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QAIPM-2011-Ch-1874: NEET 2011 Chemistry - Class 12 AIPM-2011-Ch-1874 Solution: A buffer solution is prepared in which the concentration of…
A buffer solution is prepared in which the concentration of is 0.30 M and the concentration of is 0.20 M. If the equilibrium constant for equals what is the pH of this solution? (log 2.7 = 0.43) 9.08 9.43 11.72 8.73
Multiple Choice Options
- A Mn > Fe > Cr > Co
- B Fe > Mn > Co > Cr
- C Co > Mn > Fe > Cr
- D Cr > Mn > Co > Fe
Step-by-Step Verified Solution
The order can be explained using the idea
of spin correlation. Spin correlation refers to lowering
of energy for like (parallel) spins. Spin correlation
leading to decrease in repulsion for electrons of like
spins than for electrons of different spins is called
exchange energy.
Spin correlation and its exchange energy gives an
electronic configuration a special stability which is
greatest for half-filled electronic configurations.
Mn 2+ (d 5
) gets stabilisation due to half-filled
configuration.
In Fe 2+ (d 6 ) the placing of one extra electron in a
subshell destabilises. Placing of 2 electrons in Co 2+
(d 7 ) destabilises it more. Cr 2+ (d 4 ) has one vacant
subshell. Fe 2+ gets more stabilisation compared to
Cr 2+ through exchange energy. So the order is as
follows:
Mn > Fe > Cr > Co