Dab tsi yog pawg feem hauv chemistry? Koj puas paub cov lus teb? Yuav ua li cas nrhiav tau qhov loj feem ntawm ib lub caij hauv ib yam khoom? Cov txheej txheem suav nws tus kheej tsis yog qhov nyuaj heev. Koj puas tseem muaj teeb meem ua haujlwm zoo li no? Ces hmoov zoo luag ntxhi rau koj, koj pom zaj no! Txaus siab? Tom qab ntawv nyeem, tam sim no koj yuav nkag siab txhua yam.
Dab tsi yog pawg feem ntau?
Yog li ntawd, ua ntej, cia peb kawm seb qhov feem ntau yog dab tsi. Yuav ua li cas thiaj nrhiav tau cov feem loj ntawm cov khoom hauv ib yam khoom, txhua tus kws tshuaj yuav teb, vim lawv feem ntau siv lo lus no thaum daws teeb meem lossis thaum lawv nyob hauv chav kuaj. Tau kawg, vim nws qhov kev suav yog lawv txoj haujlwm txhua hnub. Txhawm rau kom tau txais qee yam ntawm cov khoom tshwj xeeb hauv kev kuaj mob, qhov kev suav tseeb thiab tag nrho cov txiaj ntsig ntawm cov tshuaj tiv thaiv tseem ceeb heev, koj yuav tsum paub ob peb yam yooj yim cov qauv thiab nkag siab txog cov ntsiab lus ntawm cov feem ntau. Vim li no lub ntsiab lus tseem ceeb heev.
lo lus no yog txhais los ntawm lub cim "w" thiab nyeem ua "omega". Nws qhia qhov piv ntawm qhov loj ntawm ib qho muabcov khoom mus rau tag nrho cov loj ntawm ib tug sib tov, tov los yog molecule, qhia raws li ib feem los yog ib tug feem pua. Cov mis loj feem ntau:
w =m substances /m mixtures.
Transform the formula.
Peb paub tias m=nM, qhov twg m yog pawg; n yog tus nqi ntawm cov khoom, qhia nyob rau hauv units ntawm mole; M yog cov molar loj ntawm cov khoom, qhia hauv grams / mol. Cov molecular loj yog tus lej sib npaug rau cov molecular loj. Tsuas yog qhov hnyav molecular yog ntsuas hauv atomic mass units lossis a. e. m. Xws li ib chav ntsuas ntsuas yog sib npaug rau ib tug kaum ob ntawm qhov loj ntawm cov pa roj carbon nucleus 12. Tus nqi ntawm qhov hnyav molecular tuaj yeem pom nyob rau hauv lub sij hawm.
Tus nqi ntawm cov khoom n ntawm cov khoom xav tau hauv cov khoom sib xyaw yog sib npaug rau qhov ntsuas sib npaug los ntawm cov coefficient rau qhov sib xyaw no, uas yog qhov laj thawj heev. Piv txwv li, txhawm rau xam cov naj npawb ntawm cov atoms hauv ib lub molecule, koj yuav tsum nrhiav seb muaj pes tsawg atoms ntawm cov khoom xav tau nyob hauv 1 molecule=Performance index, thiab muab cov lej no los ntawm cov lej ntawm cov molecules=coefficient.
Tsis txhob ntshai ntawm cov ntsiab lus cumbersome lossis cov qauv, lawv taug qab qee qhov laj thawj, nkag siab uas, koj tsis tuaj yeem kawm cov qauv ntawm lawv tus kheej. Cov molar mass M yog sib npaug rau cov lej ntawm cov atomic masses A rntawm cov khoom muab. Nco qab tias atomic mass yog qhov loj ntawm 1 atom ntawm ib yam khoom. Ntawd yog, tus qauv loj feem ntau:
w =(n tshuajM tshuaj)/m mixtures.
Los ntawm qhov no peb tuaj yeem txiav txim siab tias yog qhov sib tov muaj ib yam khoom, cov feem loj ntawm cov uas yuav tsum tau muab xam, ces w=1, vim qhov loj ntawm qhov sib tov thiab qhov loj ntawm cov khoom yog tib yam. Txawm hais tias qhov sib xyaw ua ntej tsis tuaj yeem suav nrog ib qhotshuaj.
Yog li, peb xam qhov kev xav, tab sis yuav ua li cas thiaj nrhiav tau cov feem ntau ntawm cov khoom hauv ib qho kev xyaum? Tam sim no peb yuav qhia thiab qhia txhua yam.
