39. Kodi acidity m'madzi ndi alkalinity ndi chiyani?
Kuchuluka kwa madzi kumatanthawuza kuchuluka kwa zinthu zomwe zili m'madzi zomwe zimatha kusokoneza maziko amphamvu. Pali mitundu itatu ya zinthu zomwe zimapanga acidity: ma asidi amphamvu omwe amatha kusiyanitsa H+ (monga HCl, H2SO4), ma acid ofooka omwe amalekanitsa pang'ono H+ (H2CO3, organic acids), ndi mchere wopangidwa ndi asidi amphamvu ndi maziko ofooka (monga NH4Cl, FeSO4). Acidity imayesedwa ndi titration ndi njira yolimba yoyambira. The acidity kuyeza ndi methyl lalanje monga chizindikiro pa titration amatchedwa methyl lalanje acidity, kuphatikizapo asidi opangidwa ndi mtundu woyamba wa asidi amphamvu ndi mtundu wachitatu wa asidi asidi mchere; acidity yoyezedwa ndi phenolphthalein monga chizindikirocho imatchedwa phenolphthalein acidity, Ndichiwerengero cha mitundu itatu ya acidity pamwambapa, motero imatchedwanso acidity yonse. Madzi achilengedwe nthawi zambiri sakhala ndi asidi amphamvu, koma amakhala ndi ma carbonates ndi ma bicarbonates omwe amapangitsa kuti madziwo akhale amchere. Pakakhala asidi m’madzi, nthawi zambiri zimatanthauza kuti madziwo aipitsidwa ndi asidi.
Mosiyana ndi acidity, alkalinity yamadzi imatanthawuza kuchuluka kwa zinthu zomwe zili m'madzi zomwe zimatha kusokoneza ma asidi amphamvu. Zinthu zomwe zimapanga alkalinity zimaphatikizapo maziko amphamvu (monga NaOH, KOH) omwe amatha kusiyanitsa kwathunthu OH-, maziko ofooka omwe amalekanitsa pang'ono OH- (monga NH3, C6H5NH2), ndi mchere wopangidwa ndi maziko amphamvu ndi asidi ofooka (monga Na2CO3, K3PO4, Na2S) ndi magulu ena atatu. Kuchuluka kwa alkalinity kumayesedwa ndi titration ndi njira yolimba ya asidi. Mchere wamchere woyezedwa pogwiritsa ntchito methyl lalanje monga chizindikiro panthawi ya titration ndi kuchuluka kwa mitundu itatu ya alkalinity yomwe ili pamwambayi, yomwe imatchedwa alkalinity yonse kapena methyl orange alkalinity; alkalinity anayeza ntchito phenolphthalein monga chizindikiro amatchedwa phenolphthalein maziko. Digiri, kuphatikizapo mchere wopangidwa ndi mtundu woyamba wa m'munsi amphamvu ndi mbali ya alkalinity yopangidwa ndi mtundu wachitatu wa mchere wamphamvu zamchere.
Njira zoyezera za acidity ndi alkalinity zikuphatikizapo acid-base indicator titration ndi potentiometric titration, zomwe nthawi zambiri zimasinthidwa kukhala CaCO3 ndikuyesedwa mu mg/L.
40.Kodi pH yamadzi ndi chiyani?
Phindu la pH ndi logarithm yolakwika ya hydrogen ion zochita mu njira yamadzi yoyezera, ndiye pH=-lgαH+. Ndi chimodzi mwa zizindikiro zomwe zimagwiritsidwa ntchito kwambiri pazitsulo zamadzimadzi. Pansi pa 25oC mikhalidwe, pamene pH mtengo ndi 7, zochita za ayoni wa haidrojeni ndi ayoni a hydroxide m'madzi ndi ofanana, ndipo ndende yofananira ndi 10-7mol/L. Panthawiyi, madziwo salowerera, ndipo pH mtengo> 7 imatanthauza kuti madzi ndi amchere. , ndi pH mtengo<7 means the water is acidic.
Phindu la pH limasonyeza acidity ndi alkalinity ya madzi, koma silingasonyeze mwachindunji acidity ndi alkalinity ya madzi. Mwachitsanzo, acidity ya 0.1mol/L hydrochloric acid solution ndi 0.1mol/L acetic acid solution ndi 100mmol/L, koma ma pH awo ndi osiyana kwambiri. Mtengo wa pH wa 0.1mol/L hydrochloric acid solution ndi 1, pamene pH mtengo wa 0.1 mol/L acetic acid solution ndi 2.9.
