Kuyesa kwa botolo labuluu: kemistri, njira, ndi zomwe zimawonedwa

Botolo loyera limakhala patebulo la labotale. Limaoneka ngati lili ndi madzi. Munthu akaligwedeza, madziwo amasanduka abuluu owala kwambiri. Akalisiyanso pansi, mtundu wabuluu umatha mkati mwa mphindi imodzi kapena ziwiri. Liligwedezeninso ndipo mtundu wabuluu umabwerera. Kudzaza kamodzi kungabwereze izi nthawi twenty kapena kuposerapo.

Nthawi zambiri ophunzira amaganiza kuti chinachake chinali chobisika m’botolo, kapena kuti kugwedeza kunasakaniza zigawo ziwiri. Malingaliro onsewa amalephera m’njira yophunzitsira. Mtunduwu umachokera ku dye imodzi, methylene blue, yomwe ili m’madzi onsewo. Chomwe chimasintha ndi kuchuluka kwa ma electron amene dye imeneyo imanyamula. Chiwonetserochi ndi kuzungulira kwa redox komwe kwapangidwa kuti kuwoneke, ndipo variable iliyonse yomwe kalasi ingawone, nthawi yogwedeza, kutentha, concentration, imagwirizana ndi mbali inayake ya kemistriyo.

Mitundu iwiri ya dye yomweyo

Methylene blue yomwe ili oxidised ndi ring system yathyathyathya yokhala ndi charge yabwino. Imayamwa kwambiri kuzungulira 600 mpaka 700 nanometres, zomwe diso limaona ngati buluu wakuda. Mitundu iwiriyi ndi spectra zake zafotokozedwa mu kalozera wa kapangidwe ndi makhalidwe a methylene blue.

Reduction imawonjezera ma electron awiri ndi proton imodzi, kupanga leucomethylene blue: yopanda charge, yosakhala planar, ndipo kwenikweni yopanda mtundu. Mu alkaline solution, half-reaction imalembedwa MB+ + H2O + 2 e- ⇌ LMB + OH-. Gawo limeneli limatha kubwerera kwathunthu. Buluu amatanthauza oxidised, wopanda mtundu amatanthauza reduced, ndipo palibe state yachitatu yoti muzitsatira, zomwe zimapangitsa izi kukhala chiyambi chomveka bwino cha redox chemistry.

Kuzungulira: glucose imachepetsa, oxygen imabwezeretsa oxidation

Botololo lili ndi zinthu zitatu zogwira ntchito: methylene blue, glucose, ndi alkali yamphamvu, potassium kapena sodium hydroxide. Alkali imalimbikitsa glucose kukhala reactive deprotonated forms zomwe zimapereka ma electron kwa dye:

reducing sugar + MB (blue, oxidised) -> oxidised sugar products + LMB (colourless)

Gawo lochedwali limachotsa mtundu pamene botolo layima. Glucose ndi sacrificial donor ndipo imadyedwa. Dye imangonyamula ma electron kuchokera mbali ina kupita ina, choncho madontho ochepa amatha kugwira ntchito m’botolo lonse. Mafotokozedwe akale a m’kalasi amanena kuti glucose imasanduka gluconic acid. Kufupikitsa kumeneko kumatha kuneneratu zomwe zimawonedwa, koma aphunzitsi ayenera kudziwa kuti sikokwanira: mechanistic analysis yofalitsidwa mu Royal Society Open Science imatsatira oxidation kudzera mu reactive enediolate kupita ku dicarbonyl yomwe imasweka kukhala ma acid ang’onoang’ono.

