39. Menene acidity na ruwa da alkalinity?
Acidity na ruwa yana nufin adadin abubuwan da ke cikin ruwa wanda zai iya kawar da tushe mai karfi. Akwai nau'o'in abubuwa guda uku waɗanda ke haifar da acidity: acid mai ƙarfi wanda zai iya rabuwa da H+ gaba ɗaya (kamar HCl, H2SO4), raunin acid wanda ya raba H+ (H2CO3, Organic acids), da gishiri wanda ya ƙunshi acid mai karfi da ƙananan tushe (kamar su. NH4Cl, FeSO4). Ana auna acidity ta titration tare da maganin tushe mai ƙarfi. Acidity ɗin da aka auna tare da methyl orange a matsayin mai nuna alama yayin titration ana kiransa methyl orange acidity, gami da acidity ɗin da aka kafa ta nau'in acid mai ƙarfi na farko da nau'in gishiri mai ƙarfi na uku; acidity da aka auna da phenolphthalein kamar yadda mai nuna alama ake kira phenolphthalein acidity, Shi ne jimlar nau'ikan acidity guda uku da ke sama, don haka ana kiransa duka acidity. Ruwan dabi'a gabaɗaya baya ƙunsar ƙaƙƙarfan acidity, amma ya ƙunshi carbonates da bicarbonates waɗanda ke sanya ruwan alkaline. Idan akwai acidity a cikin ruwa, sau da yawa yana nufin cewa ruwan ya gurbata da ruwa.
Ya bambanta da acidity, alkalinity na ruwa yana nufin adadin abubuwan da ke cikin ruwa wanda zai iya kawar da acid mai karfi. Abubuwan da ke samar da alkalinity sun haɗa da tushe mai ƙarfi (kamar NaOH, KOH) waɗanda zasu iya rabuwa da OH gaba ɗaya, ginshiƙai masu rauni waɗanda ke raba OH- (kamar NH3, C6H5NH2), da salts waɗanda suka ƙunshi tushe mai ƙarfi da ƙarancin acid (kamar Na2CO3, K3PO4, Na2S) da sauran nau'ikan nau'ikan uku. Ana auna alkalinity ta titration tare da maganin acid mai ƙarfi. Alkalin da aka auna ta amfani da methyl orange a matsayin mai nuna alama yayin titration shine jimlar nau'ikan alkalinity guda uku na sama, wanda ake kira jimlar alkalinity ko methyl orange alkalinity; alkalinity da aka auna ta amfani da phenolphthalein a matsayin mai nuna alama ana kiran tushe phenolphthalein. Degree, ciki har da alkalinity kafa ta farko nau'i na karfi tushe da kuma wani ɓangare na alkalinity kafa ta uku irin karfi alkali gishiri.
Hanyoyin auna acidity da alkalinity sun haɗa da titration mai nuna alamar acid-tushe da titration mai ƙarfi, waɗanda galibi ana jujjuya su zuwa CaCO3 kuma ana auna su cikin mg/L.
40. Menene darajar pH na ruwa?
Ƙimar pH ita ce mummunan logarithm na ayyukan hydrogen ion a cikin ma'aunin bayani mai ruwa, wato pH = -lgαH +. Yana daya daga cikin alamomin da aka fi amfani da su a cikin tsarin kula da najasa. A ƙarƙashin yanayin 25oC, lokacin da ƙimar pH ta kasance 7, ayyukan ions hydrogen da ions hydroxide a cikin ruwa daidai suke, kuma daidaitaccen taro shine 10-7mol/L. A wannan lokacin, ruwan yana tsaka tsaki, kuma ƙimar pH> 7 yana nufin cewa ruwan shine alkaline. , da kuma pH darajar<7 means the water is acidic.
Ƙimar pH tana nuna acidity da alkalinity na ruwa, amma ba zai iya nuna kai tsaye ga acidity da alkalinity na ruwa ba. Misali, acidity na 0.1mol/L hydrochloric acid bayani da 0.1mol/L acetic acid bayani shi ma 100mmol/L, amma ƙimar pH ta bambanta. Ƙimar pH na maganin 0.1mol/L hydrochloric acid shine 1, yayin da ƙimar pH na 0.1 mol/L acetic acid bayani shine 2.9.
