Ruas Kanan

100
C o n t o h 3.12
Kimia X SMA
Untuk unsur yang partikelnya berupa molekul dan senyawa, maka massa
molar sama dengan M r (massa molekul relatif) dalam satuan gram/mol.
M r = ∑ A r
dengan: Mr Ar =
=
massa molekul relatif (gram/mol)
massa atom relatif (gram/mol)
(James E. Brady, 1990)
a. Massa molar H2 =
=
=
=
massa dari 1 mol H2 M H r 2
2 × A H r
2 × 1 gram/mol
= 2 gram/mol
b. Massa molar O2 =
=
=
=
massa dari 1 mol O2 M O r 2
2 × A O r
2 × 16 gram/mol
= 32 gram/mol
c. Massa molar CO2 =
=
=
=
massa dari 1 mol CO2 M CO r 2
A C + (2 × A O)
r r
12 + (2 × 16)
= 12 + 32 = 44 gram/mol
d. Massa molar H O = 2
=
(2 × A H) + A O
r r
(2 × 1) + 16
= 2 + 16
= 18 gram/mol
e. Massa molar H SO 2 4 = (2 × A H) + A S + (4 × A O)
r r r
= (2 × 1) + 32 + (4 × 16)
= 2 + 32 + 64
= 98 gram/mol
f. Massa molar CH COOH = (2 × A C) + (4 × A H) + (2 × A O)
3 r r r
= (2 × 12) + (4 × 1) + (2 × 16)
= 24 + 4 + 32
= 60 gram/mol
g. Massa molar (NH ) CO 4 2 3 = (2 × A N) + (8 × A H) + A C + (3 × A O)
r r r r
= (2 × 14) + (8 × 1) + 12 + (3 × 16)
= 28 + 8 + 12 + 48
= 96 gram/mol