d-orbital

What causes the variability in oxidation states of d-block elements?

The involvement of (n-1)d and ns electrons in bonding.

What is the oxidation state and color of Chromium(III)?

Oxidation state +3, color is violet/green.

What are the oxidation states of Manganese and their associated color in MnO4−?

Oxidation states +2, +4, +7; associated color in MnO4− is purple.

What color does Iron(II) exhibit?

Pale green.

What is the coordination number change associated with ligand exchange?

Ligand exchange can alter the coordination number depending on the ligands involved.

What is the coordination number of the complex [Cu(H2O)6]^{2+}?

The coordination number is 6.

What is the color and formula of the cobalt(II) complex in aqueous solution?

Color is pink, formula is [Co(H2O)6]^{2+}.

What type of bond exists between metal ions and ligands in tetrahedral and octahedral complexes?

Coordinate bonds.

What is responsible for the color in transition metal complexes?

Color arises from d-d transitions influenced by crystal field splitting.

Which catalyst is used in the hydrogenation of alkenes?

Nickel (Ni).

Name an example of a catalyst used in the contact process.

V2O5.

What is the precipitate formed with excess aqueous OH- for Cu^{2+}?

Blue precipitate of Cu(OH)2.

What indicates the presence of Cr^{3+} in a reaction with excess aqueous OH-?

A green precipitate of Cr(OH)3 is formed.

What color is expected when Fe^{3+} reacts with aqueous OH-?

A brown precipitate of Fe(OH)3.

What is the expected precipitate and color for Fe^{2+} when reacted with excess aqueous OH-?

A green precipitate of Fe(OH)2.

What color does the coordination complex [Cu(NH3)4(H2O)2]^{2+} exhibit?

Deep blue.

What is the color of the tetrahedral complex [CuCl4]^{2−}?

Yellow/green.

How do heterogeneous and homogeneous catalysis differ in transition metals?

Heterogeneous catalysis involves surface adsorption, while homogeneous catalysis involves variable oxidation states.