A maze with chemistry

How can chemists solve a maze instantly?

Safe­ty pre­cau­tions

At­ten­tion! All ex­per­i­ments are per­formed by pro­fes­sion­als. Do not at­tempt.


  • soapy so­lu­tion of sodi­um hy­drox­ide;
  • sul­fu­ric acid;
  • labyrinth;
  • thy­molph­thalein so­lu­tion.

Process de­scrip­tion

Soap con­sists of fat­ty acid salts that low­er wa­ter’s sur­face ten­sion. A re­ac­tion with sul­fu­ric acid con­verts these salts to acids at the end of the labyrinth. At this point, the wa­ter’s sur­face ten­sion, con­verse­ly, in­creas­es. This sur­face ten­sion dif­fer­ence forces liq­uid to move from the start to the end along the short­est path. More­over, this stream is col­ored with thy­molph­thalein, as it turns blue in an al­ka­line en­vi­ron­ment. Thus, the maze can be solved in­stant­ly!

A safer ver­sion of this ex­per­i­ment is in­clud­ed in the “Chem­istry in mo­tion” set from the MEL Chem­istry sub­scrip­tion