NaCl 58.5 Skin irritation https://fscimage.fishersci.com/msds/21105.htm  
           
           
           

Equipment Table

(Analysis) Identify the equipment (type AND size) needed for the experiment and include the name and an image of each.  Be sure to describe the equipment, how to use it, and why it is suitable for this use.
Equipment Name Equipment Picture Intended Purpose

Data Collection

(Acquiring competencies) Following your detailed protocol based on the videos, perform all the experiments. Record your observations and take pictures of your key steps in the process.  Your observations and images need to be incorporated in your data section and this section should be as detailed as possible as you will use this information to complete your discussion.

Data Processing

  1. (Assumptions and Analysis) Fill in the following table using the observations and data from your experiments.
Assumptions made Testing the assumption If assumptions are wrong ...
Our alum grow solution is saturated. Submerge the crystal in the grow solution. If it is unsaturated, the crystal will disappear. If it is very supersaturated there will be other alum crystals forming.
The string will not dissolve in the solution. Submerge the string in the grow solution.

Discussion

Write a minimum one-page (12 font, single spaced) discussion on the experiment conducted this week. Address at least one question in each category as fully as possible integrating the collected data, providing explanations for the observed trends and evaluating whether your original assumptions about the experiment were validated by the results. The assignment will be graded on completeness, clarity of the explanations and the meaningful integration of the collected and calculated data. Correct grammar and appropriate format for the chemical formulae and chemical reactions is expected. You may use the outline included at the end of this document on how to build your essay to address each category.  
  1. (Existing knowledge, research, and views) Describe the difference between saturated and supersaturated solutions.
  2. (Existing knowledge, research and views) Classify alum as an ionic or molecular compound and describe the crystal structure of alum.
  3. (Lab skill) Describe the process involved in starting the crystal growth project and provide a purpose for each step.
  4. (Analysis) Describe what characteristics of the seed crystals you considered when selecting the most suitable crystals for this project. Provide at least one supported argument to justify your selection process.
  5. (Lab skill) Estimate the approximate size of a seed crystal that would be useful to grow a large single crystal from.
  6. (Analysis) Provide at least one supported argument for using a saturated solution to grow the single crystal from the seed crystal.
  7. (Assumptions) A seed crystal is submerged in a solution and disappears. What assumption can we make about the solution?
  8. (Analysis) Describe what happens with the saturated alum solution that causes the growth of the single crystals from the seed crystals.
  9. (Analysis) Provide at least two supported arguments for starting the crystal project with two seed crystals submerged in the grow solution.
  10. (Analysis) Your seed crystal should be suspended by a thread in the grow solution, instead of remaining in the Petri dish. Provide a supported argument for why this transition is necessary.
  11. (Lab skill) Describe the process of monitoring and maintaining the large single crystal.
  12. (Assumptions) Each time the alum single crystal is maintained, it needs to be rinsed thoroughly with distilled water before being placed into the filtered grow solution. What assumption are we making about the crystal that makes this approach necessary?
  13. (Analysis) Alum is soluble in water. Why doesn’t the crystal dissolve when it is washed with water.