[Ankesh]

We have read that Boron gives B203 AND BN in air.
But I think Boron should also give B2H6 in air.

See this,
        :delta:
B2H6 2B + 3H2
This is an endothermic reacn.
So, its reverse(:2B + 3H2 B2H6) should be exothermic and thus spontaneous at normal conditions.
So, Boron should also give B2H6 in air on reacn with H2
Please correct me if i am wrong.

[Borek]

In general there is no hydrogen in air. Some traces only.

[Ankesh]

C02 is also present in traces only.
But we consider it.

[orgoclear]

the percentage of H2 in the atmosphere is negligible even in comparision to the percentage of CO2.

Further, an exothermic reaction may not be spontaneous (as the reaction,here, has a negative entropy change which might make the free energy positive).

Thermodynamics MAY predict reaction as spontaneous (if you have free energy data) still then a reaction may not be feasible in reality because of the RATE of reaction (i.e. its kinetics)

Remember kinetics decides the rate of reaction while thermodynamics can only predict the extent of reaction

[Ankesh]

But at normal conditions,it would be spontaneous.
It would be non spontaneous only at a very high temp.
Further in these reacns  :delta: H >>>  :delta:  :delta: S.

[Ankesh]

the percentage of H2 in the atmosphere is negligible even in comparision to the percentage of CO2.

Okay ,tell me if we consider water vapour for reactions with air.
Water vapour is present is substantial amount all over the atmosphere(1%-3%)

[Borek]

Okay ,tell me if we consider water vapour for reactions with air.

Sure we do.