Kugwedeza kumasintha zotsatira zomwe zikuwoneka. Kusokoneza madzi kumasungunula oxygen kuchokera mu mpweya wa headspace wotsekedwa, ndipo oxygen imabwezeretsa reduced dye kukhala oxidised:

LMB (colourless) + O2 -> MB (blue) + reduced oxygen products

Ikasiyidwa, dissolved oxygen imatha, glucose imachepetsanso dye, ndipo mtundu umatha. Pambuyo pa ma cycle ambiri, net chemistry yake ndi oxidation ya sugar ndi mpweya, pamene dye imazungulira popanda kusintha monga redox mediator. Ndi mediator osati strict catalyst, chifukwa sugar oxidation imachitikabe popanda iyo, ndipo kuzimiririka kwa mtundu si decomposition: dye yomwe yawonongeka sikanatha kubwezeretsedwa ndi kugwedeza. Kuti musunge dye stocks zokhazikika pakati pa ziwonetsero, onani zolemba za kagwiridwe ndi kasungidwe ka methylene blue solutions.

Njira ya chiwonetsero choyang’aniridwa

Ichi ndi chiwonetsero choyang’aniridwa, osati ntchito ya panyumba. Alkali imafuna chitetezo cha maso, magolovesi, ndi mphunzitsi amene ali ndi udindo wokonza ndi kuyeretsa. Ma formulation awiri olembedwa amagwirizana pa kapangidwe koma amasiyana pa scale.

Pepala la malangizo la chiwonetsero monga chinafalitsidwa ndi dipatimenti ya chemistry ya Indiana University limagwiritsa ntchito pafupifupi 5 percent potassium hydroxide, 4 percent glucose, ndi 1 percent aqueous methylene blue. Thirani ma volume ofanana a alkali ndi glucose solutions mu botolo loyera la 250 kapena 500 millilitre mpaka kufika pakati, ndipo siyani gawo lotsalalo ngati air headspace. Onjezani madontho ochepa a dye, tsekani, sindikizani seam, ndipo lisiyeni mpaka buluu atatha. Njira ya Royal Society of Chemistry imakulitsa lingaliro lomwelo kupita ku flask yotseka ya 1 litre: 300 millilitres ya madzi, 10 grams ya glucose, 8 grams ya potassium hydroxide (kapena 6 grams ya sodium hydroxide), kuphatikiza ma millilitres ochepa a dilute dye stock.

Kuti muchite, gwedezani mwamphamvu. Buluu wathunthu umaoneka mkati mwa masekondi. Ikani flask pansi ndipo yezani nthawi yomwe mtunduwo umatha. Royal Society of Chemistry imanena kuti kudzaza kamodzi kungapereke ma cycle oposa twenty. Musadzaze botolo mpaka pakamwa: popanda mpweya wotsekedwa mulibe oxygen reserve yoti isungunuke.

Zomwe muyenera kuona, ndi zomwe zimasintha nthawi yake

Yesani nthawi ya zinthu zitatu: kugwedeza mpaka kukhala buluu wathunthu (seconds), kuyima mpaka kukhala kopanda mtundu (up to a few minutes), ndi chiwerengero cha ma cycle mtundu wabuluu usanayambe kufooka. Pafupi ndi mapeto a kuzimiririka kulikonse, yang’anani pamwamba pa madzi. Wosanjikiza wabuluu woonda nthawi zambiri umatsalira pafupi ndi malire a mpweya, kumene oxygen imapitiriza kulowa mwa diffusion. Mzere umenewo ndi diffusion yomwe yawoneka ndi maso.

Blue bottle reaction imatsatira empirical rate law yomwe yafotokozedwa limodzi ndi njira ya Royal Society of Chemistry: rate = k[MB oxidised][glucose]OH-. Term iliyonse ndi kuyesa kwa m’kalasi. Glucose, alkali, kapena dye yochuluka imafupikitsa nthawi ya buluu. Kutentha kumathandizira kuti mtundu uthe mwachangu; flask yozizira imakhala yochedwa. Kugwedeza mwamphamvu kumasungunula oxygen yochuluka, choncho buluu umakhala nthawi yaitali. Headspace yaikulu imatalikitsa kuyesaku. Ma cycle akayamba kufooka ndipo madzi asanduka achikasu, sugar yatha ndipo side products zachuluka. Endpoint imeneyo yokha ndi zotsatira zofunika kulemba.

Pepala lolembera zomwe zawonedwa

Koperani tebulo ili m’mabuku, row imodzi pa trial iliyonse. Pepala ili limodzi ndi reaction diagram yomwe ili pamwambapa ndi zinthu zosindikizika za nkhaniyi.

