H₂O apa MH₂O= (2*1)+16=18g/mol
compozitia procentuala din masa moleculara
18g..................2gH.........................16gO
100g .................X...............................Y
X=100*2/18=11,11%H
Y=100*16/18=88,89%O
compozitia procentuala din raportul de masa
Raportul de masa mH÷mO= 2÷16=1÷8
1+8=9g
9g apa..................1gH..................8g O
100g apa................X....................Y
X=100*1/9=11,11%H
Y=100*8/9=88,89% O
Na₂O oxid de sodiu , M Na₂O= (2*23)+16= 62g /mol
62g.............................46g..................16gO
100g..............................X.......................Y
X= 100*46/62=74,19% Na,
Y=100*16/62= 25,81% O
Raport de masa mNa÷mO= 46÷16=23÷8
23+8=31g
31g Na₂O .......................23gNa......................8gO
100g.....................................X.............................Y
X= 100*23/31= 74,19%Na
Y=100*8/31= 25,81 %O
CH₄ metan, MCH₄= 12+(1*4)=16g/mol
16gCH₄.........................12g C......................4g H
100g .............................X.................................Y
X= 100*12/16=75%C
Y=100*4/16=25% H
Raportul de masa mC÷mH= 12÷4=3÷1
3+1=4gCH₄ metan
4gCH₄......................3gC........................1gH
100g............................X..........................Y
X=100*3/4=75%C
Y=100*1/4=25%H
HCl acid clorhidric, MHCl=1+35,45=36,45g/mol
36,45gHCl....................1gH........................35,45Cl
100g...............................X..............................Y
X= 100*1/36,45=2,74%H
Y=100*35,45/36,45= 97,26% Cl
Raport de masa
mH÷mCl= 1÷35,45
1+35,45= 36,45g
36,45g HCl......................1g H.................35,45gCl
100g......................................X......................Y
X=2,74%H, Y= 97,26%Cl
NH₃, amoniac
Masa moleculara M NH₃ = 14+(1*3)=17g/mol
17gNH₃ ...........................14g N....................3gH
100g ................................X...............................Y
X= 100*14/17=82,35% N
Y=100*3/17= 17,65% H
Raportul de masa
mN÷ mH=14÷3
14+3=17g
17gNH₃....................................14gN........................3g H
100g...............................................X...................................Y
X= 82,35%N
Y=17,65%H
