How to Grow a Large, Single Crystal: Part 1 (Growing a Seed Crystal)

Summary

This video tutorial from the University at Buffalo introduces the first part of a two-part series on growing large single crystals. The focus is on creating a seed crystal using aluminum potassium sulfate dodecahydrate, dissolving it in distilled water, and allowing it to crystallize through slow evaporation. The process involves heating, stirring, and carefully transferring the solution to a wide dish for optimal crystal growth. Protective equipment is emphasized, and tips on dealing with impurities and harvesting seed crystals are provided, setting the stage for the next video on transforming these seeds into larger crystals.

Takeaways

• 🌱 The video series is about growing a large single crystal, starting with the creation of a seed crystal.
• 🔍 The process involves slow evaporation of a solution to allow crystal nucleation and growth, influenced by local conditions like humidity and room temperature.
• 🧪 The crystallization material used in the demonstration is aluminum potassium sulfate dodecahydrate, which is dissolved in water.
• 💧 Distilled water is recommended over tap water to avoid interference from minerals and ions.
• 🔥 A Pyrex glass beaker and a hot plate are used to dissolve the alum, with a stir plate and magnetic stir bar to ensure even dissolution.
• 🥽 Safety precautions include wearing eye protection to prevent splashes, though gloves are not necessary for handling alum.
• 👀 The solution should be heated to about 45 to 55 degrees Celsius without boiling to dissolve the alum completely.
• 📏 The amount of water used can affect the rate of crystal growth; more water means slower growth, which is preferable for large crystals.
• 🛠️ A wide, flat dish is used for crystal growth to provide more space for crystals to grow without interference.
• 🕰️ The process requires patience as it involves waiting for the crystals to grow, which can be accelerated by reducing the amount of water.
• 🔬 If the solution remains cloudy after heating, it may be due to impurities in the alum, which will settle over time, allowing for a clear solution to be decanted for crystal growth.
• 🌟 Seed crystals are harvested when they are large enough without bumping into each other, using tweezers and a squirt bottle to prevent damage.

Q & A

What is the main topic of the two-part video series?

The main topic of the video series is how to grow a large single crystal.

What is the first step in growing a large single crystal according to the video?

The first step is to grow a nice seed crystal.

What is the crystallization material used in the U.S. Crystal Growing Competition mentioned in the video?

The crystallization material used is aluminum potassium sulfate dodecahydrate.

Why is it important to keep a constant temperature during the crystal growth process?

Maintaining a constant temperature is important for the controlled evaporation of water, which allows the crystals to nucleate and grow at a steady rate.

What factors affect the rate of water evaporation during the crystal growth process?

The rate of water evaporation depends on local conditions such as room humidity and temperature.

Why is distilled water preferred over tap water for the crystal growing solution?

Distilled water is preferred because it lacks the minerals and ions found in tap water that could potentially interfere with the crystal solution.

What type of container is recommended for heating the solution in the video?

A Pyrex glass beaker is recommended because it can be heated without the risk of cracking.

What safety precautions should be taken while preparing the crystal growing solution?

Wearing eye protection is advised to prevent any potential splashing of the solution.

Why should the solution not be boiled according to the video?

Boiling is not necessary as the powder should dissolve at about 45 to 55 degrees Celsius, and boiling could introduce impurities.

What should be done if the solution appears cloudy after heating?

If the solution is cloudy but no solids are visible, it indicates impurities in the alum. The solution should be left undisturbed for about 24 hours to allow the impurities to settle.

How should the seed crystals be harvested for the next part of the experiment?

Seed crystals should be harvested using tweezers and a squirt bottle to prevent the formation of crusty deposits. Only individual crystals with flat surfaces and sharp edges should be selected.

What is the purpose of the seed crystals in the crystal growing process?

The seed crystals serve as a starting point for the growth of larger single crystals in the next step of the experiment.

What is the significance of the size of the seed crystal in the final outcome of the crystal growth?

The larger the seed crystal, the better the chances of growing a large single crystal in the subsequent steps of the experiment.