Easily create beautiful needle-like crystals in solution
At ChemTalk, we were so amazed by the ease and beauty of producing elemental tin crystals, we just had to share it with everyone. This is guaranteed to ignite the passion of chemistry in anyone who watches these crystals grow.
Tin Crystal Procedure
Combine 12 grams of tin (II) chloride, 6 grams of sodium bisulfate, and 125 grams of distilled water. Mix the solution until everything dissolves – it will be very cloudy. Filter the solution through a coffee filter to remove some of the particulates.
Then, add zinc metal and watch! We hung a 5g rectangular-shaped pure zinc anode on a string. Zinc anodes are commonly used in electrochemical cells. Tin crystals were growing within seconds, and within 2 hours our 125ml Erlenmeyer flask was filled with crystals.
Tin is below zinc in the activity series of metals, and zinc will easily reduce tin (II) to elemental tin via a single displacement oxidation-reduction reaction. You can check standard reduction potentials to see which metals will displace others. The sodium bisulfate helps to maintain a slightly acidic environment. The latin name for tin is stannum, so the atomic symbol for tin is Sn.
Reaction between tin and zinc:
SnCl2 + Zn -> ZnCl2 + Sn (s)
Tin Crystals – our results
The first time we ran the experiment, after 24 hours the tin floated to the surface and coalesced into a mossy state. We called this tin “mossy tin”. We were able to drain the solution and pull the pure tin out of the solution.
In the second run, the crystals have remained in solution for a week, allowing us to admire them each day. Most of them remained in a beautiful needle-like silvery metallic state, as you can see in the title photo.
Making crystals of other elements
Silver and lead will also form crystals in solution, but silver is expensive and lead compounds are toxic. This made tin crystals the most accessible home science demonstration in the metal-crystal-growing genre that the ChemTalk team is aware of. If you want to go the electric route, you can do electrolysis of a tin chloride solution which will also generate crystals.
Leave your favorite experiments in the comments below! Or try some forensic science (from Susan Koch’s blog)