Question

what is the oxidation number for chromium in each of these compounds. show your work. A. K2CrO4 B.Cr2O3

Answer 1

Answer:

A. + 6.

B. + 3.

Explanation:

A. K₂CrO₄:

• To calculate the oxidation no. of an element in a compound:

We have that the sum of the oxidation no. of different elements in the compound multiplied by its no. is equal to the overall charge of the compound.

∵ 2(oxidation no. of K) + (oxidation no. of Cr) + 4(oxidation no. of O) = 0.

oxidation no. of K = + 1, oxidation no. of O = - 2.

∴ 2(+ 1) + (oxidation no. of Cr) +4(- 2) = 0.

∴ 2 + (oxidation no. of Cr) - 8 = 0.

∴ (oxidation no. of Cr) - 6 = 0.

∴ oxidation no. of Cr = + 6.

B. Cr₂O₃:

∵ 2(oxidation no. of Cr) + 3(oxidation no. of O) = 0.

oxidation no. of O = - 2.

∴ 2(oxidation no. of Cr) + 3(- 2) = 0.

∴ 2(oxidation no. of Cr) - 6 = 0.

∴ 2(oxidation no. of Cr) = + 6.

∴ (oxidation no. of Cr) = + 6/2 = + 3.