Q1 Is HF dibasic acid ?
Q2 Arrange Cl2,Br2,F2,I2 in dec. oxidising power
Q3 Oxalic acid +conc.H2SO4 → ??
11Chlorine has the highest EA so gaseous Cl atoms accept electrons most readily.However,Cl is not the strongest oxidizing agent,,F2 is the strongest oxidizing agent.
The change in order is basically due to :
1. F2's weak bond..
2. F2 has high free energy of dissociation ( due to small F- )
There is a quite a big thermodynamic explanation to it..u will get it in J D LEE eure..
11Ans 2) Oxidising power is in the order :-
F2 > Cl 2 > Br 2 > I 2
The oxn potential is the enrgy change b/w the elements in the standard state, and its hydrated ions.
F2 has the most negative Free energy value, hence, it is the strongest oxodosing agent and can oxidise Cl - , Br - , and I - to respectively Cl2 , Br 2 and I2.
F2 can also oxodose H2O to O2.
F2 + H2O → 2 HF + (1/2) O2
Similarily Cl 2 will oxodose Br - and I - , and Br2 will oxidise I-.
In general any halogen (X 2) of lower atomic number will oxidise halide ions (X- ) of higher atomic number.
11HF is a weak dibasic acid ( due to strong H-F bond) and forms two series of salts
NaOH + H2F2 -------> NaHF2 + H2O
NaHF2 + NaOH ------> 2NaF + H2O.
39Oxidising power of an element depends on its electrode potential, which in turn depends on 3 factors -:
1) Bond dissociation enthalpy - Should be less
2) Hydration energy - Should be great
3) Electron gain enthalpy - Should be more negative
We find that chlorine has a more negative electron gain enthalpy than fluorine, but it is overruled because -:
1) Due to small size and high(est) electronegativity, the F-F bond has a very low bond dissociation enthalpy.
2) Fluorine's hydration energy is very high due to its small size.
This culminates in fluorine having a more positive electrode potential than chlorine, which means greater oxidising power.
Aaj hi p-block padha maine :P
1Q.3) i hv a different view.
if conc. H2SO4 is rected with oxalic acid , then conc. H2SO4 acts as an oxidising agent , oxidising oxalate to carbondioxide and self reducing to sulphur dioxide.
H2SO4 + H2C2O4 → CO2 + SO2 + H2O.
rest , i agree wid the answers given
1k. no prob. so, it acts as catalyst only , but strange , only oxidation of oxalic acid to CO2 is occuring.
1Hey aieee,in the reaction
H2SO4 + H2C2O4 → CO +CO2 +H2O,
H2SO4 acts as a dehydrating agent removing water from Oxalic acid and not oxidising agent,indeed it does not itself undergo any change!
