Q1. Which shows more donor properties: NF3 or PF3? EXPLAIN. Ans PF3..can't find the reason anywhere..
Q2. Give reasons why cation vacancies in some crystals make them good catalysts.
Q3. Explain why:
(a) TiCl2 is a high melting solid while TiCl4 is a liquid.
(b) MnO4- has an intense purple colour.
(c) Transition metals are not good reducing agents , even though they have high standard reducing potentials. PS: is there any difference between "reducing" potential and "reduction" potential?
(d) The colour of [Co(H2O)6]+2 changes from pink to blue when it is dehydrated.
29Ans 1 ..... In case of PF3 there is pπ-dπ backbonding so that may be the reason..
Ans 3 (b) MnO4- purple colour is due to charge transfer from oxygen to manganese...
29Ans---3a That may be because TiCl2 is ionic..so may it is forming an ionic lattice so it has high melting point...while TiCl4 is covalent so it cannot form an ionic lattice and exists in liquid form due to weak van-der-wall interaction between the molecules...
well this may be the answer ..not sure abt it...someone plz confirm
1@govind: dont u think donor properties should decrease bcz of back bonding? neway, that MnO4 one seems correct. not sure abt the TiCl2 one...
13Nah, i think govind is rite. 'Coz of Back bonding, the + charge on the "P" atom after donation wud be stabilised more.
29Ans 3 d ...Actually the question shud be like this The colour of [Co(H2O)6]+2 changes from pink to blue when it is partially dehydrated...
on partial dehydration [Co(H2O)6]+2 chenges to [Co(H2O)4]+2 ..
pink blue
Now the reason for the colour change comes from CFSE...
[Co(H2O)6]+2 octahedral..
U may have read that when the number of lingands increases crystal field splitting energy increases.. so it will absorb high energy light(violet) to excite the electron and the complementary colour is emited(i.e pink or red)..
and in case of tetrahedral complex crystal field splitting energy is less compared to the abv case..so electron will require less energy(red) light to excite and hence the complementary colour is blue
11st one : PF3 is a better Lewis acid...that's the explanation.
As we go down the group as the electronegativity of P>N so PF3 is better donor.
1u mean electronegativity of P<N??? well...ya that cud be the reason....
but then why is ammonia more basic than phosphine???
1yes....NH3 surely is a stronger lewis base. that's what i'm asking: how cum NH3 is stronger base than PH3 whereas NF3 is a weaker one than PF3?? well now i think electronegativity shud not be the reason.
@govind: can u please explain it with back bonding in a little more detail?
