Estimation of closest distance of approach (derivation) of α-particle :
The radius of a nucleus : R = R0 (A)1/3 cm
Planck's Quantum Theory : Energy of one photon = hv = (hc/λ)
Bohr’s Model for Hydrogen like atoms :
De-Broglie wavelength :
Wavelength of emitted photon :
No. of photons emitted by a sample of H atom :
Heisenberg’s uncertainty principle:
Absolute density (mass/volume) =
Mgas = 2 V.D.
Mole fraction (x):
∴ Mole fraction of solution (x1) = ∴ Mole fraction of solvent (x2) =
Derive the following conversion :
M1 and M2 are molar masses of solvent and solute, ρ is density of solution (gm/mL)
M = Molarity (mole/lit.), m = Molality (mole/kg), x1 = Mole fraction of solvent, x2 = Mole fraction of solute
Average/Mean atomic mass :
Mean molar mass or molecular mass:
Calculation of individual oxidation number :
Formula: Oxidation Number = number of electrons in the valence shell - number of electrons left after bonding
Concept of Equivalent weight/Mass :
For elements, equivalent weight (E) =
Equivalent weight (E) = (v.f. = valency factor)
Concept of number of equivalents :
No. of equivalents of solute =
No. of equivalents of solute = No. of moles of solute x v.f.
Normality = Molarity x v.f.
Calculation of valency Factor :
n-factor of acid = basicity = no. of H+ ion(s) furnished per molecule of the acid,
n-factor of base = acidity = no. of OH- ion(s) furnised by the base per molecule.
At equivalence point:
Volume strength of H2O2:
20V H2O2 means one litre of this sample of H2O2 on decomposition gives 20 It. of O2 gas at S.T.P.
Measurement of Hardness:
Calculation of available chlorine from a sample of bleaching powder :
where x = molarity of hypo solution and v = mL. of hypo solution used in titration.