41. Menene hanyoyin auna ƙimar pH da aka saba amfani da su?
A cikin samarwa na ainihi, don sauri da sauƙi fahimtar canje-canje a cikin ƙimar pH na ruwa mai shiga tsakani, hanya mafi sauƙi ita ce auna shi da takarda gwajin pH. Don ruwa mara launi ba tare da dakatar da ƙazanta ba, ana iya amfani da hanyoyin launi. A halin yanzu, daidaitaccen hanyar ƙasata don auna ƙimar pH na ingancin ruwa ita ce hanyar potentiometric (hanyar lantarki ta gilashin GB 6920-86). Yawanci ba ya shafar launi, turbidity, colloidal abubuwa, oxidants, da rage jamiái. Hakanan zai iya auna pH na ruwa mai tsabta. Hakanan yana iya auna ƙimar pH na ruwan sharar masana'antu gurbatacce zuwa digiri daban-daban. Wannan kuma hanya ce ta ko'ina da ake amfani da ita don auna ƙimar pH a yawancin tsire-tsire masu kula da ruwa.
Ka'idar ma'aunin ma'auni na pH shine samun yuwuwar wutar lantarki mai nuni, wato, ƙimar pH, ta hanyar auna yuwuwar bambance-bambance tsakanin na'urar lantarki ta gilashi da na'urar magana tare da sanannen yuwuwar. Lantarki na tunani gabaɗaya yana amfani da lantarki calomel ko lantarki na Ag-AgCl, tare da lantarki na calomel shine mafi yawan amfani. Jigon pH potentiometer shine amplifier na DC, wanda ke haɓaka yuwuwar da lantarki ke samarwa kuma yana nuna shi akan kan mita a cikin nau'in lambobi ko masu nuni. Potentiometers yawanci ana sanye da na'urar diyya na zafin jiki don gyara tasirin zafin jiki akan na'urorin lantarki.
Ka'idar aiki na mita pH na kan layi da ake amfani da shi a cikin tsire-tsire masu kula da ruwa shine hanya mai ƙarfi, kuma matakan kariya don amfani daidai suke da na mita pH na dakin gwaje-gwaje. Duk da haka, saboda na'urorin da ake amfani da su suna ci gaba da jikewa a cikin ruwa mai daskarewa ko tankunan iska da sauran wuraren da ke dauke da adadi mai yawa na mai ko microorganisms na dogon lokaci, ban da buƙatar pH meter da aka sanye da na'urar tsaftacewa ta atomatik don electrodes, manual. Ana kuma buƙatar tsaftacewa bisa ga yanayin ingancin ruwa da ƙwarewar aiki. Gabaɗaya, pH meter da aka yi amfani da shi a cikin ruwa mai shiga ko tankin iska ana tsaftace shi da hannu sau ɗaya a mako, yayin da mitar pH da aka yi amfani da ita a cikin ruwan ƙazanta ana iya tsaftace ta da hannu sau ɗaya a wata. Don mita pH waɗanda zasu iya auna zafin jiki lokaci guda da ORP da sauran abubuwa, yakamata a kiyaye su kuma a kiyaye su bisa ga ka'idodin amfani da ake buƙata don aikin aunawa.
42. Menene matakan kariya don auna ƙimar pH?
⑴ Yakamata a kiyaye ma'aunin mai ƙarfi da bushewa da ƙura, ana kunna shi akai-akai don kiyayewa, kuma yakamata a kiyaye sashin haɗin gubar na lantarki don hana ɗigon ruwa, ƙura, mai, da sauransu daga shiga. Tabbatar da ƙasa mai kyau lokacin amfani da wutar AC. Matsakaicin ƙarfi masu ɗaukar nauyi waɗanda ke amfani da busassun batura yakamata su maye gurbin batura akai-akai. A lokaci guda kuma, dole ne a daidaita ma'aunin ma'auni akai-akai da sifili don daidaitawa da kiyayewa. Da zarar an yi kuskure da kyau, sifilin sifilin na'urar mai ƙarfi da daidaitawa da masu daidaita matsayi ba za a iya jujjuya su yadda ake so yayin gwajin ba.
