Why is freshly prepared saturated solution of ferrous sulphate is used in las?
Answers
Answered by
0
Ring test used to confirm NO3-(nitrate) radical is done using first by Freshly prepared FeSO4. There are many factors affecting the test,
first going the main concept, Reduction potential of No3- is more than Fe2+, or in other words we can say Fe2+ reduces NO3- to NO(Nitrosyl) while itself getting oxidised to Fe3+.
Fe2+ + NO3- —————— Fe3+ +NO
So, now Fe2+ always has a tendency to form Fe3+ as Fe3+ has d5 configuration(hence more stable than Fe2+ [having d6]). (Reason being half filled orbitals being more stable than partial filled).
Hence the need to prepare fresh FeSO4 (Fe2+) which can get oxidised to Fe3+ and hence reduce NO3- to NO.
[Note: An old prepared FeSO4 sol wil have Fe3+ which wont give the same reaction and wont be able to reduce NO3-].
After this step we add H2SO4 and a complex [Fe(H20)5NO]2+ is formed {which results due to charge transfer of Fe2+ to Fe+ and NO to NO+(Nitrosonium)}.
The complex having coloured appearance forms a ring at junction of two layer of liquids and hence is NO3- confirmed.
first going the main concept, Reduction potential of No3- is more than Fe2+, or in other words we can say Fe2+ reduces NO3- to NO(Nitrosyl) while itself getting oxidised to Fe3+.
Fe2+ + NO3- —————— Fe3+ +NO
So, now Fe2+ always has a tendency to form Fe3+ as Fe3+ has d5 configuration(hence more stable than Fe2+ [having d6]). (Reason being half filled orbitals being more stable than partial filled).
Hence the need to prepare fresh FeSO4 (Fe2+) which can get oxidised to Fe3+ and hence reduce NO3- to NO.
[Note: An old prepared FeSO4 sol wil have Fe3+ which wont give the same reaction and wont be able to reduce NO3-].
After this step we add H2SO4 and a complex [Fe(H20)5NO]2+ is formed {which results due to charge transfer of Fe2+ to Fe+ and NO to NO+(Nitrosonium)}.
The complex having coloured appearance forms a ring at junction of two layer of liquids and hence is NO3- confirmed.
Similar questions