Qhov sib txawv tseem ceeb ntawm qhov kawg thiab stoichiometric taw tes yog qhov kawg ntawm qhov kawg tuaj tom qab qhov taw tes stoichiometric, qhov stoichiometric taw tes yog qhov tseeb tshaj plaws ntawm qhov nruab nrab ntawm kev ua tiav.
Ib acid-base titration muaj cov tshuaj tiv thaiv neutralization, uas tshwm sim ntawm qhov chaw uas cov kua qaub reacts nrog cov tshuaj sib npaug ntawm lub hauv paus. Txawm li cas los xij, muaj qhov sib txawv me ntsis ntawm qhov taw tes theoretical qhov twg cov tshuaj tiv thaiv raws nraim xaus thiab qhov chaw uas peb pom nws xyaum. Ntxiv mus, koj yuav tsum nco ntsoov tias lo lus sib npaug taw tes yog ib lub npe siv ntau dua rau stoichiometric point.
Endpoint yog dab tsi?
Lub ntsiab lus ntawm qhov kev tawm tsam zoo li ua tiav yog qhov kawg ntawm qhov kev sib tw. Peb tuaj yeem sim txiav txim siab qhov no. Cia peb xav txog ib qho piv txwv kom to taub qhov no. Xav tias peb titrate 100 ml ntawm 0.1 M hydrochloric acid (HCl) nrog 0.5 M sodium hydroxide.
HCl(aq) + NaOH(aq) ⟶ H2O + NaCl (aq)
Peb khaws cov kua qaub rau hauv lub khob titration thiab titrating tawm tsam NaOH nyob rau hauv muaj cov methyl txiv kab ntxwv raws li qhov taw qhia. Hauv nruab nrab acidic, qhov taw qhia tsis muaj xim thiab nws pom cov xim liab hauv nruab nrab nruab nrab. Thaum pib, tsuas muaj kua qaub (HCl 0.1 M / 100 ml) nyob rau hauv lub hwj titration; pH ntawm cov tshuaj yog sib npaug rau 2. Raws li peb ntxiv NaOH, pH ntawm cov tshuaj nce vim qhov nruab nrab ntawm qee cov kua qaub hauv nruab nrab. Peb yuav tsum ntxiv lub hauv paus tsis tu ncua los ntawm kev poob kom txog thaum nws tiav. Lub pH ntawm cov tshuaj tiv thaiv yuav sib npaug rau 7 thaum cov tshuaj tiv thaiv tiav. Txawm nyob rau ntawm no, qhov taw qhia qhia tsis muaj xim nyob rau hauv nruab nrab vim nws hloov xim nyob rau hauv nruab nrab nruab nrab.
Txhawm rau soj ntsuam cov xim hloov, peb yuav tsum tau ntxiv ib qho ntxiv ntawm NaOH, txawm tias tom qab ua tiav qhov nruab nrab. Lub pH ntawm cov tshuaj hloov pauv hloov ntawm lub sijhawm no. Qhov no yog lub ntsiab lus uas peb soj ntsuam raws li cov tshuaj tiv thaiv tiav.
Stoichiometric Point yog dab tsi?
Qhov sib npaug yog lub npe nrov rau stoichiometric point. Nws yog lub ntsiab lus ntawm cov kua qaub lossis lub hauv paus ua tiav nws cov tshuaj tiv thaiv neutralization. Ib qho tshuaj tiv thaiv tau ua tiav theoretically ntawm lub sijhawm no, tab sis kev xyaum peb tsis tuaj yeem soj ntsuam qhov tseeb. Nws yog qhov zoo dua yog tias peb tuaj yeem txiav txim siab thaum twg qhov sib npaug tau mus txog vim tias nws yog lub ntsiab lus tseeb uas qhov nruab nrab tau tshwm sim. Txawm li cas los xij, peb tuaj yeem soj ntsuam qhov kev ua tiav ntawm qhov kawg.
Daim duab 01: Daim duab rau Titration uas qhia qhov sib npaug Point
Yog tias peb xav txog tib yam piv txwv li saum toj no, thaum pib cov tshuaj tiv thaiv, peb tsuas muaj cov kua qaub hauv nruab nrab (HCl). Ua ntej nws mus txog qhov sib npaug, nrog rau qhov sib ntxiv ntawm NaOH, peb muaj cov kua qaub uas tsis muaj kev cuam tshuam thiab tsim cov ntsev (HCl thiab NaCl). Ntawm qhov sib npaug, peb tsuas muaj ntsev hauv nruab nrab. Thaum kawg, peb muaj ntsev thiab lub hauv paus (NaCl thiab NaOH) hauv nruab nrab.
Qhov txawv ntawm Qhov Kawg thiab Stoichiometric Point yog dab tsi?
Endpoint thiab stoichiometric point (hauv qhov sib npaug, qhov sib npaug) ib txwm sib txawv ntawm ib leeg. Qhov sib txawv tseem ceeb ntawm qhov kawg thiab qhov taw tes stoichiometric yog qhov kawg ntawm qhov kawg tuaj tom qab qhov taw tes stoichiometric, qhov stoichiometric point yog qhov tseeb tshaj plaws uas qhov nruab nrab ua tiav. Tsis tas li ntawd, peb tuaj yeem soj ntsuam qhov kawg tab sis tsis tuaj yeem soj ntsuam qhov taw tes stoichiometric xyaum.
Summary – Endpoint vs Stoichiometric Point
Endpoint thiab stoichiometric point (hauv qhov sib npaug, qhov sib npaug) ib txwm sib txawv ntawm ib leeg. Qhov sib txawv tseem ceeb ntawm qhov kawg thiab qhov taw tes stoichiometric yog qhov kawg ntawm qhov kawg tuaj tom qab qhov taw tes stoichiometric, qhov stoichiometric taw tes yog qhov tseeb tshaj plaws uas qhov nruab nrab ua tiav.
