Qhov Tseem Ceeb Qhov txawv - Formula Mass vs Molar Mass
Formula mass thiab molar mass yog ob lub cev ntawm cov molecules uas qhia qee qhov sib txawv ntawm lawv. Ob qho ntawm cov kev txwv no, cov mis loj thiab molar loj, muaj feem xyuam rau qhov hnyav ntawm cov khoom siv tshuaj (atoms, molecules, unit cells). Txij li thaum atoms, molecules, thiab chav tsev cell yog tsis tshua muaj me me; qhov loj ntawm ib tug particle yog negligibly me me. Yog li, qhov loj ntawm 1mol (qhov hnyav ntawm 6.0210 23 cov khoom hauv grams) yog siv los ua chav nyob hauv kev tshuaj xyuas ntau. Cov tshuaj sib txawv muaj qhov sib txawv ntawm cov molar loj (C -12.01 g mol-1, Mg-24.3050 g mol-1) vim lawv muaj ntau txoj haujlwm hauv lub nucleus. Ib yam li ntawd, qhov no ua rau muaj ntau yam tshwj xeeb molar loj qhov tseem ceeb rau cov tshuaj sib txuas (NaCl–58.4426 g mol-1). Formula mass yog xam los ntawm cov qauv empirical ntawm ib qho compound. Nws yog cov lej ntawm cov atomic huab hwm coj qhov tseem ceeb ntawm tus kheej cov khoom hauv cov qauv empirical (H2O-18.00 g mol-1). Qhov sib txawv tseem ceeb ntawm cov mis loj thiab molar loj yog tias, cov mis loj ntawm cov molecule los yog cov khoom sib xyaw yog qhov sib npaug ntawm cov atomic qhov hnyav ntawm cov atoms nyob rau hauv nws cov qauv empirical thaum molar loj yog qhov hnyav hauv grams ntawm 1 mol ntawm cov khoom.
Formula Mass yog dab tsi?
Cov mis loj ntawm ib lub molecule lossis ib qho sib xyaw yog qhov sib npaug ntawm qhov hnyav ntawm cov atoms hauv cov qauv empirical. Cov units ntawm formula mass "atomic mass unit" (amu).
Formula Mass Calculation
Example 1:
NaCl ntau npaum li cas (Atomic mass of Na=22.9898 amu, Atomic mass of Cl=35.4527 amu)?
Formula mass of NaCl=Na + Cl
=22.9898 amu + 35.4527 amu
=58.4425 amu
Example 2:
C2H5OH (C=12.011 amu, H=1.00794 amu, O – 15.9994 amu)?
Formula mass of C2H5OH=2C + 6H + O
=2(12.011 amu) + 6 (1.00794 amu) + (15.9994 amu)
=46 amu
Molar Mass yog dab tsi?
Molar mass txhais tau tias yog qhov loj ntawm 1mol ntawm cov khoom. Nws muaj units ntawm g / mol lossis kg / mol. Txhua yam tshuaj lom neeg lossis tshuaj lom neeg muaj tus nqi tshwj xeeb rau molar mass.
Molar mass=Mass of one particle(NA – Avogadro qhov tas li)
NA= 6.0221023mol-1
Molar Mass of Elements
Cov ntsiab lus sib txawv muaj qhov tshwj xeeb molar loj tus nqi vim tias lawv muaj cov lej sib txawv ntawm electrons, protons, thiab neutrons. Piv txwv li, Molar huab hwm coj Carbon yog 12.01 g mol-1.
Molar pawg ntawm Magnesium yog 24.3050 g mol-1.
Molar Mass of Molecules and Compounds
Cov molar ntawm cov dej (H2O) yog 18.00 g mol-1
Cov molar mass of Mg(OH)2 is 58.3197 g mol-1
| 1 mol ntawm | Number of particles | Molar mass |
| C (element) | 6.02210 23 atoms | 12.011 g mol-1 |
| Cu (element) | 6.0221023 atoms | 63.546 g mol-1 |
| Fe2O3 (ionic compound) | 6.02210 23 unit cells | 159.70 g mol-1 |
| Al(OH)3 (ionic compound) | 6.0221023 unit cells | 78.00 g mol-1 |
| CF4 (covalent compound) | 6.0221023 molecules | 88.01 g mol-1 |
| N2O5 (covalent compound) | 6.0221023 molecules | 108.011 g mol-1 |
| SiO2 (covalent compound) | 6.0221023 molecules | 60.09 g mol-1 |
Qhov txawv ntawm Formula Mass thiab Molar Mass yog dab tsi?
Definition of Formula Mass thiab Molar Mass
Formula Mass: Cov mis loj (formula hnyav) ntawm ib lub molecule yog cov lej ntawm cov atomic hnyav ntawm cov atoms hauv nws cov qauv empirical.
Molar Mass: Molar mass yog qhov hnyav hauv grams ntawm 1 mol ntawm cov khoom (Cov naj npawb ntawm cov khoom hauv ib mole yog sib npaug rau 6.02210 23).
Siv
Formula mass: Formula mass yog xam rau cov tshuaj sib xyaw. Nws yog suav nrog cov qauv empirical.
Molar mass: Molar mass yog xam rau cov tshuaj lom neeg uas muaj ntau lub hauv paus xws li cov khoom siv tshuaj, ionic thiab covalent chemical compounds.
Basis of Calculation
Formula mass: Cov tshuaj sib txawv hauv cov tshuaj sib xyaw ua ke muab cov mis sib txawv.
Molar masses: Cov atomic sib txawv ua rau qhov sib txawv ntawm molar masses. Lub atomic mass ntawm ib lub caij (hauv atomic mass units - amu) yog sib npaug rau nws "molar mass"
Example: Xav NH4NO3
Formula mass (NH4NO3): N + H + O
=(14.01 amu2) + (1.008 amu4) + (16.00 amu3)
=80.05 amu
Molar mass (NH4NO3) : 80.05 g mol-1
