“Сombustible gel” experiment

Have you just eat­en a boiled egg? Don’t throw away the shell – you can make fuel from it!

Safe­ty pre­cau­tions

Wear pro­tec­tive gloves, glass­es and a mask and work in a well-ven­ti­lat­ed room.

Warn­ing! Only un­der adults su­per­vi­sion.

Reagents and equip­ment:

• eggshell (50 g, or you can also use chalk or build­ing lime);
• 70% vine­gar (50 ml);
• wa­ter;
• 96% ethyl al­co­hol;
• glass;
• rod;
• lid for the beaker;
• glass con­tain­er.

Step-by-step in­struc­tions

Put the eggshell in the glass and pour acetic acid over it. Then add 30 ml of wa­ter. Close with a lid and keep it for a week in a place that is in­ac­ces­si­ble to chil­dren and an­i­mals. Then add 30 ml of wa­ter to the glass and stir thor­ough­ly. Fil­ter the ob­tained so­lu­tion through a fun­nel with cot­ton wool. In a few sec­onds the so­lu­tion will turn into gel.

Pro­cess­es de­scrip­tion

Eggshells con­sist al­most en­tire­ly of cal­ci­um car­bon­ate. They dis­solve in acetic acid, form­ing cal­ci­um ac­etate. If ethyl al­co­hol is added to a so­lu­tion of cal­ci­um ac­etate, a com­bustible gel forms which can be used as a fuel tablet. The gel forms be­cause cal­ci­um ions are sol­vat­ed by mol­e­cules of ethyl al­co­hol, which sur­round the cal­ci­um ions from all sides.

This gel should be stored in a sealed con­tain­er so that the al­co­hol does not evap­o­rate.