Homemade Christmas tree

For those who want to feel the spir­it of Christ­mas ev­ery day!

Safe­ty pre­cau­tions

Per­form this ex­per­i­ment only un­der adult su­per­vi­sion.

Equip­ment

• 3 tsp ta­ble salt;
• 3 tsp yel­low prus­si­ate of potash so­lu­tion;
• liq­uid soap;
• boil­ing wa­ter;
• glass;
• pa­per Christ­mas tree;
• Petri dish or saucer.

Step-by-step in­struc­tions

Pour 3 tsp of ta­ble salt into a glass. Add 3 tsp 0.3M so­lu­tion of yel­low prus­si­ate of potash. Add some boil­ing wa­ter. Stir. Pour the re­sult­ing mix­ture into a Petri dish or saucer and add a few drops of liq­uid soap. Place a pa­per Christ­mas tree in the cen­ter of the con­tain­er. It’s im­por­tant that the pa­per be of the right con­sis­ten­cy to ab­sorb wa­ter well with­out de­form­ing. Wait 12 hours. Do not move or jos­tle the Christ­mas tree while the crys­tals are grow­ing. Af­ter 12 hours, the Christ­mas tree will be cov­ered in "snow!”

Process de­scrip­tion

The hot so­lu­tion we poured into the Petri dish con­tains a lot of dis­solved sodi­um chlo­ride NaCl. Ac­tu­al­ly, it con­tains a greater quan­ti­ty of salt than room-tem­per­a­ture wa­ter can hold. Con­se­quent­ly, when the sys­tem cools, the sodi­um chlo­ride pre­cip­i­tates out of the so­lu­tion in the form of tiny, fluffy crys­tals. These crys­tals ap­pear on the tree thanks to the cap­il­lary ef­fect. First, the so­lu­tion soaks through prac­ti­cal­ly the en­tire­ty of the pa­per tree. Then, as the wa­ter grad­u­al­ly evap­o­rates from the sur­face of the pa­per, the salt grad­u­al­ly set­tles on it. But how did we ob­tain such fluffy salt crys­tals? Salt crys­tals are usu­al­ly cu­bic, right? This is most­ly due to the ad­di­tion of potas­si­um hex­a­cyano­fer­rate and the way the crys­tals form on the pa­per tree. A sim­i­lar ex­per­i­ment is in­clud­ed in the “Chem­istry of Christ­mas” set from the MEL Chem­istry sub­scrip­tion.