CHAPTER
1 Some Basic Concepts of Chemistry
Some Useful Conversion Factors 1g
1u = 1amu = (1/12)th of mass of 1 atom of C12 =
1Å = 10–10 m, 1nm = 10–9 m, 1 pm = 10–12 m NA
1 litre = 10–3 m3 =1 dm3 = 1.66 ×10–24 g
1 atm = 760 mm Hg or torr = 101325 Pa or Nm–2 For Elements
1 bar = 105 Nm–2 = 105 Pa 1 g atom = 1 mole of atoms = NA atoms
1 calorie = 4.184 J g atomic mass (GAM) = mass of NA atoms in g
1 electron volt (eV) = 1.6022 ×10–19 J
Mass ( g )
(1 J = 107 ergs) Mole of atoms =
GAM or Molar mass
Atomic Mass or Molecular Mass
Mass of one atom or molecule in a.m.u. For Molecule
C → 12 amu 1g molecule = 1 mole of molecule = NA molecule
NH3→ 17 amu g molecular mass (GMM) = mass of NA molecule in g.
Actual Mass Mass ( g )
Mole of molecule =
Mass of one atom or molecule in grams: GMM or Molar mass
C → 12 ×1.66 × 10–24 g
CH4 → 16 ×1.66 × 10–24 g 1 Mole of Substance
Contains 6.022 × 1023 particles.
Relative Atomic Mass or Relative Molecular Mass
Mass of one atom or molecule w.r.t. 1/12th of one 12C atom: Weighs as much as molecular mass/ atomic mass/ionic mass
C → 12 in grams.
CH4 → 16 If it is a gas, one mole occupies a volume of 22.4 L at 1 atm
It is unitless. & at 273 K or 22.7 L at STP.
Gram Atomic Mass or For Ionic Compounds
Gram Molecular Mass 1 g formula unit = 1 mole of formula unit = NA formula unit.
Mass of one mole of atom or molecule (in g):
g formula mass (GFM) = mass of NA formula unit in g.
C → 12 g
CO2 → 44 g Mass ( g )
Mole of formula unit =
GMM or Molar mass
It is also called as molar mass.
Vapour density
Definition of Mole
Ratio of density of vapour to the density of dihydrogen gas at
One mole is a collection of that many entities as there are number
similar pressure and temperature.
of atoms exactly in 12 gm of C-12 isotope.
The number of atoms present in exactly 12 gm of C-12 isotope Vapour density =
Molar mass
is called Avogadro’s number [NA = 6.022 × 1023] 2
1 Some Basic Concepts of Chemistry
Some Useful Conversion Factors 1g
1u = 1amu = (1/12)th of mass of 1 atom of C12 =
1Å = 10–10 m, 1nm = 10–9 m, 1 pm = 10–12 m NA
1 litre = 10–3 m3 =1 dm3 = 1.66 ×10–24 g
1 atm = 760 mm Hg or torr = 101325 Pa or Nm–2 For Elements
1 bar = 105 Nm–2 = 105 Pa 1 g atom = 1 mole of atoms = NA atoms
1 calorie = 4.184 J g atomic mass (GAM) = mass of NA atoms in g
1 electron volt (eV) = 1.6022 ×10–19 J
Mass ( g )
(1 J = 107 ergs) Mole of atoms =
GAM or Molar mass
Atomic Mass or Molecular Mass
Mass of one atom or molecule in a.m.u. For Molecule
C → 12 amu 1g molecule = 1 mole of molecule = NA molecule
NH3→ 17 amu g molecular mass (GMM) = mass of NA molecule in g.
Actual Mass Mass ( g )
Mole of molecule =
Mass of one atom or molecule in grams: GMM or Molar mass
C → 12 ×1.66 × 10–24 g
CH4 → 16 ×1.66 × 10–24 g 1 Mole of Substance
Contains 6.022 × 1023 particles.
Relative Atomic Mass or Relative Molecular Mass
Mass of one atom or molecule w.r.t. 1/12th of one 12C atom: Weighs as much as molecular mass/ atomic mass/ionic mass
C → 12 in grams.
CH4 → 16 If it is a gas, one mole occupies a volume of 22.4 L at 1 atm
It is unitless. & at 273 K or 22.7 L at STP.
Gram Atomic Mass or For Ionic Compounds
Gram Molecular Mass 1 g formula unit = 1 mole of formula unit = NA formula unit.
Mass of one mole of atom or molecule (in g):
g formula mass (GFM) = mass of NA formula unit in g.
C → 12 g
CO2 → 44 g Mass ( g )
Mole of formula unit =
GMM or Molar mass
It is also called as molar mass.
Vapour density
Definition of Mole
Ratio of density of vapour to the density of dihydrogen gas at
One mole is a collection of that many entities as there are number
similar pressure and temperature.
of atoms exactly in 12 gm of C-12 isotope.
The number of atoms present in exactly 12 gm of C-12 isotope Vapour density =
Molar mass
is called Avogadro’s number [NA = 6.022 × 1023] 2
