Top 5 Halloween Science Experiments

How to make really spooky Halloween decorations

Hal­loween is com­ing… and if your cos­tume is ready, it’s the per­fect time to think about your dec­o­ra­tions – how to make your cel­e­bra­tion un­for­get­table. Here are 5 sim­ple ex­per­i­ments that will help make your Hal­loween tru­ly creepy!

Foam Jack-O’-Lantern

To make foam­ing pump­kin, you’ll need:

  • hy­dro­gen per­ox­ide, H₂O₂ (any strength will do, but the less con­cen­trat­ed it is, the less dense your foam will be) (1/4 cup or 60 mL);
  • wa­ter (1/8 cup or 30 mL);
  • yeast (1/2 oz or 14 g);
  • any food col­or­ing (1 tsp or 5 mL);
  • liq­uid dish soap (1 Tbsp or 15 mL);
  • 3 cups or small bowls;
  • jack-o’-lantern (you won’t need can­dles, but keep the top – it will serve as a lid).

What’s next?

  1. In the first cup, mix the hy­dro­gen per­ox­ide, liq­uid soap, and food col­or­ing;
  2. In the sec­ond cup, mix the yeast with some wa­ter;
  3. Put the emp­ty third cup into the pump­kin and pour in the con­tents of the oth­er two cups: first the soap so­lu­tion, then the yeast mix­ture;
  4. Quick­ly put the lid on the pump­kin: this re­ac­tion will pro­duce a lot of foam.

When hy­dro­gen per­ox­ide de­com­pos­es, it pro­duces oxy­gen and wa­ter. Nor­mal­ly this is a rel­a­tive­ly slow process, but yeast speeds it up dra­mat­i­cal­ly. The rapid­ly-gen­er­at­ed oxy­gen whips the liq­uid soap into a thick, vo­lu­mi­nous foam. There’s so much foam that it forces its way out of the jack-o’-lantern!

Jack-O’-Lantern in Green Flame

To make a pump­kin bathed in flame, you’ll need:

  • cop­per(II) chlo­ride di­hy­drate, Cu­Cl2 (1/2 oz or 15 g);
  • ethanol, C2H5OH (96%) (1 cup or 240 mL);
  • toi­let pa­per (or dry nap­kins);
  • lighter;
  • spray bot­tle;
  • jack-o’-lantern.

What’s next?

  1. Mix the salt crys­tals with the al­co­hol (the salt will par­tial­ly dis­solve, cre­at­ing a green­ish so­lu­tion);
  2. In­sert the roll of toi­let pa­per or crum­pled dry nap­kins into the pump­kin, then thor­ough­ly wet with so­lu­tion;
  3. Spray the pump­kin from all sides with the al­co­hol so­lu­tion – this will make the ex­per­i­ment much more im­pres­sive.

When ig­nit­ed, the al­co­hol burns green. Why is this? The green tint is the re­sult of the cop­per ions from the salt. When heat­ed, they ab­sorb en­er­gy from the flame and lat­er re­lease this “ex­tra” en­er­gy as green light. Con­duct this ex­per­i­ment out­side and don’t leave your pump­kin unat­tend­ed.

Ob­serve fire safe­ty pre­cau­tions when con­duct­ing this ex­per­i­ment!

Smok­ing Jack-O’-Lantern

Want to add some va­ri­ety to Hal­loween’s most renowned sym­bol – the Jack-o'-lantern? Just use plain old glyc­erin!

To make “smol­der­ing” pump­kin, you’ll need:

  • glyc­erin, C₃H₅(OH)₃ (1 tsp or 5 mL);
  • 3 small can­dles;
  • 1 alu­minum can;
  • scis­sors;
  • pipette (to trans­fer glyc­erin);
  • jack-o’-lantern (be sure to save the top - it will serve as a lid!).

What’s next?

1)Set a few can­dles in the pump­kin and light them; 2) Cut an alu­minum can to make a stand as shown in the video; 3) Drip some glyc­erin into the hol­low of the can; 4) Place the lid (saved from when you carved your pump­kin) on your jack-o’-lantern.

Why does the glyc­erin va­por ap­pear? The can­dles warm the alu­minum, and the glyc­erin be­gins to va­por­ize in the heat, turn­ing into white, smoky clouds. This makes for a tru­ly ter­ri­fy­ing pump­kin – it’s both glow­ing from the can­dles and re­leas­ing omi­nous smoke from its eyes and mouth!

Ob­serve fire safe­ty pre­cau­tions when con­duct­ing this ex­per­i­ment!

Flu­o­res­cent Jack-O’-Lantern

To make flu­o­res­cent pump­kin, you’ll need:

  • ethanol (40%) (1/6 cup or 40 mL);
  • flu­o­res­cent high­lighter (you’ll need its car­tridge);
  • cup;
  • paint­brush;
  • spray bot­tle;
  • black­light
  • jack-o’-lantern or pump­kin

What’s next?

  1. Re­move the car­tridge from the high­lighter and rinse it thor­ough­ly in al­co­hol to ex­tract its dye;
  2. Use the paint­brush to ap­ply the al­co­hol so­lu­tion to the pump­kin and wait for the al­co­hol to evap­o­rate;
  3. Turn on your black­light and en­joy the ef­fect: the whole pump­kin will glow!

This glow­ing pump­kin will look es­pe­cial­ly creepy and im­pres­sive un­der a black­light with the room lights off!

Why does the pump­kin glow? Many mark­ers con­tain dyes that glow in ul­tra­vi­o­let light. This in­ter­est­ing phe­nom­e­non is known as flu­o­res­cence.

Fake Blood

The in­gre­di­ents for this ex­per­i­ment can be found in any kitchen or con­ve­nience store!

To make fake blood, you’ll need:

  • wa­ter (1 1/4 cups or 300 mL);
  • sug­ar (8 oz or 230 g);
  • cit­ric acid or lemon juice (1 tsp or 5 g);
  • in­stant cof­fee (1 tsp or 5 g, op­tion­al);
  • food col­or­ing (red and blue) (2 Tbsp or 30 g);
  • reg­u­lar flour (1/8 cup or 20 g);
  • small pot or saucepan;
  • pump­kin or jack-o’-lantern.

What’s next?

  1. In the pot, mix wa­ter, cit­ric acid, and sug­ar, and bring to a boil;
  2. When the so­lu­tion cools, add the food col­or­ing (red and a few drops of blue). You can also add cof­fee to make the col­or more in­tense.
  3. To thick­en the “blood,” add some flour.

Why does the blood turn out so re­al­is­tic? Sug­ar mol­e­cules con­sist of glu­cose and fruc­tose. Cit­ric acid in­verts nor­mal sug­ar – that is, it makes a sug­ar syrup that con­tains not su­crose, but equal quan­ti­ties of glu­cose and fruc­tose. This serves to help the blood main­tain its ap­pear­ance over time. The flour has a dif­fer­ent pur­pose – it makes the fake blood thick­er. This blood is al­most in­dis­tin­guish­able vis­ual­ly from real blood! It can even be used for Hal­loween make­up; it is com­plete­ly safe. Just keep in mind that food col­or­ing isn’t al­ways easy to wash off!