Fiery Hand

Safe­ty pre­cau­tions

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

Equip­ment:

• glass con­tain­er with wa­ter;
• liq­uid soap;
• flammable gas;
• lighter.

Step-by-step in­struc­tions

Some liq­uid soap is poured into a glass con­tain­er with wa­ter. The so­lu­tion is stirred. A flammable gas is passed through the so­lu­tion. Af­ter dip­ping a hand in the so­lu­tion, the ex­per­i­menter col­lects some foam in the palm of the same hand and ig­nites it. The foam burns with­out burn­ing the ex­per­i­menter’s hand!

Process de­scrip­tion

Re­ac­tions that ab­sorb heat are called “en­dother­mic re­ac­tions,” while re­ac­tions that re­lease heat are re­ferred to as “exother­mic re­ac­tions.” For ex­am­ple, com­bus­tion is an exother­mic process, which is why we feel heat em­a­nat­ing from fire. Mean­while, wa­ter evap­o­rat­ing or ice melt­ing are ex­am­ples of en­dother­mic pro­cess­es. This ex­per­i­ment in­volves both types of re­ac­tions – when the flammable gas in the foam burns, a large amount of heat is re­leased, which is im­me­di­ate­ly spent on evap­o­rat­ing the wa­ter cov­er­ing the hand. As a re­sult, the fire does not burn the hand!

Safe ex­per­i­ments await you in the MEL Chem­istry sub­scrip­tion!