chemical hourglass

Cov tshuaj tiv thaiv ib teev yog cov kev hloov pauv uas nws cov txiaj ntsig (piv txwv li, kev hloov xim) tsis tshwm sim tam sim ntawd, tab sis tsuas yog tom qab qee lub sij hawm tom qab sib tov cov reagents. Tseem muaj cov tshuaj tiv thaiv uas tso cai rau koj pom qhov tshwm sim ob peb zaug. Los ntawm kev sib piv nrog "tshuaj tshuaj" lawv tuaj yeem hu ua "chemical hourglass". Reagents rau ib qho kev sim tsis yooj yim nrhiav.

Rau kev kuaj peb yuav siv magnesium oxide, MgO, 3-4% hydrochloric acid, HCl_aq (concentrated acid, diluted nrog dej 1: 9) los yog zaub mov vinegar (6-10% tov ntawm acetic acid CH₃COV). Yog tias peb tsis muaj magnesium oxide, cov tshuaj tiv thaiv acidity thiab kub siab yuav ua tiav nws - ib qho ntawm cov khoom xyaw yog magnesium hydroxide (MgO hloov mus rau hauv cov tshuaj no hauv cov tshuaj tiv thaiv).

Lub luag haujlwm rau kev hloov xim thaum lub sijhawm cov tshuaj tiv thaiv bromthymol xiav - qhov taw qhia hloov daj hauv cov kua qaub thiab yuav luag xiav.

Rau iav 100 cm³ ncuav 1-2 teaspoons ntawm magnesium oxide (duab 1) los yog ncuav txog 10 cm³ kev npaj muaj magnesium hydroxide. Tom qab ntawd ntxiv 20-30 cm.³ dej (duab 2) thiab ntxiv ob peb tee ntawm qhov ntsuas (duab 3). Sib tov cov ntsiab lus ntawm cov xim xiav xiav (duab 4) thiab tom qab ntawd ncuav ob peb cm³ kua qaub (duab 5). Cov sib tov nyob rau hauv lub khob tig daj (duab 6), tab sis tom qab ib pliag nws tig xiav dua (duab 7). Ntxiv lwm feem ntawm cov kua qaub, peb rov soj ntsuam cov xim hloov (siv 8i9). Lub voj voog tuaj yeem rov ua dua ob peb zaug.

Cov nram qab no tshwm sim tshwm sim nyob rau hauv lub beaker:

1. Magnesium oxide reacts nrog dej los tsim cov hydroxide ntawm cov hlau no:

MgO + N₂O → Mg(OH)₂

Cov txiaj ntsig tau tshwm sim tsis zoo hauv dej (li 0,01 g ib 1 dm³), tab sis nws yog ib lub hauv paus muaj zog thiab cov concentration ntawm hydroxide ions yog txaus rau xim qhov taw qhia.

2. Cov tshuaj tiv thaiv ntawm magnesium hydroxide nrog ntxiv ntawm hydrochloric acid:

mg (OH)₂ 2 HCl → MgCl₂ + 2 hli₂O

ua rau cov neutralization ntawm tag nrho Mg (OH) yaj hauv dej₂. Tshaj HCl_aq hloov ib puag ncig rau acidic, uas peb tuaj yeem pom los ntawm kev hloov xim ntawm qhov ntsuas mus rau daj.

3. Lwm qhov ntawm magnesium oxide reacts nrog dej (kev sib npaug 1.thiab neutralizes cov kua qaub ntau dhau (kev sib npaug 2.). Cov tshuaj ua alkaline dua thiab qhov taw qhia tig xiav. Lub voj voog rov ua dua.

Kev hloov kho yog hloov qhov ntsuas tau siv, uas ua rau muaj xim sib txawv. Hauv kev sim thib ob, tsis yog bromthymol xiav, peb yuav siv phenolphthalein (tsis muaj xim hauv cov kua qaub, raspberry hauv cov tshuaj alkaline). Peb npaj ib qho kev ncua ntawm magnesium oxide nyob rau hauv dej (lub thiaj li hu ua mis nyuj ntawm magnesia), raws li nyob rau hauv lub yav dhau los sim. Ntxiv ob peb tee ntawm cov tshuaj phenolphthalein (duab 10) thiab do cov ntsiab lus ntawm iav. Tom qab ntxiv ob peb³ hydrochloric acid (duab 11) qhov sib tov ua tsis muaj xim (duab 12). stirring cov ntsiab lus txhua lub sijhawm, koj tuaj yeem hloov pauv: kev hloov xim rau xim liab, thiab tom qab ntxiv ib feem ntawm cov kua qaub, kev hloov pauv ntawm cov ntsiab lus ntawm lub nkoj (duab 13, 14, 15).

Cov tshuaj tiv thaiv ua haujlwm zoo ib yam li hauv thawj qhov kev sim. Ntawm qhov tod tes, siv qhov ntsuas sib txawv ua rau muaj xim sib txawv. Yuav luag txhua qhov ntsuas pH tuaj yeem siv rau hauv qhov kev sim.

Chemical Hourglass Part I:

Tshuaj Hourglass Part I

Chemical Hourglass Part II:

Tshuaj Hourglass Part XNUMX