“The Dumas reaction” experiment

There are no use­less ex­per­i­ments in chem­istry: ev­ery ex­per­i­ment in­volves phe­nom­e­na from ev­ery­day life in some way or an­oth­er. To­day you’ll find out the sim­plest method to ob­tain meth­ane.

Safe­ty pre­cau­tions

Con­duct the ex­per­i­ment in a ven­ti­lat­ed room, and work in pro­tec­tive glass­es, gloves and a mask. Ob­serve safe­ty rules when work­ing with flame and flammable sub­stances.

Warn­ing! Only un­der adults su­per­vi­sion.

Reagents and equip­ment:

• sodi­um ac­etate (5 g);
• sodi­um hy­drox­ide (5 g);
• test tube;
• spir­it burn­er;
• lighter;
• cork with gas pipe;
• stand with hold­er.

Step-by-step in­struc­tions

In a test tube, mix sodi­um hy­drox­ide and sodi­um ac­etate in the ra­tio of 1:1. Seal with a cork and heat. Ig­nite the gas that forms.

Pro­cess­es de­scrip­tion

This re­ac­tion is named af­ter the French chemist Jean-Bap­tiste An­dre Du­mas, and is a de­car­boxy­la­tion re­ac­tion, i.e. car­bon diox­ide splits off from an an­ion of car­bon­ic acid.

When car­bon­ic acids salts fuse with al­ka­lis (for ex­am­ple, with sodi­um hy­drox­ide), the car­bon diox­ide mol­e­cule splits off from the an­ion­ic residue of acid. The car­bon chain be­comes short­er by one car­bon atom, and an alka­ne is formed. In oth­er words, the de­car­boxy­la­tion of the an­ion­ic residue of acid takes place.

In our ex­per­i­ment, sodi­um ac­etate (its chain has two car­bon atoms) fus­es with sodi­um hy­drox­ide. Meth­ane forms (its chain has one car­bon atoms), and the car­bon diox­ide re­leased re­acts with sodi­um hy­drox­ide, form­ing sodi­um car­bon­ate:

СН₃СООН + NaOH → СН₄ ↑+ Na₂­CO₃