Feem ntau ntawm cov khoom nyob ib puag ncig peb yog cov sib xyaw ntawm ntau yam tshuaj, yog li kev kawm ntawm lawv cov khoom ua lub luag haujlwm tseem ceeb hauv kev txhim kho chemistry, tshuaj, kev lag luam zaub mov thiab lwm yam kev lag luam. Cov kab lus no tham txog cov teeb meem ntawm qhov kev faib tawm yog dab tsi, thiab nws cuam tshuam li cas rau cov yam ntxwv ntawm qhov system.
Dab tsi yog qhov system disperse?
Ua ntej sib tham txog qib ntawm kev tawg, nws yuav tsum tau qhia meej txog qhov twg lub tswv yim no tuaj yeem siv tau.
Cia peb xav tias peb muaj ob yam khoom sib txawv uas yuav txawv ntawm ib leeg hauv cov tshuaj muaj pes tsawg leeg, piv txwv li, cov ntsev ntsev thiab dej ntshiab, lossis hauv lub xeev ntawm kev sib sau ua ke, piv txwv li, tib cov dej hauv cov kua thiab cov khoom (ice) hais. Tam sim no koj yuav tsum tau noj thiab sib tov ob yam khoom no thiab sib tov kom sib xyaw. Qhov tshwm sim yuav ua li cas? Nws nyob ntawm seb cov tshuaj tiv thaiv puas tshwm sim thaum sib tov los yog tsis. Thaum tham txog dispersed systems, nws yog ntseeg hais tias thaum lawvTsis muaj cov tshuaj tiv thaiv tshwm sim hauv kev tsim, uas yog, cov tshuaj thawj zaug khaws lawv cov qauv ntawm micro theem thiab lawv lub cev muaj zog, xws li qhov ntom, xim, hluav taws xob conductivity, thiab lwm yam.
Yog li, lub tshuab tawg yog qhov sib xyaw ua ke, vim tias ob lossis ntau yam khoom sib xyaw ua ke. Thaum nws tau tsim, cov ntsiab lus ntawm "dispersion nruab nrab" thiab "theem" yog siv. Thawj muaj cov cuab yeej ntawm kev txuas ntxiv nyob rau hauv lub system thiab, raws li txoj cai, pom nyob rau hauv nws nyob rau hauv ib tug loj tus txheeb ze. Qhov thib ob (dispersed theem) yog yam ntxwv ntawm cov khoom ntawm discontinuity, uas yog, nyob rau hauv lub system nws yog nyob rau hauv daim ntawv ntawm cov me me hais, uas yog txwv los ntawm lub nto uas cais lawv los ntawm nruab nrab.
Homogeneous thiab heterogeneous systems
Nws yog qhov tseeb tias ob lub ntsiab lus ntawm cov kab ke sib cais yuav txawv ntawm lawv lub cev. Piv txwv li, yog tias koj muab cov xuab zeb pov rau hauv dej thiab do, nws pom tseeb tias cov nplej ntawm cov xuab zeb uas muaj nyob hauv dej, cov tshuaj formula uas yog SiO2, yuav tsis txawv. nyob rau hauv txhua txoj kev los ntawm lub xeev thaum lawv tsis nyob rau hauv dej. Nyob rau hauv tas li ntawd, ib tug hais txog heterogeneity. Nyob rau hauv lwm yam lus, ib tug heterogeneous system yog ib tug sib tov ntawm ob peb (ob los yog ntau tshaj) theem. Lub tom kawg yog to taub raws li ib co finite ntim ntawm lub system, uas yog yus muaj los ntawm tej yam khoom. Hauv qhov piv txwv saum toj no, peb muaj ob theem: xuab zeb thiab dej.
