Weird Science

Kitchen Chemistry: Glow-in-the-Dark Reactions for Everyone

Polish ver­sion is here

The fol­lo­wing article was ori­gi­nally publi­shed in the jour­nal for edu­ca­tors Che­mia w Szkole (eng. Che­mi­stry in School) (2/2025):

Ilustracja

Ples M., Che­mi­lu­mi­ne­scen­cja z kuchni - reak­cja dla każd­ego (eng. Kit­chen Che­mi­stry: Glow-in-the-Dark Reac­tions for Eve­ry­one), Che­mia w Szkole (eng. Che­mi­stry in School), 2 (2025), pp. 40–42

Che­mi­stry holds many fasci­na­ting secrets, and some of them can be disco­ve­red right in our kit­chens. Lear­ning che­mi­stry doesn't have to be dif­fi­cult or boring — in fact, it can be an incre­di­bly rewar­ding and exci­ting expe­rience. Con­duc­ting expe­ri­ments helps us bet­ter under­stand the world aro­und us and enhan­ces our logi­cal thin­king skills. With sim­ple expe­ri­ments, we can wit­ness che­mi­cal pro­ces­ses that usu­ally remain hid­den to the naked eye.

One of the most extra­or­di­nary che­mi­cal phe­no­mena is che­mi­lu­mi­ne­scence — a pro­cess in which sub­stan­ces emit light without hea­ting. We can obse­rve it in nature, for instance, in fire­flies Lam­py­ris or some marine orga­ni­sms [1]. Che­mi­lu­mi­ne­scence has fasci­na­ted humans for cen­tu­ries — first in its natu­ral form as bio­lu­mi­ne­scence, and later thro­ugh arti­fi­cially deve­lo­ped reac­tion sys­tems, some of which are sur­pri­sin­gly easy to recre­ate in a home lab [2] [3]. Today, it finds appli­ca­tions in medi­cine, foren­sic science, and even in the enter­ta­in­ment indu­stry.

Che­mi­lu­mi­ne­scence is one of the few phe­no­mena that allow for the direct conver­sion of energy into light without pro­du­cing heat. This means that such reac­tions can be use­ful in pla­ces where tra­di­tio­nal light sour­ces are imprac­ti­cal, such as in caving expe­di­tions.

Unfor­tu­na­tely, many che­mi­lu­mi­ne­scent reac­tions requ­ire rela­ti­vely expen­sive, rare, or toxic sub­stan­ces. On the other hand, there are some pro­ces­ses that can be car­ried out easily and safely. One of them is what I’d like to share with you today, dear rea­ders, as it pro­vi­des an excel­lent oppor­tu­nity to bet­ter under­stand energy trans­for­ma­tions during che­mi­cal reac­tions.

What Do We Need?

I stum­bled upon this expe­ri­ment while brow­sing thro­ugh old issues of the Jour­nal of Che­mi­cal Edu­ca­tion, where John­son descri­bed his work with che­mi­lu­mi­ne­scence using plant extracts [4]. The topic see­med both fasci­na­ting and some­what for­got­ten, so I deci­ded to recre­ate the expe­ri­ment myself — sub­sti­tu­ting the ori­gi­nally used lima beans (Pha­se­o­lus luna­tus) with more rea­dily ava­i­la­ble peas (Pisum sati­vum), a com­mon annual legume from the Faba­ceae family. Peas ori­gi­nate from Western Asia, the Cau­ca­sus, North Africa, Sou­thern and Eastern Europe, and are now cul­ti­va­ted in many parts of the world [5]. For the expe­ri­ment, dried and shel­led peas are espe­cially sui­ta­ble (Photo 1). Since they are used in coo­king, you can easily buy them at a gro­cery store.

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Photo 1 - Pea seeds used in the expe­ri­ment

In addi­tion to peas, you’ll need the fol­lo­wing che­mi­cals:

Hydro­gen pero­xide at 3% con­cen­tra­tion is widely used as a disin­fec­tant for cle­a­ning wounds and for ble­a­ching hair or fabrics. It is rela­ti­vely safe at this con­cen­tra­tion but may irri­tate the skin or mucous mem­bra­nes upon pro­lon­ged con­tact. If inge­sted in large amo­unts, it can cause nau­sea.

Potas­sium or sodium hydro­xide are strong bases used in soap-making, cle­a­ning agents, and indu­strial pro­ces­ses. They are highly cau­stic and can cause severe skin burns and eye damage. Their vapors can irri­tate the respi­ra­tory sys­tem. Dis­so­lving them in water rele­a­ses con­si­de­ra­ble heat, incre­a­sing the risk of burns.

Sodium hypo­ch­lo­rite, com­monly known as ble­ach, also acts as a disin­fec­tant. It is highly cor­ro­sive and can damage skin, eyes, and air­ways. When mixed with acids (like vine­gar) or ammo­nia, it rele­a­ses toxic gases (chlo­rine Cl2 and chlo­ra­mine NH2Cl). For this expe­ri­ment, use hou­se­hold ble­ach — pre­fe­ra­bly a bud­get-frien­dly brand, as it con­ta­ins fewer addi­ti­ves.

Ethyl alco­hol with a con­cen­tra­tion of 70% or more is an effec­tive disin­fec­tant that destroys bac­te­rial and viral cell mem­bra­nes. It is flam­ma­ble and its vapors may ignite near open fla­mes. Con­su­med in large quan­ti­ties, it is toxic to the nervous sys­tem and liver — tho­ugh it rema­ins one of the most widely used recre­a­tio­nal sub­stan­ces.

