# 3.4.1: Formal Charge and Oxidation State (Problems)

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PROBLEM $$\PageIndex{1}$$

Determine the formal charge and oxidation state of each element in the following:

a. HCl
b. CF4
c. PCl3

FC: H: 0, Cl: 0

OX: H: +1, Cl: -1

FC: C: 0, F: 0

OX: C: +4, F: -1

FC: P: 0, Cl: 0

OX: P: +3, Cl: -1

PROBLEM $$\PageIndex{2}$$

Determine the formal charge and oxidation state of each element in the following:

a. H3O+
b. $$\ce{SO4^2-}$$

c. NH3
d. $$\ce{O2^2-}$$

e. H2O2

FC: H: 0, O: +1

OX: H: +1, O: -2

FC: S: +2, O: -1

OX: S: +6, O: -2

FC: N: 0, H: 0

OX: N: -3, H: +1

FC: -1

OX: -1

FC: O: 0, H: 0

OX: O: -1, H: +1

PROBLEM $$\PageIndex{3}$$

Calculate the formal charge and oxidation state of chlorine in the molecules Cl2 and CCl4.

FC: Cl in Cl2: 0; Cl in CCl4: 0

OX: Cl in Cl2: 0; Cl in CCl4: -1

PROBLEM $$\PageIndex{4}$$

Calculate the formal charge and oxidation state of each element in the following compounds and ions:

a. F2CO
b. NO
c. $$\ce{BF4-}$$

d. $$\ce{SnCl3-}$$
e. H2CCH2
f. $$\ce{PO4^3-}$$

FC: C: 0, F :0, O: 0

OX: C: +4, F: -1, O: -2

FC: N: -1, O: 0

OX: N: +1, O: -2

FC: B: -1, F: 0

OX: B: +3, F: -1

FC: Sn: -1; Cl: 0

OX: Sn: +2, Cl: -1

FC: C: 0, H: 0

OX: C: -2, H: +1

FC: P: +1, O: -1

OX: P: +5, O: -2

PROBLEM $$\PageIndex{5}$$

Based on formal charge considerations, which of the following would likely be the correct arrangement of atoms in nitrosyl chloride: ClNO or ClON?

ClNO

PROBLEM $$\PageIndex{6}$$

Based on formal charge considerations, which of the following would likely be the correct arrangement of atoms in hypochlorous acid: HOCl or OClH?

HOCl

PROBLEM $$\PageIndex{7}$$

Based on formal charge considerations, which of the following would likely be the correct arrangement of atoms in sulfur dioxide: OSO or SOO?

OSO

PROBLEM $$\PageIndex{8}$$

Draw the structure of hydroxylamine, H3NO, and assign formal charges; look up the structure. Is the actual structure consistent with the formal charges?

The structure that gives zero formal charges is consistent with the actual structure: PROBLEM $$\PageIndex{9}$$

Which of the following structures would we expect for nitrous acid? Determine the formal charges: 