P-block XII (grp 15,16..) Flashcards
N2 is ______ while others are
N2 is diatomic others are polyatomic.
All except ____ show allotropy. (In grp 15)
N
N cant form d π - p π bond ??
Bcz of absence of d-orbital
But can show p π - p π bond
Common oxidation state of grp 15 is
+3,-3,+5
Tendency to show -3 oxidation state ______ down the grp due to??
Decreases.
Due to increase in size and metallic character.
____ hardly forms any cmpd in -3 oxi. State?
Bi
Stability of ____ oxi. State increases while of ____ decreases down the group.(grp 15)
+3 increases , +5 decreases
Due to inert pair effect.
Characteristic compound of Bi in +5 oxi. State is??
BiF5
3HNO2 —->
HNO3 +H2O +2NO
All elements of group 15 form hydrides of the form EH3.
T/F
T
Thermal stability, basicity,bond dissociation enthalpy, bond angle of hydrides of grp 15 _____ down the grp.
Decrease.
Reducing charac. Increases down the grp.
Boiling point order for hydrides of grp 15 is
PH3
Melting point order of grp 15 hydrides is
PH3
Boiling point order of grp 15
N <p></p>
Melting point order of grp 15 elements
N <p></p>
Chile saltpeter is
NaNO3
Indian saltpeter is
KNO3
+3 oxi. State of __,__,__ become stable with respect to disproportionation. (Grp 15)
As, Bi, Sb
Oxide in higher oxi. State are more stable than in lower oxi. State.
(T/F)
T
Designate acidic, amphoteric, basic to oxides of grp 15 of the form E2O3.
N2O3 and P2O3 = purely acidic
As2O3 and Sb2O3 = amphoteric
Bi2O3 = predominately basic
Give nature of N2O, NO, NO2
N2O & NO = neutral oxides
NO2 = mixed anhydride
All trihalides except of ___ are unstable. (Grp 15)
N
Only NF3 is known to be stable.
Except BiF3 other trihalides are predominantly covalent.
Except ___ all trihalides of grp 15 are predominantly covalent.
BiF3
Preparation of dinitrogen
In laboratory,
NH4Cl + NaNO3 —> N2 + 2H2O + NaCl
Thermal decomposition of sodium/barium azide (for very pure N2),
Ba(N3)2 ——> Ba + 3N2
2NaN3 —-> 2Na + 3N2
{N3^-1 is k/a azide.}
6Li + N2 —->
3Mg + N2 —->
2Li3N
Mg3N2
At high temperature,
N2 + O2 —-> 2NO
True
Preparation of ammonia
On small scale,
NH4Cl + Ca(OH)2 —->2NH3 + 2H2O + CaCl2
On large scale, by Haber’s process,
N2 + 3H2 ——>NH3 ΔH = -46.1 Kj/mol (exothermic)
Optimum conditions for formation of ammonia are?
High pressure
Temperature ≈ 700K
Cu^2+ (blue) + 4NH3 ——>
AgCl (white ppt.) + 2NH3 ——>
Cu^2+ (blue) + 4NH3 ——> [Cu(NH3)4]^2+ (deep blue)
AgCl (white ppt.) + 2NH3 ——> [Ag(NH3)2]Cl (colourless)
NH3 is highly soluble in water.
Precipitates hydroxides of many metals from their salts.
Forms ammonium salt with acids.
Is a lewis base.
Which one of these is true?
All are true.
Preparation of nitric acid?
In laboratory,
NaNO3 + H2SO4 ——> NaHSO4 + HNO3
On large scale by Ostwald’s process,
3 step process.
Ostwald’s process ??
1) 4NH3 + 5O2 ——> 4NO + 6H2O. (In presence of Pt/Rh gauge catalyst)
2) 2NO + O2 ——>2NO2
3) 3NO2 + H2O ——> HNO3 + NO