Txawm li cas los xij, qhov loj ntawm cov khoom ntawm cov theem tawg thaum lawv yaj nyob rau hauv ib qho nruab nrab tuaj yeem ua rau me me uas lawv tsis pom lawv tus kheej cov khoom. Hauv qhov no, ib tug hais txoghomogeneous los yog homogeneous tshuaj. Txawm hais tias lawv muaj ob peb yam, lawv txhua tus tsim ib theem thoob plaws tag nrho cov ntim ntawm qhov system. Ib qho piv txwv ntawm homogeneous system yog kev daws ntawm NaCl hauv dej. Thaum nws yaj, vim muaj kev cuam tshuam nrog cov polar molecules H2O, NaCl siv lead ua decomposes rau hauv cais cations (Na+) thiab anions (Cl -). Lawv yog homogeneously tov nrog dej, thiab nws tsis muaj peev xwm nrhiav tau qhov sib cuam tshuam ntawm cov kuab tshuaj thiab cov kuab tshuaj nyob rau hauv xws li ib tug system.
Particle size
Dab tsi yog qhov kev faib tawm? Tus nqi no yuav tsum tau txiav txim siab ntau ntxiv. Nws sawv cev li cas? Nws yog inversely proportional rau particle loj ntawm lub dispersed theem. Nws yog tus yam ntxwv no uas qhia txog kev faib tawm ntawm txhua yam khoom raws li kev xav.
Thaum kawm disperse systems, cov tub ntxhais kawm feem ntau tsis meej pem hauv lawv cov npe, vim lawv ntseeg tias lawv cov kev faib tawm kuj yog raws li lub xeev ntawm kev sib sau. Qhov no tsis muaj tseeb. Kev sib xyaw ntawm ntau lub xeev ntawm kev sib sau ua ke yeej muaj lub npe sib txawv, piv txwv li, emulsions yog cov khoom siv dej, thiab aerosols twb qhia tias muaj cov roj theem. Txawm li cas los xij, cov khoom ntawm cov tshuab tawg yog nyob ntawm qhov loj me ntawm cov theem yaj hauv lawv.
Kev lees paub dav dav
Kev faib tawm ntawm cov tshuab tawg raws li qib ntawm kev tawg yog muab hauv qab no:
- Yog tias qhov loj me me me me dua 1 nm, ces cov tshuab no hu ua tiag, lossis cov kev daws teeb meem tiag.
- Yog tias qhov loj me me nyob nruab nrab ntawm 1 nm thiab100 nm, ces cov khoom nyob rau hauv nqe lus nug yuav raug hu ua ib tug colloidal tov.
- Yog hais tias cov khoom loj dua 100 nm, ces peb tab tom tham txog kev ncua lossis kev ncua.
Hais txog cov kev faib tawm saum toj no, cia peb qhia ob lub ntsiab lus: ua ntej, cov duab muab tau qhia, uas yog, qhov system uas qhov loj me yog 3 nm tsis tas yuav yog colloid, nws kuj tuaj yeem yog qhov tseeb. daws. Qhov no tuaj yeem tsim los ntawm kev kawm txog nws lub cev. Qhov thib ob, koj tuaj yeem pom tias daim ntawv teev npe siv cov kab lus "qhov loj me". Qhov no yog vim lub fact tias cov duab ntawm cov hais nyob rau hauv lub system yuav ua tau kiag li arbitrary, thiab nyob rau hauv cov ntaub ntawv ntawm ib tug complex geometry. Yog li ntawd, lawv hais txog qee qhov nruab nrab (qhov xwm txheej) ntawm lawv.
Tom qab hauv kab lus peb yuav muab cov lus piav qhia luv luv ntawm cov ntawv sau tseg ntawm cov tshuab tawg.
Cov ntsiab lus tseeb
Raws li tau hais los saum toj no, qib ntawm kev tawg ntawm cov khoom hauv cov kev daws teeb meem tiag tiag yog siab heev (lawv qhov loj me me, < 1 nm) uas tsis muaj qhov cuam tshuam ntawm lawv thiab hnyav (nruab nrab), uas yog, muaj yog ib-theem homogeneous system. Rau kev ua tiav ntawm cov ntaub ntawv, peb nco qab tias qhov loj ntawm lub atom yog nyob ntawm qhov kev txiav txim ntawm ib qho angstrom (0.1 nm). Tus lej kawg qhia tias cov khoom hauv cov kev daws teeb meem tiag tiag yog atomic loj.
