Chemical Composition and Oxidation State Calculation in Na₃PW₁₂O₄₀

What is the average oxidation state of tungsten in sodium phosphotungstate, Na₃PW₁₂O₄₀?

(A) +6.00 (B) +6.17 (C) +6.42 (D) +6.67

Answer:

The average oxidation state of tungsten, W in Na₃PW₁₂O₄₀ is +6.67. The correct answer is Option D.

The oxidation number of individual elements in Na₃PW₁₂O₄₀ is as follows: Sodium (Na) = +1 Phosphorus (P) = -3 Oxygen (O) = -2 Tungsten (W) = unknown

The oxidation number of tungsten, W in Na₃PW₁₂O₄₀ can be calculated as follows: Na₃PW₁₂O₄₀ = 0 (group state) 3Na + P + 12W + 40O = 0 3(1) + (-3) + 12W + 40(-2) = 0 3 - 3 + 12W - 80 = 0 12W - 80 = 0 12W = 80 W = 80 / 12 W = +6.67

Therefore, the oxidation number of tungsten, W in Na₃PW₁₂O₄₀ is +6.67.