⑵ Ruwan da aka yi amfani da shi don shirya madaidaicin bayani na buffer da kuma wanke lantarki ba dole ba ne ya ƙunshi CO2, yana da darajar pH tsakanin 6.7 da 7.3, da ƙaddamarwa na ƙasa da 2 μs / cm. Ruwan da aka yi da anion da resin musayar cation na iya biyan wannan buƙatu bayan an tafasa kuma a bar shi ya huce. Ya kamata a rufe daidaitaccen buffer ɗin da aka shirya shi kuma a adana shi a cikin kwalban gilashi mai wuya ko kwalban polyethylene, sannan a adana shi a cikin firiji a 4oC don tsawaita rayuwar sabis. Idan an adana shi a cikin iska ko a zazzabi na ɗaki, rayuwar sabis gabaɗaya ba za ta iya wuce watanni 1 ba, ba za a iya mayar da buffer ɗin da aka yi amfani da shi zuwa kwalbar ajiya don sake amfani ba.
⑶ Kafin aunawa na yau da kullun, da farko bincika ko kayan aiki, lantarki, da madaidaicin buffer na al'ada ne. Kuma pH mita ya kamata a calibrated akai-akai. Yawancin lokaci zagayowar daidaitawa shine kwata ɗaya ko rabin shekara, kuma ana amfani da hanyar daidaita maki biyu don daidaitawa. Wato, bisa ga kewayon ƙimar pH na samfurin da za a gwada, an zaɓi daidaitattun hanyoyin buffer guda biyu waɗanda ke kusa da shi. Gabaɗaya, bambancin ƙimar pH tsakanin hanyoyin buffer biyu dole ne ya zama aƙalla mafi girma fiye da 2. Bayan sanyawa tare da bayani na farko, sake gwada bayani na biyu. Bambanci tsakanin sakamakon nuni na potentiometer da daidaitaccen ƙimar pH na daidaitaccen buffer na biyu bai kamata ya fi naúrar pH 0.1 ba. Idan kuskuren ya fi naúrar pH 0.1, yakamata a yi amfani da madaidaicin buffer na uku don gwaji. Idan kuskuren ya kasance ƙasa da raka'a pH 0.1 a wannan lokacin, akwai yuwuwar samun matsala tare da maganin buffer na biyu. Idan har yanzu kuskuren ya fi naúrar pH 0.1, akwai wani abu da ba daidai ba tare da lantarki kuma ana buƙatar sarrafa wutar lantarki ko maye gurbin da sabo.
⑷Lokacin da za a maye gurbin madaidaicin buffer ko samfurin, electrode ya kamata a wanke shi da ruwa mai tsafta, kuma ruwan da ke makale da lantarki ya kamata a shafe shi da takarda mai tacewa, sannan a wanke tare da maganin da za a auna don kawar da tasirin juna. Wannan yana da mahimmanci don amfani da ƙananan buffers. Wannan yana da mahimmanci musamman lokacin amfani da mafita. Lokacin auna ƙimar pH, maganin ruwa ya kamata a motsa shi yadda ya kamata don sanya maganin zama iri ɗaya kuma a sami daidaiton electrochemical. Lokacin karantawa, yakamata a dakatar da motsawar kuma a bar shi ya tsaya na ɗan lokaci don ba da damar karatun ya daidaita.
⑸ Lokacin da ake aunawa, da farko sai a wanke electrodes biyu a hankali da ruwa, sannan a kurkure da samfurin ruwan, sannan a nutsar da electrodes a cikin karamin bakar da ke dauke da samfurin ruwa, girgiza beaker a hankali da hannuwanku don yin samfurin ruwan daidai, kuma rikodin rikodin. Ƙimar pH bayan karatun ya tsaya tsayin daka.
Lokacin aikawa: Oktoba-26-2023