Lub luag haujlwm tseem ceeb ntawm cov kev daws teeb meem tseeb uas paub qhov txawv ntawm cov colloids thiab kev ncua yog raws li hauv qab no:
- Lub xeev ntawm kev daws teeb meem tshwm sim rau lub sijhawm ntev tsis hloov pauv, uas yog, tsis muaj nag lossis daus ntawm cov txheej txheem tawg.
- Txhob Cia SiabCov khoom tsis tuaj yeem raug cais tawm ntawm cov kuab tshuaj los ntawm kev pom los ntawm daim ntawv dawb.
- Cov tshuaj no kuj tsis sib cais vim yog cov txheej txheem ntawm kev nkag mus rau hauv daim nyias nyias, uas yog hu ua dialysis hauv chemistry.
- Nws tuaj yeem cais cov kuab tshuaj los ntawm cov kuab tshuaj tsuas yog hloov lub xeev ntawm kev sib sau ua ke tom kawg, piv txwv li, los ntawm evaporation.
- Rau cov kev daws teeb meem zoo tshaj plaws, electrolysis tuaj yeem ua tau, uas yog, hluav taws xob tuaj yeem dhau mus yog tias muaj qhov sib txawv (ob lub tshuab hluav taws xob) siv rau lub cev.
- Lawv tsis tawg lub teeb.
Ib qho piv txwv ntawm cov kev daws teeb meem yog kev sib xyaw ntawm ntau cov ntsev nrog dej, piv txwv li, NaCl (lub rooj ntsev), NaHCO 3 (baking soda), KNO 3(potassium nitrate) thiab lwm yam.
Colloid daws
Cov no yog cov nruab nrab nruab nrab ntawm cov kev daws teeb meem tiag tiag thiab kev tshem tawm. Txawm li cas los xij, lawv muaj ntau yam tshwj xeeb. Cia peb sau lawv:
- Lawv yog cov neeg kho tshuab ruaj khov rau lub sijhawm ntev yog tias cov xwm txheej ib puag ncig tsis hloov. Nws txaus los ua kom sov lub cev lossis hloov nws cov kua qaub (pH nqi), raws li cov colloid coagulates (precipitates).
- Lawv tsis sib cais siv cov ntawv lim, txawm li cas los xij, cov txheej txheem lim ntshav ua rau kev sib cais ntawm cov theem dispersed thiab nruab nrab.
- Raws li cov kev daws teeb meem tiag tiag, lawv tuaj yeem raug electrolyzed.
- Rau pob tshab colloidal systems, lub npe hu ua Tyndall effect yog yam ntxwv: hla lub teeb ntawm lub teeb los ntawm qhov system no, koj tuaj yeem pom nws. Nws txuas nrogtawg ntawm electromagnetic nthwv dej nyob rau hauv qhov pom ib feem ntawm lub spectrum nyob rau hauv tag nrho cov lus qhia.
- Muaj peev xwm adsorb lwm yam tshuaj.
Colloidal systems, vim yog cov khoom teev tseg, tau siv dav los ntawm tib neeg hauv ntau yam haujlwm (kev lag luam zaub mov, chemistry), thiab feem ntau pom muaj nyob hauv cov xwm txheej. Ib qho piv txwv ntawm ib tug colloid yog butter, mayonnaise. Hauv qhov xwm txheej, cov no yog huab, huab.
Ua ntej yuav mus rau qhov kev piav qhia ntawm lub xeem (thib peb) chav kawm ntawm disperse systems, cia peb piav qhia ntau ntxiv txog qee yam khoom muaj npe rau colloids.
Cov tshuaj colloidal yog dab tsi?
