Fake chemical cut

How to make artificial blood

Oh, no! You slipped and cut your hand on a plas­tic knife! Wait, what…?

Safe­ty pre­cau­tions

Do not try it at home! Per­form this ex­per­i­ment only un­der pro­fes­sion­al su­per­vi­sion.

Equip­ment and reagents

  • iron(III) chlo­ride;
  • potas­si­um thio­cyanate;
  • sodi­um flu­o­ride;
  • wa­ter;
  • plas­tic knife;
  • cot­ton wool;
  • tweez­ers.

Step-by-step in­struc­tions

Pre­pare so­lu­tions of iron(III) chlo­ride, potas­si­um thio­cyanate, and sodi­um flu­o­ride by dis­solv­ing the re­spec­tive reagents in wa­ter. Soak a cot­ton ball in the so­lu­tion of potas­si­um thio­cyanate, then rub the cot­ton ball on your hand. Dip a plas­tic knife in the so­lu­tion of iron(III) chlo­ride and draw it gen­tly across your palm. This cre­ates a bloody “cut” on your hand! Treat it by wip­ing a cot­ton swab dipped in the sodi­um flu­o­ride so­lu­tion across the “wound.” Your hand is safe and sound!

Pro­cess­ de­scrip­tion

Nat­u­ral­ly, there was nev­er any blood on your hand. What you ob­served was a chem­i­cal re­ac­tion that oc­curs be­tween the so­lu­tions of potas­si­um thio­cyanate and iron(III) chlo­ride. Thio­cyanate ions and fer­ric ions form com­plex, blood-red com­pounds, the most well-known of which be­ing iron(III) thio­cyanate:

Fe­Cl₃ + 3KSCN=Fe(CNS)₃ + 3KCl

Adding sodi­um flu­o­ride de­stroys the iron(III) thio­cyanate com­plex­es, and col­or­less hex­aflu­o­ro­fer­rate(III) [FeF₆]³¯ ions form.

Fe(CNS)₃ + 6NaF=Na₃[FeF₆] + 3NaC­NS