41. Kodi njira zoyezera mtengo wa pH zomwe zimagwiritsidwa ntchito kwambiri ndi ziti?
Pakupanga kwenikweni, kuti muzindikire mwachangu komanso mosavuta kusintha kwa pH yamadzi onyansa omwe amalowa m'malo opangira madzi oyipa, njira yosavuta ndiyo kuyesa pafupifupi ndi pepala loyesa pH. Kwa madzi otayira opanda mtundu opanda zonyansa zoyimitsidwa, njira za colorimetric zitha kugwiritsidwanso ntchito. Pakali pano, dziko langa njira muyezo kuyeza pH mtengo wa madzi khalidwe ndi njira potentiometric (GB 6920-86 galasi elekitirodi njira). Nthawi zambiri sizimakhudzidwa ndi mtundu, turbidity, colloidal zinthu, oxidants, ndi othandizira kuchepetsa. Ikhozanso kuyeza pH ya madzi oyera. Itha kuyezanso kuchuluka kwa pH yamadzi otayidwa m'mafakitale oipitsidwa ndi magawo osiyanasiyana. Iyinso ndi njira yomwe imagwiritsidwa ntchito kwambiri kuyeza kuchuluka kwa pH m'malo ambiri opangira madzi oyipa.
Mfundo yoyezera potentiometric ya mtengo wa pH ndiyo kupeza kuthekera kwa electrode yosonyeza, ndiko kuti, mtengo wa pH, poyesa kusiyana komwe kulipo pakati pa electrode yagalasi ndi electrode yowonetsera ndi kuthekera kodziwika. Elekitikitilodi yowunikira nthawi zambiri imagwiritsa ntchito ma elekitirodi a calomel kapena ma elekitirodi a Ag-AgCl, pomwe ma elekitirodi a calomel amakhala omwe amagwiritsidwa ntchito kwambiri. Pakatikati pa pH potentiometer ndi DC amplifier, yomwe imakulitsa kuthekera kopangidwa ndi electrode ndikuyiwonetsa pamutu wa mita ngati manambala kapena zolozera. Potentiometers nthawi zambiri amakhala ndi chipangizo cholipirira kutentha kuti akonze momwe kutentha kumayendera.
Mfundo yogwiritsira ntchito mita ya pH ya pa intaneti yomwe imagwiritsidwa ntchito m'mafakitale otsuka madzi oyipa ndi njira ya potentiometric, ndipo njira zopewera zogwiritsira ntchito ndizofanana ndi za labotale pH metres. Komabe, chifukwa maelekitirodi ntchito mosalekeza ankawaviika m'madzi oipa kapena akasinja aeration ndi malo ena okhala ndi kuchuluka kwa mafuta kapena tizilombo kwa nthawi yaitali, kuwonjezera pa amafuna pH mita kukhala okonzeka ndi basi kuyeretsa chipangizo kwa maelekitirodi, Buku. kuyeretsa kumafunikanso potengera momwe madzi alili komanso momwe amagwirira ntchito. Nthawi zambiri, mita ya pH yomwe imagwiritsidwa ntchito m'madzi olowera kapena m'thanki ya mpweya imayeretsedwa pamanja kamodzi pa sabata, pomwe mita ya pH yomwe imagwiritsidwa ntchito m'madzi otayira imatha kutsukidwa pamanja kamodzi pamwezi. Pamamita a pH omwe amatha kuyeza kutentha ndi ORP ndi zinthu zina, ayenera kusamalidwa ndi kusamalidwa molingana ndi njira zomwe zimafunikira pakuyezera.
42.Kodi njira zodzitetezera poyezera pH mtengo ndi ziti?
⑴Potentiometer iyenera kukhala yowuma komanso yopanda fumbi, kuyatsidwa pafupipafupi kuti ikonzedwe, ndipo gawo lolumikizira lolowera la elekitirodi liyenera kukhala loyera kuti madontho amadzi, fumbi, mafuta, ndi zina zotere asalowe. Onetsetsani malo abwino mukamagwiritsa ntchito mphamvu ya AC. Ma potentiometer onyamula omwe amagwiritsa ntchito mabatire owuma ayenera kusintha mabatire pafupipafupi. Panthawi imodzimodziyo, potentiometer iyenera kusinthidwa nthawi zonse ndikuyimitsidwa kuti iwonetsedwe ndi kukonza. Ikasinthidwa bwino, zero point ya potentiometer ndi ma calibration ndi malo owongolera sangathe kusinthidwa mwakufuna panthawi ya mayeso.