Mafunso a prediction, oti ayankhidwe trial iliyonse isanayambe:

• Botolo ndi labuluu litangogwedezedwa. Ndi dye form iti yomwe ili yochuluka kwambiri, ndipo ndi chiyani chinaiyika mmenemo?
• Botolo layima ndipo mtundu ukutha. Ndi reaction iti yomwe ikupambana, ndipo ndi ingredient iti yomwe ikutha?
• Pambuyo pa ma cycle ambiri buluu umakhala wofooka ndi wachikasu pang’ono. Mubwezeretse ndi dye, alkali, kapena glucose, ndipo chifukwa chiyani?
• Jambulani colour against time pa cycle imodzi. Sonyezani pamene oxygen imalowa mu solution. Mayankho a mphunzitsi: (1) oxidised methylene blue, yobwezeretsedwa ku oxidation ndi dissolved headspace oxygen; (2) reduction ndi glucose, glucose ikudyedwa; (3) glucose, limiting donor, chifukwa dye imazungulira popanda kusintha; (4) kukwera mwadzidzidzi pakugwedeza, kutsika pang’onopang’ono ikayima, oxygen kulowa panthawi ya kukwerako kokha.

Mitundu yofanana yomwe ndi bwino kuitchula

Traffic light demonstration imagwiritsa ntchito indigo carmine m’malo mwake ndipo imadutsa mu yellow, red, ndi green pamene oxygenation ikusintha. Dzina lakuti green bottle limagwiritsidwa ntchito mosakhazikika: nthawi zina pa variant imeneyo, nthawi zina pa ma formulation obiriwira kwambiri monga ascorbic acid systems kapena enzymatic cycling system yofotokozedwa ndi American Chemical Society. Tchulani bwino variant yomwe ili patebulo kuti ophunzira asasokoneze zomwe awona kuchokera ku ma chemistry osiyanasiyana.

Chitetezo ndi kagwiridwe

Kuyang’aniridwa nthawi zonse. Gwiritsani ntchito chitetezo cha maso choletsa chemical splash ndi magolovesi pogwira alkaline solution kapena kugwedeza chotengera chotsekedwa. Alkali imawotcha, dye imadetsa khungu ndi nsalu, ndipo dye stocks zopangidwa mu ethanol zimawonjezera flammable solvent patebulo. Sungani chotengera chotsekedwa pamene mukugwedeza. Pambuyo pake, sungani spent solutions kuti zigwiridwe motsatira malamulo a labotale a bungwe lanu. Zofunikira pa alkaline waste yokhala ndi dye zimasiyana pakati pa mabungwe ndi madera ovomerezeka, choncho tsatirani njira yomwe labotale yanu imagwiritsa ntchito m'malo motenga ina kuchokera ku gwero lina.

Ngati mukufuna manambala osati kusintha kwa mtundu, quantitative assays ya methylene blue imayambira pamene chiwonetserochi chimathera.

Chifukwa chake aphunzitsi amasungabe botolo ili

Flask imodzi imaphatikiza malingaliro anayi. Redox imakhala mtundu m'malo mokhala tanthauzo lokha. Mediator imasonyeza mmene kuchuluka kochepa kwambiri kwa chinthu chimodzi kungasonyezere zomwe zikuchitika pa kuchuluka kwakukulu kwa china. Kinetics imasiyana ndi thermodynamics m’njira yooneka: oxygen imapambana pamene kugwedeza kukupitiriza kuipereka, glucose imapambana pamene kuperekako kwayima. Ndipo diffusion, njira yabata kwambiri mu chemistry, ndiyo imayendetsa chiwonetsero chonse, chifukwa kuwonekera kulikonse kwa buluu kumayamba ndi oxygen kuwoloka kuchokera mu mpweya kulowa m'madzi. Chiwonetsero chomwe chimathandiza ophunzira kuneneratu, kuyeza nthawi, ndi kufotokoza zonsezi pogwiritsa ntchito stopwatch ndi tebulo chayeneradi malo ake patebulo la labotale.