Give the oxidation number of the element indicated for each compound.

a) carbon in Na2C2O4
b) nitrogen in HNO3
c) sulfur in H2SO4
d) carbon in HCO3 −
e) manganese in KMnO4
f) chromium in Cr2O7 2−

a. C: +3 ; b. N: +5 ; c. S:+6 ; d. C: +4; e. Mn: +7 ; f. Cr: +6.

Explanation:

Global charges in molecules is 0

You sum all the oxidation states to determine the oxidation state for the compound.

Na₂C₂O₄ → Sodium oxalate → Global charge: 0

Oxidation state for C: +3

HNO₃ → Nitric acid → Global charge: 0

Oxidation state for N: +5

H₂SO₄ → Sulfuric acid → Global charge: 0

Oxidation state for S: +6

HCO₃⁻  →  Bicarbonate → Global charge: -1, this is an anion

Oxidation state for C: +4

KMnO₄ → Potassium permanganate → Global charge: 0

Oxidation state for Mn: +7

Cr₂O₇⁻ → Anion dichromate → Global charge: -2

Oxidation state for Cr: +6

2b2t

explanation:

2b2t