Tshawb xyuas cov ntaub ntawv kawm. Yooj Yim Sib Tw
Tam sim no peb yuav txheeb xyuas ob txoj haujlwm: yooj yim thiab nruab nrab. Nyeem ntxiv!
Nws yog ib qho tsim nyog kom paub seb qhov loj ntawm cov hlau nyob hauv cov molecule ntawm ferrous sulfate FeSO47 H2O. Yuav daws qhov teeb meem no li cas? Xav txog qhov kev daws teeb meem ntxiv.
Kev daws:
Cia 1 mol ntawm FeSO47 H2O, ces nrhiav tus nqi ntawm cov hlau los ntawm kev muab cov coefficient ntawm hlau. los ntawm nws qhov ntsuas: 11=1. Muab 1 mole hlau. Peb pom nws qhov loj hauv qhov teeb meem: los ntawm tus nqi hauv lub rooj zaum, nws tuaj yeem pom tias cov hlau atomic loj yog 56 a.u. e.m.=56g/mol. Hauv qhov no, Ar=M. Yog li ntawd, m hlau \u003d nM \u003d 1 mol56 grams / mol \u003d 56 g.
Tam sim no koj yuav tsum nrhiav qhov loj ntawm tag nrho cov molecule. Nws yog sib npaug rau cov lej ntawm cov khoom pib, uas yog, 7 mol dej thiab 1 mol ntawm ferrous sulfate.
m=(n water M water) + (n ferrous sulfate M hlau sulfate)=(7 mol(12 + 16) gram / mol) + (1 mol(1 mol56 gram / mol + 1 mol32 gram / mol + 4 mol16 grams / mol) u003d 126 + 152 \u003d 278 g.
Nws tseem tsuas yog faib cov hlau loj los ntawm qhov loj ntawm qhov sib xyaw:
w=56g/278g=0.20143885~0.2=20%.
Teb: 20%.
haujlwm theem nrab
Cia peb daws qhov teeb meem nyuaj dua. 34 g ntawm calcium nitrate yog yaj hauv 500 g dej. Koj yuav tsum nrhiav cov feem loj ntawm cov pa oxygen hauv qhov kev daws teeb meem.
Kev txiav txim siab
Yograws li nyob rau hauv kev sib cuam tshuam ntawm Ca(NO3)2 nrog dej, tsuas yog cov txheej txheem sib cais tshwm sim, thiab tsis muaj cov tshuaj tiv thaiv tawm ntawm cov tshuaj, Qhov loj ntawm qhov sib tov yog sib npaug rau qhov sib npaug ntawm qhov loj ntawm nitrate calcium thiab dej.
Peb yuav tsum nrhiav cov feem ntau ntawm cov pa oxygen hauv cov tshuaj. Nco ntsoov tias cov pa oxygen muaj nyob rau hauv cov kuab tshuaj thiab cov kuab tshuaj. Nrhiav tus nqi ntawm cov khoom xav tau hauv dej. Txhawm rau ua qhov no, peb suav cov mole ntawm dej raws li tus qauv n=m/M.
n water=500 g/(12+16) gram/mol=27.7777≈28 mol
Los ntawm cov mis dej H2O peb pom tias cov pa oxygen=cov dej, uas yog, 28 mol.
Tam sim no nrhiav cov pa oxygen hauv yaj Ca(NO3)2. Txhawm rau ua qhov no, peb pom cov khoom ntawm nws tus kheej:
n Ca(NO3)2=34 g/(401+2(14+163)) gram/mol≈0.2 mol.
n Ca(NO3)2 refers to n O as 1 to 6, raws li hauv qab no los ntawm cov qauv sib xyaw. Yog li, n O=0.2 mol6=1.2 mol. Tag nrho cov pa oxygen yog 1.2 mol + 28 mol=29.2 mol
m O=29.2 mol16 gram / mol=467.2 g
m solution=m water + m Ca(NO3)2=500g + 34g=534 g.
Nws tseem tsuas yog suav cov feem loj ntawm cov tshuaj lom neeg hauv cov khoom:
w O=467.2g /534g≈0.87=87%.
Teb: 87%.
Peb cia siab tias peb tau piav qhia meej rau koj yuav ua li cas thiaj nrhiav tau cov feem ntau ntawm cov khoom hauv cov khoom. Lub ntsiab lus no tsis nyuaj yog tias koj nkag siab zoo. xavhmoov zoo thiab kev vam meej nyob rau hauv koj lub neej yav tom ntej endeavors.
