mass vs Molar Mass
Peb paub txog huab hwm coj txawm hais tias peb feem ntau siv lub tswv yim ntawm qhov hnyav es tsis txhob hnyav hauv peb lub neej txhua hnub. Qhov hnyav ntawm tus neeg yog ib qho khoom ntawm qhov loj ntawm nws lub cev thiab lub ntiajteb txawj nqus. Txij li cov nyhuv gravitational no zoo ib yam thoob ntiaj teb, nws yooj yim dua los tham txog qhov hnyav. Tab sis thaum peb tham txog cov khoom me me xws li molecules thiab atoms ntawm cov khoom, cov ntsiab lus ntawm molecular mass thiab molar mass yog siv. Muaj qhov sib txawv ntawm qhov loj thiab molar loj ntawm cov khoom uas yuav pom meej tom qab nyeem tsab xov xwm no.
Hauv txoj kev xav, qhov loj ntawm ib yam khoom yog nws qhov sib txheeb loj raws li nws tau qhia nyob rau hauv cov ntsiab lus ntawm cov pa roj carbon atom uas tau muab coj los ua 12. Hauv kev xyaum, txawm li cas los xij, qhov molecular loj ntawm ib yam khoom raug coj los ua qhov sib npaug ntawm atomic masses ntawm cov khoom siv atoms ntawm cov molecule. Piv txwv li, yog tias peb yuav tsum xam cov molecular loj ntawm carbon monoxide peb yuav tsum ntxiv cov atomic masses ntawm carbon thiab hydrogen. Raws li atomic mass ntawm carbon yog 12 thiab cov pa oxygen yog 16, molecular loj ntawm carbon monoxide yog 12 + 16=28. Ib yam li ntawd, yog tias cov khoom yog carbon dioxide, peb paub tias muaj ob lub atoms ntawm oxygen koom nrog, yog li cov molecular loj ntawm CO2 yuav raug xam raws li nram no: 12 + 16 × 2=44
Molecular mass yog tus lej tsis muaj qhov ntev.
Qhov hnyav hauv grams ntawm ib lub mole ntawm ib yam khoom hu ua nws molar mass. Cov khoom sib txawv muaj cov molar sib txawv, thiab qhov no yog vim cov atoms ntawm cov ntsiab lus sib txawv muaj cov electrons, protons thiab neutrons sib txawv. Ib qho mole ntawm cov khoom muaj 6.022 x 1023 atoms ntawm cov khoom ntawd. Qhov no tseem hu ua Avogadro tus lej. Lub molar loj ntawm carbon yog 12.011g thaum cov magnesium yog 24.3050g.
Tab sis thaum nws los txog rau molar mass ntawm cov tebchaw, thawj kauj ruam yog los xam nws cov molecular mass, uas yog cov sum ntawm atomic masses ntawm lub constituent ntsiab. Cia peb ua piv txwv dej.
Molecular mass of water=2 x 1.00794 (atomic mass of hydrogen) + 15.9994 (atomic mass of oxygen)=18.0153
Molar mass of a molecular compound=molecular mass in grams/ 1 mole compound
Yog li cov molar loj ntawm dej=18.0153 / 1 mole ntawm H2O
Qhov Sib Txawv Ntawm Pawg thiab Molar Mass
• Mass, los yog molecular mass ntawm ib yam khoom yog qhov loj ntawm ib lub molecule ntawm cov khoom thiab yog cov sum ntawm cov atomic masses ntawm cov constituent ntsiab
• Molar mass yog qhov hnyav hauv grams ntawm ib lub mole ntawm ib yam khoom uas yog tus naj npawb ntawm atoms hauv ib mole ntawm cov khoom. Nws yog tus lej tas li hu ua Avogadro tus lej.
• Thaum molecular mass yog ib tug dimensionless tus naj npawb uas qhia txog qhov loj ntawm carbon atom, molar mass yog qhia nyob rau hauv grams
• Ntau tus xav tias ob nqe lus yog tib yam tab sis hauv kev xyaum, qhov nruab nrab huab cua tsis zoo ib yam li qhov loj ntawm ib lub molecule
• Thaum txiav txim siab me me, qhov sib txawv me me thiab ob qhov sib npaug sib npaug
