“Colored Flame” experiment

Ноw to turn a flame different colors

We're all used to flame be­ing yel­lowy-or­ange. But can we turn a flame dif­fer­ent col­ors? For ex­am­ple, blue, red or green? In our ex­per­i­ment, we will show you how to turn flame bright col­ors with salts.

Reagents and equip­ment:

  • alu­minum cups;
  • sodi­um chlo­ride (10 g);
  • cop­per(II) chlo­ride di­hy­drate (10 g);
  • stron­tium chlo­ride (10 g);
  • bar­i­um ni­trate (10 g);
  • lithi­um bro­mide (10 g);
  • ethyl al­co­hol (96%);
  • lighter.

Step-by-step in­struc­tions

Sprin­kle 10 g of salts into the alu­minum cups (for ex­am­ple the kind used as can­dle hold­ers). Then add 5-10 g of 96% ethyl al­co­hol, light it. Af­ter a while the flame of the al­co­hol will turn dif­fer­ent col­ors.

Pro­cess­es de­scrip­tion

Many ions of met­als and non-met­als turn flame dif­fer­ent col­ors. This is be­cause when heat­ed, atoms move to an ex­cit­ed (or un­sta­ble) state. When they re­turn to their orig­i­nal (sta­ble) state, the ex­cess of ac­cu­mu­lat­ed en­er­gy is re­leased in the form of light of a cer­tain wave­length, which is char­ac­ter­ized by the col­or we ob­serve. This amaz­ing prop­er­ty is used to make col­ored fire­works, in qual­i­ta­tive anal­y­sis of min­er­als, as a cer­tain ion cor­re­sponds to a cer­tain wave­length of col­or emit­ted. For ex­am­ple, sodi­um ions give a yel­low col­or, which we can ob­serve when heat­ing soup on a gas stove. Potas­si­um ions give a dark pink col­or, which we can ob­serve when pre­par­ing a recipe which uses wine – wine con­tains potas­si­um tar­trate, potas­si­um salt and tar­tar­ic acid. Boric acid gives a green col­or be­cause of the pres­ence of boron. Bar­i­um salt gives a yel­lowy-green col­or, cop­per salts — green, cal­ci­um salts — brick-red, stron­tium — a crim­son col­or, etc.

Safe­ty pre­cau­tions

Wear pro­tec­tive gloves and glass­es and work in a well-ven­ti­lat­ed room. Ob­serve safe­ty rules when work­ing with fire and flammable liq­uids.

Warn­ing! Don’t try to re­peat this ex­per­i­ment with­out a pro­fes­sion­al su­per­vi­sion!