Growing Crystals of Rochelle Salt
VIDEO LINKS:
Consider before watching the videos:
How would you grow a large crystal?Lab Experiments (Write protocols based on the videos then complete your protocols as you perform experiments in class):
Data analysis and calculations (Use these if you need help with your data and calculations)
The prelab is due before your lab class meets and must include Experimental Protocol, Chemical Table and Equipment Table.
Experimental Protocol
(Analysis) Watch the experiment videos. Take notes on the protocols. Stop the videos and re-watch as necessary to acquire 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 follow, so be detailed.
Chemical Table
(Representation) Prepare your chemical table including the materials you 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 (picture) of each. Be sure to describe the equipment, how to use it, and why it is suitable for this use.
| Equipment Name | Equipment Picture or Description | Intended Purpose |
Data Collection
(Acquiring competencies) Following your detailed protocol, 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
- (Existing knowledge, research, and views) Describe the difference between saturated and supersaturated solutions.
- (Existing knowledge, research and views) Classify the Rochelle salt as an ionic or molecular compound.
- (Lab skill) Describe the process involved in growing a crystal and provide a purpose for each step.
- (Representation) Write the balanced chemical equation for the dissolution of Rochelle salt in water.
- (Interpretation) Describe the meaning of the previously written equation on the macroscopic and microscopic scale.
- (Representation) Write the balanced chemical equation for the Rochelle salt crystal formation.
- (Interpretation) Describe the meaning of the previously written equation on the macroscopic and microscopic scale.
- (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.
- (Analysis) Provide at least one supported argument for using a saturated solution to grow the single crystal from the seed crystal.
- (Assumptions) Describe at least one characteristic that would have to be true about a solution that dissolves a seed crystal.
- (Analysis) Describe what happens with the saturated solution that causes the growth of the single crystals from seed crystals.
- (Analysis) Provide at least two supported arguments for starting the crystal project with two seed crystals submerged in the grow solution.
- (Analysis) Comment on why the Rochelle salt crystal doesn’t dissolve in water when washed.
- (Analysis) Identify at least one of the 12 principles of green chemistry applied in this experiment. Justify your selection. 12 Principles of Green Chemistry
- (Assumptions) Fill in the following table using observations and data from your experiments.
| Assumptions made | Testing the assumption | If assumptions are wrong ... |
| Single crystals of Rochelle salt can be grown | ||
Summary
The summary has two parts: an abstract and an experimental protocol reflecting the experiment that you actually performed. The abstract and experimental protocol should both be between 100-250 words, size 12 Arial font each. There may be multiple experimental protocols for one experiment.Part 1.
Title of Experiment: Performed tasks and applied techniques to accomplish the goal of the experiment and a description of the system under study (the title you are given for the lab is insufficient). Ex. Growing Single Crystals of Rochelle Salt from a seed crystal in Saturated Solution at Room TemperatureAbstract
(This is a highlight of what you learned from performing the experiment and processing your collected data. Below is a template and an example of what you are expected to write.)
In this lab experiment we investigated [purpose of your experiment] using [list the materials you worked with] and we found that [present the highlights of your results (include numbers)]. The results [present significant results]. The collected data compares to [draw conclusion about your results compared to other sources (this could be another group or the literature value)]. The [add type of measurement individually] measurement was collected using [describe instrument by sensitivity].
Think through this before writing:
- Purpose: What were you trying to do?
- Materials used: What chemicals and materials did you work with?
- Method: What instruments were used to collect measurements and how were the measurements collected?
- Results: What did you find out about the objects under study?
- Significance: What did you learn about the precision and accuracy of your techniques? How do your determined values compare to reported values?