39.Asiti ea metsi le alkalinity ke eng?
Asiti ea metsi e bolela bongata ba lintho tse ka metsing tse ka fokotsang metheo e matla. Ho na le mefuta e meraro ea lintho tse etsang asiti: li-acid tse matla tse ka arohanyang H+ ka ho felletseng (joalo ka HCl, H2SO4), liasiti tse fokolang tse arolang H+ (H2CO3, organic acid), le letsoai le entsoeng ka li-acid tse matla le metheo e fokolang (joalo ka NH4Cl, FeSO4). Asiti e lekantsoe ka titration ka tharollo e matla ea motheo. Asiti e lekantsoeng ka methyl orange e le pontšo nakong ea titration e bitsoa methyl orange acidity, ho kenyelletsa le acidity e entsoeng ke mofuta oa pele oa acid e matla le mofuta oa boraro oa letsoai le matla; acidity e lekantsoeng ka phenolphthalein joalo ka ha sesupo se bitsoa acidity ea phenolphthalein, Ke kakaretso ea mefuta e meraro e kaholimo ea asiti, ka hona e boetse e bitsoa acidity eohle. Metsi a tlhaho ka kakaretso ha a na asiti e matla, empa a na le carbonates le bicarbonates tse etsang hore metsi a be alkaline. Ha ho na le asiti ka metsing, hangata ho bolela hore metsi a silafalitsoe ke asiti.
Ho fapana le acidity, alkalinity ea metsi e bolela bongata ba lintho tse ka metsing tse ka fokotsang li-acid tse matla. Lintho tse etsang alkalinity li kenyelletsa metheo e matla (e kang NaOH, KOH) e ka arolang ka ho feletseng OH-, metheo e fokolang e arolang ka mokhoa o itseng OH- (e kang NH3, C6H5NH2), le letsoai le entsoeng ka metheo e matla le li-acid tse fokolang (joaloka Na2CO3, K3PO4, Na2S) le mekhahlelo e meng e meraro. Alkalinity e lekantsoe ka titration ka tharollo e matla ea asiti. Alkalinity e lekantsoeng ho sebelisoa methyl orange e le pontšo nakong ea titration ke kakaretso ea mefuta e meraro e ka holimo ea alkalinity, e bitsoang total alkalinity kapa methyl orange alkalinity; alkalinity e lekantsoeng ho sebelisoa phenolphthalein joalo ka ha letšoao le bitsoa phenolphthalein base. Degree, ho kenyelletsa le alkalinity e entsoeng ke mofuta oa pele oa setsi se matla le karolo ea alkalinity e entsoeng ke mofuta oa boraro oa letsoai le matla la alkali.
Mekhoa ea ho lekanya acidity le alkalinity e kenyeletsa acid-base indicator titration le potentiometric titration, tseo ka kakaretso li fetoloang ho CaCO3 le ho lekanngoa ka mg/L.
40. pH boleng ba metsi ke eng?
Boleng ba pH ke logarithm e mpe ea tšebetso ea ion ea hydrogen tharollong e lekantsoeng ea metsi, ke hore, pH=-lgαH+. Ke e 'ngoe ea matšoao a sebelisoang ka ho fetisisa mosebetsing oa ho hloekisa likhoerekhoere. Tlas'a maemo a 25oC, ha pH ea boleng e le 7, mesebetsi ea li-ion tsa hydrogen le li-ion tsa hydroxide metsing lia lekana, 'me mahloriso a tšoanang ke 10-7mol / L. Ka nako ena, metsi ha a nke lehlakore, 'me pH ea boleng> 7 e bolela hore metsi ke alkaline. , le boleng ba pH<7 means the water is acidic.
Boleng ba pH bo bonahatsa acidity le alkalinity ea metsi, empa e ke ke ea bontša ka ho toba acidity le alkalinity ea metsi. Mohlala, acidity ea 0.1mol/L hydrochloric acid solution le 0.1mol/L acetic acid le eona ke 100mmol/L, empa boleng ba bona ba pH bo fapane haholo. Phaello ea pH ea 0.1mol/L hydrochloric acid solution ke 1, ha The pH value ea 0.1 mol/L acetic acid solution ke 2.9.