The gre­a­test risks in this expe­ri­ment come from the strong bases and sodium hypo­ch­lo­rite due to their cor­ro­sive and reac­tive pro­per­ties. Always use appro­priate per­so­nal pro­tec­tive equ­ip­ment.

Addi­tio­nally, you’ll need some basic lab equ­ip­ment and glas­sware.

Pre­pa­ra­tions

The first step toward our glo­wing goal is to pre­pare a pea extract. Place about 20 g (0.7 oz) of dried peas into a bea­ker and pour in 50 cm3 (1.7 fl oz) of water. Bring it to a boil and con­ti­nue hea­ting for aro­und 15 minu­tes. After­ward, fil­ter out the solids and col­lect the aqu­e­ous extract, which may appear sli­gh­tly clo­udy with a yel­lo­wish tint (Photo 2).

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Photo 2 - Pea extract

The extract is unsta­ble, so it sho­uld be used shor­tly after coo­ling, or sto­red brie­fly in the refri­ge­ra­tor.

Next, pre­pare the fol­lo­wing solu­tions:

The Demon­stra­tion!

To per­form the expe­ri­ment, place 5 cm3 (0.17 fl oz) each of the pea extract and solu­tions A and B into a bea­ker (Photo 3).

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Photo 3 - Ready solu­tion

Dar­ken the room, allow your eyes to adjust for seve­ral seconds, then slowly pour in about 12 cm3 (0.4 fl oz) of solu­tion C. As the liqu­ids mix, you will obse­rve a faint but cle­arly visi­ble emis­sion of light — easily cap­tu­red in a pho­to­graph (Photo 4).

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Photo 4 - Che­mi­lu­mi­ne­scence (expo­sure time: 3s)

After the reac­tion, the solu­tion rema­ins clear (Photo 5) and can be dilu­ted and safely pou­red down the sink.

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Photo 5 - Post-reac­tion solu­tion

Expla­na­tion

The light pro­du­ced in this reac­tion results from the oxi­da­tion of sub­stan­ces pre­sent in the peas. It’s dif­fi­cult to iden­tify the exact che­mi­cal spe­cies respon­si­ble for the che­mi­lu­mi­ne­scence, as it has not yet been tho­ro­u­ghly stu­died. Howe­ver, the reac­tion likely fol­lows a gene­ral scheme known from bet­ter-under­stood che­mi­lu­mi­ne­scent sys­tems:

X → [Y]* → Y + hν

The reac­tant (or reac­tants) X pro­duce an inter­me­diate [Y]* in a high-energy exci­ted state. This exci­ted state is unsta­ble and decays into a gro­und state Y, rele­a­sing energy. In the case of che­mi­lu­mi­ne­scence, this energy is emit­ted as elec­tro­ma­gne­tic radia­tion — in other words, light.

Inte­re­stin­gly, other plant mate­rials can be used instead of peas — I’ve tested pea­nuts (Ara­chis hypo­gaea), and they also pro­du­ced a visi­ble glow.

Nota­bly, this reac­tion is men­tio­ned in Sha­kha­shiri’s renow­ned book, Che­mi­cal Demon­stra­tions: A Hand­book for Tea­chers of Che­mi­stry. Sur­pri­sin­gly, he does not recom­mend it for edu­ca­tio­nal use [6]. I respect­fully disa­gree. In my opi­nion, the abi­lity to demon­strate che­mi­lu­mi­ne­scence with ine­xpen­sive, acces­si­ble, and rela­ti­vely safe sub­stan­ces more than com­pen­sa­tes for the modest bri­ght­ness com­pa­red to other lumi­no­pho­res. This expe­ri­ment allows any­one curious eno­ugh to wit­ness the beauty of this remar­ka­ble che­mi­cal phe­no­me­non.

Refe­ren­ces:

  • [1] Ples M., Iskrzyk - żywa latar­nia (eng. Fire­fly - A Living Lan­tern), Bio­lo­gia w Szkole (eng. Bio­logy in School), 4 (2021), Forum Media Pol­ska Sp. z o.o., pp. 52-56 back
  • [2] Ples M., Całk­iem nie­zwy­kła her­batka (eng. A Rather Unu­sual Tea), Che­mia w Szkole (eng. Che­mi­stry in School), 4 (2015), Agen­cja AS Józef Szew­czyk, pp. 6-9 back
  • [3] Ples M., Czer­wono i nie­bie­sko - dwu­barwna che­mi­lu­mi­ne­scen­cja (eng. Red and Blue – Bi-Color Che­mi­lu­mi­ne­scence), Che­mia w Szkole (eng. Che­mi­stry in School), 3 (2024), Agen­cja AS Józef Szew­czyk, pp. 30-33 back
  • [4] John­son L. D., Che­mi­lu­mi­ne­scence or cold light inve­sti­ga­tions, Jour­nal of Che­mi­cal Edu­ca­tion, 17(6), 1940, pp. 295-296 back
  • [5] Borecki Z., Solen­berg M., Pol­skie nazwy cho­rób roślin upraw­nych, Pol­skie Towa­rzy­stwo Fito­pa­to­lo­giczne, Poznań, 2017 back
  • [6] Sha­kha­shiri B. Z., Che­mi­cal Demon­stra­tions, Volume 2: A Hand­book for Tea­chers of Che­mi­stry, The Uni­ver­sity of Wiscon­sin Press, 1983, pp. 201 back

    • All pho­to­gra­phs and illu­stra­tions were cre­a­ted by the author.

    The above text inc­lu­des minor edi­to­rial modi­fi­ca­tions com­pa­red to the ver­sion publi­shed in the jour­nal, aimed at sup­ple­men­ting and adap­ting it for online pre­sen­ta­tion.

    Marek Ples

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