⑵Madzi omwe amagwiritsidwa ntchito pokonzekera njira yopangira bafa ndi kutsuka ma elekitirodi asakhale ndi CO2, akhale ndi pH yapakati pa 6.7 ndi 7.3, komanso ma conductivity osakwana 2 μs/cm. Madzi opangidwa ndi anion ndi cation exchange resin amatha kukwaniritsa izi atatha kuwira ndikusiya kuti zizizizira. Yankho lokonzekera lokhazikika liyenera kusindikizidwa ndikusungidwa mu botolo lagalasi lolimba kapena botolo la polyethylene, ndikusungidwa mufiriji pa 4oC kuti atalikitse moyo wautumiki. Ngati zasungidwa panja kapena kutentha kwa firiji, moyo wautumiki nthawi zambiri sungapitirire 1 Miyezi, buffer yomwe idagwiritsidwa ntchito siyingabwezedwe ku botolo losungira kuti ligwiritsidwenso ntchito.
⑶ Musanayezedwe moyenera, fufuzani kaye ngati chidacho, ma elekitirodi, ndi bafa wamba ndi zabwinobwino. Ndipo pH mita iyenera kusinthidwa pafupipafupi. Nthawi zambiri ma calibration cycle ndi kotala kapena theka la chaka, ndipo njira ya calibration ya mfundo ziwiri imagwiritsidwa ntchito poyesa. Ndiye kuti, kutengera mtundu wa pH wa zitsanzo zomwe zimayenera kuyesedwa, mayankho awiri omwe ali pafupi nawo amasankhidwa. Nthawi zambiri, kusiyana kwa pH pakati pa ma bafa awiriwa kuyenera kukhala kwakukulu kuposa 2. Mukayika yankho loyamba, yesaninso yankho lachiwiri. Kusiyana pakati pa zotsatira zowonetsera za potentiometer ndi mulingo wa pH wa njira yachiwiri ya bafa sikuyenera kupitilira 0.1 pH unit. Ngati cholakwikacho ndi chachikulu kuposa 0.1 pH unit, njira yachitatu yokhazikika yokhazikika iyenera kugwiritsidwa ntchito poyesa. Ngati cholakwikacho chili chochepera 0.1 pH mayunitsi panthawiyi, pangakhale vuto ndi yankho lachiwiri la buffer. Ngati cholakwikacho chikadali chachikulu kuposa 0.1 pH unit, pali cholakwika ndi electrode ndipo electrode iyenera kukonzedwa kapena kusinthidwa ndi yatsopano.
⑷Mukachotsa chotchinga chokhazikika kapena sampuli, electrode iyenera kutsukidwa bwino ndi madzi osungunuka, ndipo madzi omwe amaphatikizidwa ndi electrode amayenera kuyamwa ndi pepala losefera, kenako nkutsukidwa ndi yankho kuti ayezedwe kuti athetse kukhudzidwa. Izi ndizofunikira pakugwiritsa ntchito ma buffer ofooka. Izi ndizofunikira makamaka mukamagwiritsa ntchito mayankho. Poyezera pH, njira yamadzimadzi iyenera kugwedezeka moyenera kuti yankho likhale lofanana ndi kukwaniritsa electrochemical equilibrium. Poŵerenga, kusonkhezerako kuyenera kuimitsidwa ndi kuloledwa kuimirira kwa kanthaŵi kuti kuŵerenga kukhale kokhazikika.
⑸ Poyesa, choyamba mutsuka maelekitirodi awiri mosamala ndi madzi, kenaka mutsuka ndi madzi, kenaka mizereni maelekitirodi mu beaker yaing'ono yomwe ili ndi madzi, gwedezani beaker mosamala ndi manja anu kuti mupange yunifolomu ya madzi, ndi kulemba Phindu la pH pambuyo powerenga likhazikika.
Nthawi yotumiza: Oct-26-2023
