Question

Predict which will be more stable, [CrO₄]²⁻ or [WO₄]²⁻, and explain.

a. [CrO₄]²⁻ is more stable due to higher electronegativity of chromium.
b. [WO₄]²⁻ is more stable due to higher electronegativity of tungsten.
c. [CrO₄]²⁻ is more stable due to smaller atomic size of chromium.
d. [WO₄]²⁻ is more stable due to smaller atomic size of tungsten.

Answer 1

[WO₄]²⁻ is more stable than [CrO₄]²⁻ because tungsten, being in the second and third transition series and lower in the periodic table than chromium, can more easily adopt higher oxidation states. The correct option is D.

Step-by-step explanation:

When comparing the stability of [CrO₄]²⁻ versus [WO₄]²⁻, we must consider the stability of higher oxidation states for transition metals. The stability of higher oxidation states generally increases down a group.

Since tungsten (W) is located below chromium (Cr) in the periodic table and belongs to the second and third transition series, it is more stable in higher oxidation states compared to chromium, which is in the first series and is more stable in lower oxidation states such as +3 rather than +4 or +5.

Therefore, the answer is that [WO₄]²⁻ is more stable than [CrO₄]²⁻, mainly due to the heavier tungsten having a higher ability to accommodate higher oxidation states like +6 commonly found in aqueous solution.