41. Mekhoa e tloaelehileng ea ho lekanya boleng ba pH ke efe?
Tlhahisong ea 'nete, e le ho utloisisa kapele le ha bonolo liphetoho tsa pH boleng ba metsi a litšila a kenang setsing sa ho hloekisa metsi a litšila, mokhoa o bonolo ka ho fetisisa ke ho o lekanya ka pampiri ea tlhahlobo ea pH. Bakeng sa metsi a litšila a se nang mebala ntle le litšila tse emisitsoeng, mekhoa ea colorimetric e ka boela ea sebelisoa. Hajoale, mokhoa o tloaelehileng oa naha ea heso oa ho lekanya boleng ba pH ba boleng ba metsi ke mokhoa oa potentiometric (mokhoa oa li-electrode tsa khalase tsa GB 6920-86). Hangata ha e amehe ke 'mala, turbidity, colloidal substances, oxidants, le lisebelisoa tse fokotsang. E ka boela ea lekanya pH ea metsi a hloekileng. E ka boela ea lekanya boleng ba pH ba metsi a litšila a indasteri a silafalitsoeng ka likhato tse fapaneng. Ona hape ke mokhoa o sebelisoang haholo oa ho lekanya boleng ba pH litsing tse ngata tsa ho hloekisa metsi a litšila.
Molao-motheo oa tekanyo ea potentiometric ea boleng ba pH ke ho fumana bokhoni ba electrode e bontšang, ke hore, boleng ba pH, ka ho lekanya phapang e ka bang teng pakeng tsa electrode ea khalase le electrode ea referense e nang le bokhoni bo tsejoang. Electrode ea litšupiso ka kakaretso e sebelisa eleketrode ea calomel kapa eleketrode ea Ag-AgCl, 'me electrode ea calomel ke eona e sebelisoang haholo. Moko oa pH potentiometer ke DC amplifier, e matlafatsang bokhoni bo hlahisoang ke electrode le ho e bontša hloohong ea mithara ka mokhoa oa linomoro kapa lintlha. Hangata li-potentiometers li na le sesebelisoa sa matšeliso a mocheso ho lokisa phello ea mocheso ho li-electrode.
Molao-motheo oa ts'ebetso oa meter ea pH ea marang-rang o sebelisoang litsing tsa ho hloekisa metsi a litšila ke mokhoa oa potentiometric, 'me litemoso tsa ts'ebeliso li ts'oana le tsa laboratori ea pH metres. Leha ho le joalo, hobane li-electrode tse sebelisoang li lula li kolobisitsoe ka metsing a litšila kapa litanka tsa aeration le libaka tse ling tse nang le oli e ngata kapa likokoana-hloko ka nako e telele, ntle le ho hloka hore pH meter e be le sesebelisoa sa ho hloekisa ka mokhoa o itekanetseng bakeng sa li-electrode. ho hloekisa ho boetse hoa hlokahala ho ipapisitse le maemo a boleng ba metsi le boiphihlelo ba ts'ebetso. Ka kakaretso, meter ea pH e sebelisoang ka har'a metsi a kenang kapa tanka ea aeration e hloekisoa ka letsoho hang ka beke, athe pH meter e sebelisoang metsing a litšila e ka hloekisoa ka letsoho hang ka khoeli. Bakeng sa limithara tsa pH tse ka methang mocheso le ORP le lintho tse ling ka nako e le 'ngoe, li lokela ho hlokomeloa le ho hlokomeloa ho latela litemoso tsa ts'ebeliso tse hlokahalang bakeng sa ts'ebetso ea ho metha.
42.Mehato ea ho lekanya pH ea boleng ke efe?
⑴Potentiometer e lokela ho bolokoa e omme 'me e sa kenelle lerole, e sebelisoa khafetsa bakeng sa tlhokomelo, 'me karolo ea khokahano ea lead lead ea eleketrode e lokela ho bolokoa e hloekile ho thibela marotholi a metsi, lerōle, oli, joalo-joalo. Netefatsa motheo o motle ha o sebelisa matla a AC. Li-potentiometer tse nkehang tse sebelisang libeteri tse ommeng li lokela ho nkela libeteri sebaka khafetsa. Ka nako e ts'oanang, potentiometer e tlameha ho lekanyetsoa khafetsa le ho beoa zero bakeng sa ho lekanya le ho hlokomela. Hang ha e se e lokisitsoe hantle, ntlha ea zero ea potentiometer le li-calibration le li-position regulators li ke ke tsa fetoloa ka thato nakong ea tlhahlobo.
