Ionic Compouds Flashcards
Are H20b, HF , CH3COOH polar ?
Yes , because there is a great electronegativity difference between the constituent ions
Polarity of a solvent Is directly proportional to ?
Dielectric constant
Water - 81
H2O > D20
Polarity of a solvent is the ability of decreasing attraction between opposite ions
What is the necessary condition for dissociation of an ionic solid
Hydration energy can be greater or lesser than lattice energy but they can’t be equal
LE > HE ( endothermic)
HE > LE ( exothermic)
Dissolution of salt in water is exo or endo
Endothermic LE > HE
What is used to determine the lattice energy of a crystal?
Born haber cycle
No direct method to determine lattice energy
What is solvation enthalpy ?
Complete hydration enthalpy
Enthalpy change surinf salvation of one mole of ionic solid into solvent
Delta Hr negative , exothermic
,,,,,,,,,,,,, positive , endothermic
Solubility is inversely proportional to lattice energy u knot , what all factors does LE depend on ?
Force of attraction is directly proportional to lattice energy is directly proportional to Kq1q2 / r2
But because LE is energy
It is directly proportional to q1q1/r
LE directly proportional to q1q2
And inversely proportional to interionic distance (r- + r+)
Always remember, in questions where you have to choose between charge and size factor, charge will be a dominating factor …
Arrange in decreasing order of solubility
LiF , LiCl , LiBr , LiI
Give are reason why you arranged them so …
LiF < LiCl < LiBr < LiI
The size of cation is very small in comparison to anions , so lattice energy is inversely proportional to size of anions , and therfore solubility is directly proportional to size of anions
Factors affecting hydration energy? (Individual)
Directly proportional to charge and 1/r- + 1/r+
Is size of aqueous ions directly proportional to hydration ?
I guess !!
Kidding yes it is
Arrange in increasing order of solubility
LiF NaF KF RbF CsF
LIF < NaF <KF<RbF<CsF
Size of cations and anions almost similar , and increasing , so le and he both decrease but decrease in le is more so solubility increases only
Which of the following are large anions ?
H- , F - Cl - , o2- , NO3 - , CO32- SO42- S2O32- ClO4- CrO4- , OH-
NO3- , CO32- AO42- S2032-( thiosulfate ion ) ClO4- (PERCHLORATE ION) , CrO42-
All others are small ions
Cations of 2nd and 3rd period are taken as small cations
H- is greater in size or F- ?
H- is because in it for one proton two electrons are there , so very big difference in ENC would be there
Arrange in order of increasing solubility
NaOH , Mg(OH)2 , Al(OH)3
Al(OH)3 < Mg(OH)2 < NaOH
This is because in comparison to Al3+ , Mg2 + , Na+ is bigger in size so NaOH because SL combination
Arrange the chloride of group 1 in order of decreasing covalent character
LiCl>NaCl>KCl>RbCl>CsCl
Li is smallest cation so LiCl has max . Polarization , therfore it is most covalent, and has minimum melting point, dissolves in organic solvents like ether , Pyrene , pyridine, benzene
What is the colour of the following compounds-
Silver chloride
PbCl2
Sn Cl2
HgCl2
AgI
PbI2
SnI2
HgI2
AG
gF
AgCl
AgBr
LiI
AgCl, Pbcl2 , sncl2 , hgcl 2 , agf , LiI are colorless or have white colour and AgI , pbi2 , sni2 have bright yellow colour and hgi2 has bright red colour
All s block iodides are colorless their cations are the largest in their groups and can’t cause polarization in visible region
