Top topic this week
Back to FAQs
Related FAQs
Frequently Asked Question
Questions asked by users might not always be phrased in the clearest way.
A student opens a container of hexaaquamanganese ii and realises that it is a pale yellow despite containing transition metal ion. What results in this colour
Accepted Answer
The pale yellow color of hexaaquamanganese(II) [Mn(H2O)6]2+ is due to a combination of factors:
1. d-Orbital Splitting: Manganese(II) has a d5 electronic configuration. In an octahedral complex like [Mn(H2O)6]2+, the d orbitals split into two energy levels, eg and t2g. The energy difference between these levels, called the crystal field splitting energy (Δo), determines the color of the complex.
2. Weak Ligand Field: Water is a weak ligand, resulting in a small Δo. This means that the energy difference between the eg and t2g orbitals is relatively low.
3. High Spin Complex: In a weak ligand field, the d electrons occupy the orbitals individually (high spin) before pairing up. This leads to a relatively high spin state for Mn(II) in [Mn(H2O)6]2+.
4. d-d Transitions: When a photon of light with energy equal to Δo is absorbed, an electron can be excited from a t2g orbital to an eg orbital. The color observed is the complementary color of the light absorbed. In the case of [Mn(H2O)6]2+, the weak ligand field results in a small Δo, which corresponds to the absorption of light in the blue-green region of the visible spectrum. This leaves the complementary color, pale yellow, to be transmitted and observed.
Articles you might like