⑵Metsi a sebelisitsoeng ho lokisa tharollo e tloaelehileng ea buffer le ho hlatsoa electrode ha ea lokela ho ba le CO2, a be le pH ea boleng pakeng tsa 6.7 le 7.3, le conductivity e ka tlase ho 2 μs/cm. Metsi a hloekisitsoeng ka anion le resin ea cation exchange a ka fihlela tlhokahalo ena ka mor'a ho belisoa le ho o tlohela hore o pholile. Tharollo e lokisitsoeng e tloaelehileng ea buffer e lokela ho koaloa le ho bolokoa ka botlolong ea khalase e thata kapa botlolo ea polyethylene, ebe e bolokoa ka sehatsetsing sa 4oC ho lelefatsa bophelo ba tšebeletso. Haeba e bolokiloe sebakeng se bulehileng kapa mocheso oa kamore, bophelo ba ts'ebeletso ka kakaretso bo ke ke ba feta Likhoeli tse 1, buffer e sebelisitsoeng e ke ke ea khutlisetsoa botlolong ea polokelo hore e sebelisoe hape.
⑶ Pele u etsa litekanyo tse hlophisitsoeng, qala ka ho hlahloba hore na sesebelisoa, li-electrode le buffer e tloaelehileng li tloaelehile. 'Me pH meter e lokela ho lekanyetsoa khafetsa. Hangata saekele ea calibration ke kotara e le 'ngoe kapa halofo ea selemo,' me mokhoa oa ho lekanya lintlha tse peli o sebelisoa bakeng sa ho lekanya. Ke hore, ho latela boleng ba pH ba sampole e lokelang ho lekoa, ho khethoa litharollo tse peli tse tloaelehileng tse haufi le eona. Ka kakaretso, phapang ea pH pakeng tsa litharollo tse peli tsa buffer e tlameha ho ba bonyane ho feta 2. Kamora ho beha tharollo ea pele, leka tharollo ea bobeli hape. Phapano lipakeng tsa sephetho sa ponts'o ea potentiometer le boleng bo tloaelehileng ba pH ba tharollo ea buffer e tloaelehileng ea bobeli ha ea lokela ho ba kholo ho feta 0.1 pH unit. Haeba phoso e le kholo ho feta yuniti ea pH ea 0.1, tharollo e tloaelehileng ea "buffer" e lokela ho sebelisoa bakeng sa tlhahlobo. Haeba phoso e le ka tlase ho 0.1 pH units ka nako ena, ho ka etsahala hore ebe bothata bo teng ka tharollo ea buffer ea bobeli. Haeba phoso e ntse e le kholo ho feta 0.1 pH unit, ho na le ho hong ho phoso ka electrode mme electrode e hloka ho sebetsoa kapa ho nkeloa sebaka ka e ncha.
⑷ Ha o nkela sebaka sa "buffer" kapa sampole e tloaelehileng, elektrode e lokela ho hlatsuoa ka botlalo ka metsi a silafetseng, 'me metsi a khomaretsoeng ho electrode a lokela ho kenngoa ka pampiri ea sefa, ebe e hlatsuoa ka tharollo e lokelang ho lekanyetsoa ho felisa tšusumetso e tšoanang. Sena se bohlokoa bakeng sa tšebeliso ea li-buffers tse fokolang. Sena ke sa bohlokoa haholo ha u sebelisa litharollo. Ha u lekanya boleng ba pH, tharollo e nang le metsi e lokela ho tsosoa ka mokhoa o nepahetseng ho etsa hore tharollo e tšoane le ho finyella tekano ea electrochemical. Ha ho bala, ho sisinyeha ho lokela ho emisoa ’me ho tloheloe ho ema ka nakoana ho etsa hore ’malo o tsitse.
⑸ Ha u lekanya, qala ka ho hlatsoa li-electrode tse peli ka hloko ka metsi, ebe u li hlatsoa ka sampole ea metsi, ebe u qoelisa li-electrode ka bekeng e nyane e nang le sampole ea metsi, sisinya beaker ka hloko ka matsoho a hau ho etsa sampole ea metsi, 'me u tlalehe pH boleng ka mor'a hore ho bala ho tsitsitse.
Nako ea poso: Oct-26-2023