Rau hom kev faib tawm no, kev faib tawm tuaj yeem muab tau, suav nrog ntau lub xeev sib txawv ntawm qhov nruab nrab thiab theem yaj hauv nws. Hauv qab no yog lub rooj sib tham /
| Wednesday/Phase | Gas | kua | Lub cev tsis muaj zog |
| gas | tag nrho cov pa roj yog infinitely soluble nyob rau hauv ib leeg, yog li lawv ib txwm tsim cov ntsiab lus tseeb | aerosol (fog, huab) | aerosol (smog) |
| kua | ua npuas ncauj (shaving, whipped cream) | emulsion (mis nyuj, mayonnaise, ntses) | sol (watercolors) |
| lub cev khov kho | ua npuas ncauj (pumice, aerated chocolate) | sol (ruby crystal, granite) |
Lub rooj qhia tau hais tias cov tshuaj colloidal muaj nyob txhua qhov chaw, ob qho tib si hauv lub neej txhua hnub thiab hauv qhov xwm txheej. Nco ntsoov tias lub rooj zoo sib xws kuj tuaj yeem muab rau kev ncua, nco ntsoov tias qhov sib txawv nrogcolloids nyob rau hauv lawv tsuas yog nyob rau hauv qhov loj ntawm lub dispersed theem. Txawm li cas los xij, kev ncua yog qhov tsis ruaj khov thiab yog li ntawd tsis tshua muaj txiaj ntsig zoo dua li cov tshuab colloidal.
Yog vim li cas rau cov neeg kho tshuab ruaj khov ntawm colloids
Vim li cas mayonnaise tuaj yeem pw hauv lub tub yees ntev ntev, thiab cov khoom raug tshem tawm hauv nws tsis tuaj yeem nag lossis daus? Vim li cas ho tsis pleev xim rau hauv dej thaum kawg "poob" mus rau hauv qab ntawm lub nkoj? Cov lus teb rau cov lus nug no yuav yog Brownian tsab ntawv tsa suab.
hom kev txav no tau pom nyob rau hauv thawj ib nrab ntawm lub xyoo pua 19th los ntawm Askiv botanist Robert Brown, uas tau soj ntsuam hauv lub tshuab ntsuas seb cov paj ntoos me me txav hauv dej. Los ntawm qhov pom ntawm lub cev, Brownian cov lus tsa suab yog ib qho kev tshwm sim ntawm chaotic txav ntawm cov kua molecules. Nws qhov kev siv zog nce ntxiv yog tias qhov kub ntawm cov kua tau nce. Nws yog hom kev txav no uas ua rau me me ntawm cov tshuaj colloidal nyob rau hauv kev ncua.
Adsorption khoom
Dispersity yog qhov sib txuam ntawm qhov nruab nrab particle loj. Txij li qhov loj me no hauv colloids nyob rau hauv thaj tsam ntawm 1 nm mus rau 100 nm, lawv muaj qhov tsim tau zoo heev, uas yog, qhov sib piv S / m yog tus nqi loj, ntawm no S yog tag nrho cov cheeb tsam cuam tshuam ntawm ob theem (dispersion nruab nrab. thiab hais), m - tag nrho cov huab hwm coj ntawm cov khoom hauv cov tshuaj.
Atoms uas nyob rau saum npoo ntawm cov khoom ntawm cov theem dispersed muaj unsaturated chemical bonds. Qhov no txhais tau tias lawv tuaj yeem tsim cov tebchaw nrog lwm tusmolecules. Raws li txoj cai, cov tebchaw no tshwm sim vim yog van der Waals rog lossis hydrogen bonds. Lawv muaj peev xwm tuav tau ob peb txheej ntawm molecules ntawm qhov chaw ntawm colloidal hais.
Ib qho piv txwv classic ntawm ib qho adsorbent yog activated carbon. Nws yog ib qho colloid, qhov nruab nrab dispersion yog ib qho khoom, thiab theem yog roj. Qhov chaw tshwj xeeb rau nws tuaj yeem ncav cuag 2500 m2/g.
Degree ntawm fineness thiab thaj chaw tshwj xeeb
Xaiv S/m tsis yog ib txoj haujlwm yooj yim. Qhov tseeb yog tias cov khoom hauv cov tshuaj colloidal muaj qhov sib txawv, cov duab, thiab qhov chaw ntawm txhua qhov muaj qhov tshwj xeeb nyem. Yog li ntawd, cov txheej txheem theoretical los daws qhov teeb meem no ua rau muaj txiaj ntsig zoo, thiab tsis yog qhov ntau. Txawm li cas los xij, nws yog qhov tseem ceeb los muab cov qauv rau thaj chaw tshwj xeeb los ntawm qib ntawm dispersion.
