Tsis ntsiab: kev npaj thiab kev siv

Buffers - nws daws teeb meem uas muaj buffering system. Tsis systems hu ua sib tov nyob rau hauv uas muaj pes tsawg leeg muaj qee ntau piv tsis muaj zog acids thiab lawv ntsev nrog muaj zog bases los yog tsis muaj zog bases thiab lawv ntsev nrog muaj zog acids. Tej kev daws teeb meem muaj ib tug ruaj khov concentration ntawm H + ions ntawm nruab nrab diluting hnyav (dej) thiab ntxiv rau lawv ib qhov nqi ntawm muaj zog acids los yog bases.

Tsis ntsiab tseem nyob rau hauv qhov dej ntawm tus dej hiav txwv, av daws thiab nyob rau hauv uas muaj sia nyob. Cov systems khiav lag luam lwm yam uas zog uas txhawb active tshuaj tiv thaiv nruab nrab ntawm ib lub nqi tsim nyog rau kev vam meej tshwm sim ntawm metabolic tshua. Tsis ntsiab yog txwv kom muab zais rau hauv acidic thiab yooj yim. Ib qho piv txwv muaj peev xwm ua ntej yuav acetate tsis system, lub thib ob - ammonium. Paub qhov txawv tej yam ntuj tso thiab dag buffers. Ib tug tej yam ntuj tso tsis daws yog ntshav muaj hydrocarbonate, phosphate, protein, hemoglobin thiab ib tug acidic tsis system. Dag tsis tej zaum yuav acetate tsis, muaj raws ntawm CH3COOH.

Nta ntawm Internal qauv thiab mechanism ntawm qhov kev txiav txim ntawm tus tsis systems peb xav txog cov piv txwv ntawm ib tug acetate tsis system: acetate acid / sodium acetate. Nyob rau hauv lub aqueous nruab nrab ib tug tsis system Cheebtsam yog raug electrolytic dissociation. Sodium acetate raws li lub ntsev ntawm ib tug tsis muaj zog acid thiab ib tug muaj zog puag kiag dissociates rau hauv ions. Lub xub ntiag ntawm anions nyob rau hauv ib tug tsis sib tov nyob rau hauv lub concentration ntawm ntsev nyob rau ntawd thiab nws cov degree ntawm dissociation. Lub concentration ntawm H + ions nyob rau hauv lub tsis system yog ncaj qha xwm yeem mus rau concentration ntawm acid nyob rau hauv nws thiab inversely xwm yeem mus rau nws cov ntsiab lus ntawm cov ntsev ntawm no acid.

Yog li, lub concentration ntawm H + ions nyob rau hauv lub yooj yim tsis yog ncaj qha xwm yeem mus rau concentration ntawm ntsev nyob rau hauv nws thiab inversely xwm yeem mus rau concentration ntawm ib lub hauv paus.

Nyob rau hauv laboratory xyaum, siv tsis daws teeb meem nrog paub qhov tseem ceeb ntawm pH. Yog li, qhov kev npaj ntawm tsis daws teeb meem yog nqa tawm los ntawm kev siv cov ntsiab ntawm ib tug tsis muaj zog acid thiab nws ntsev nrog ib tug muaj zog puag los yog tsis muaj zog los luj thiab nws ntsev nrog ib tug muaj zog acid. Ces los hloov tus quantitative piv ntawm lub Cheebtsam, tsis daws teeb meem manufactured nrog lub setpoint pH. Ib txhia xav li cas rau hauv kev npaj ntawm cov tshuaj.

Piv txwv li, nws yog tsim nyog los npaj ib tug acetate tsis nyob rau ntau qhov tseem ceeb ntawm pH. Chiv npaj 5M tshuaj ntawm acetate acid thiab sodium acetate. Rau qhov kev npaj ntawm cov thawj cov tshuaj noj 50 ml ntawm txhua tus ntawm lub Cheebtsam. Coj los ntawm cov mis, lub concentration ntawm H + ions nyob rau hauv lub resulting tov.

Rau tom ntej no tsis tshuaj noj 80 ml ntawm cov acid tov thiab 20 ml ntawm ntsev tov npaj yav tas los. Muaj ib tug xov tooj ntawm formulations ntawm ntau yam tsis daws teeb meem siv nyob rau hauv cov tshuaj tsom xam thiab kuaj xyaum.

Rau ib tug raug buffers zog. Rau cov neeg feem koom buffering - muaj peev xwm tswj tau lub constancy ntawm lub concentration ntawm H + ions thaum ntxiv nyob rau hauv ib qhov nqi uas tsis tshuaj ntawm ib tug muaj zog acid los yog ib tug muaj zog paus. Piv txwv li, yog ib tug acetate tsis ntxiv ib tug me me npaum li cas ntawm acid chloride, pH hloov mus rau acid sab tsis tshwm sim, txij thaum lub acid chloride yuav hnov mob pauv decomposition nrog ib lub ntsev ntawm ib tug tsis muaj zog acid. Cov tshuaj tiv thaiv ntawm ib tug muaj zog acid muaj peev xwm khiav tawm lub pH mus rau lub acid sab, thiab hloov los ntawm ib tug nruab nrab tsis muaj zog acid ntsev. Lub degree ntawm dissociation ntawm ib tug tsis muaj zog ntsha tov nrog ua concentration txo rau zero, thiab cov pH hloov tshwm sim.