Yog tias peb xav tias tag nrho cov khoom ntawm lub cev muaj cov duab kheej kheej thiab qhov loj me, tom qab ntawd los ntawm kev suav ncaj nraim, cov lus qhia hauv qab no tau txais: Sud=6/(dρ), qhov twg Sud - thaj chaw (specific), d - particle inch, ρ - ntom ntawm cov khoom uas nws muaj. Nws tuaj yeem pom los ntawm cov qauv uas cov khoom me me thiab hnyav tshaj plaws yuav ua rau feem ntau ntawm cov khoom raws li kev txiav txim siab.
Txoj kev sim los txiav txim siab Sud yog los xam qhov ntim ntawm cov pa uas yog adsorbed los ntawm cov khoom nyob rau hauv kev kawm, nrog rau ntsuas qhov pore loj (qib tawg) hauv nws.
Nyob qhuav qhuav thiablyophobic
Lyophilicity thiab lyophobicity - cov no yog cov yam ntxwv uas, qhov tseeb, txiav txim siab qhov muaj nyob ntawm kev faib tawm ntawm cov kab ke sib cais hauv daim ntawv uas tau muab los saum toj no. Ob lub tswv yim qhia lub zog sib txuas ntawm cov molecules ntawm cov kuab tshuaj thiab cov kuab tshuaj. Yog tias qhov kev sib raug zoo no loj, ces lawv hais txog lyophilicity. Yog li, tag nrho cov kev daws teeb meem tseeb ntawm cov ntsev hauv dej yog lyophilic, vim lawv cov khoom (ions) yog hluav taws xob txuas nrog cov polar molecules H 2 O. Yog tias peb xav txog cov tshuab xws li butter lossis mayonnaise, cov no yog cov neeg sawv cev ntawm cov hydrophobic colloids, txij li cov roj (lipid) molecules nyob rau hauv lawv tawm tsam polar molecules H2 O.
Nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov tias lyophobic (hydrophobic yog cov kuab tshuaj yog dej) cov tshuab yog cov thermodynamically tsis ruaj khov, uas txawv ntawm cov lyophobic.
Txoj kev tshem tawm
Tam sim no xav txog cov chav kawm kawg ntawm kev sib cais - kev ncua. Nco qab tias lawv yog tus cwj pwm los ntawm qhov tseeb tias qhov me me hauv lawv yog qhov loj dua lossis ntawm qhov kev txiav txim ntawm 100 nm. Lawv muaj dab tsi? Cov npe sib raug tau muab hauv qab no:
- Lawv tsis ruaj khov, yog li lawv tsim cov av hauv lub sijhawm luv luv.
- Lawv pos huab thiab opaque rau tshav ntuj.
- Phase tuaj yeem sib cais los ntawm nruab nrab nrog cov ntawv lim.
Piv txwv ntawm kev ncua hauv qhov xwm txheej suav nrog cov av nkos hauv cov dej ntws los yog cov tshauv volcanic. Tib neeg siv cov kev ncua yog txuam nrogfeem ntau yog nrog tshuaj (drug solutions).
Dab tsi tuaj yeem hais txog kev sib xyaw ntawm cov khoom sib txawv ntawm qhov sib txawv? Ib feem, qhov teeb meem no twb tau hais nyob rau hauv tsab xov xwm, txij li thaum nyob rau hauv ib tug disperse system cov hais muaj ib tug loj uas nyob rau hauv tej yam kev txwv. Ntawm no peb tsuas yog xav txog ib rooj plaub xav paub. Yuav ua li cas yog tias koj sib tov ib qho colloid thiab cov tshuaj electrolyte tiag? Lub cev hnyav yuav tawg, thiab nws cov coagulation yuav tshwm sim. Nws yog vim li cas nyob rau hauv lub zog ntawm hluav taws xob teb ntawm qhov tseeb tov ions nyob rau saum npoo ntawm tus nqi ntawm colloidal hais.
