Worksheet: Oxidation States

In this worksheet, we will practice determining the oxidation state of an element in a compound from the Lewis diagram or molecular formulas.

Q1:

Which of the following statements is true?

  • AAtoms or ions of the same element in a compound must have the same oxidation state.
  • BOnly atoms in an element can have an oxidation state of 0.
  • CThe oxidation state and formal charge of an atom in a compound must have the same sign.
  • DThe sum of oxidation states in a compound must equal the charge of the compound.
  • EThe oxidation state of an atom in a compound must always be a whole number.

Q2:

Which of the following statements is false?

  • AThe compounds NaVO34, KBrO3, and NO2+ all contain atoms or ions in the +5 oxidation state.
  • BThe compounds AlSe23, PCl3, and NaClO2 all contain atoms or ions in the +3 oxidation state.
  • CThe compounds BaCl2, NaSO223, and NO all contain atoms or ions in the +2 oxidation state.
  • DThe compounds MnO2, HSO23, and ZrCl4 all contain atoms or ions in the +4 oxidation state.
  • EThe compounds NaO22, NHOH2, and LiH all contain atoms in the 1 oxidation state.

Q3:

Calculate the oxidation state of iridium in the IrO4+ ion.

  • A+7
  • B+3
  • C+5
  • D+9
  • E+8

Q4:

Which of the following statements is true?

  • AThe valency of a group 13 atom in a neutral compound is typically an even number.
  • BThe oxidation state of oxygen can never be negative.
  • CGroup 1 elements usually form ions with a negative charge.
  • DThe oxidation state of a halogen in a salt is typically positive.
  • EThe oxidation state of a chalcogen in a salt is typically an even number.

Q5:

What is the oxidation state of Mn in KMnO4?

  • A+5
  • B+8
  • C+6
  • D+4
  • E+7

Q6:

What is the oxidation state of I in IO3?

  • A+1
  • B+3
  • C+5
  • D+6
  • E+7

Q7:

What is the oxidation state of Al in AlCl4?

  • A3
  • B+3
  • C1
  • D+2
  • E+4

Q8:

What is the oxidation state of Cl in HClO2?

  • A1
  • B+1
  • C+5
  • D+3
  • E3

Q9:

The oxidation state of O is affected by the presence of OO and OF bonds.

What is the oxidation state of O in FO2?

  • A2
  • B+2
  • C0
  • D1
  • E+1

What is the oxidation state of O in ClO3?

What is the oxidation state of O in HO22?

What is the oxidation state of O in NaO2?

Q10:

The oxidation state of N is affected by the presence of NN, NO, NF, and NCl bonds.

What is the oxidation state of N in NI3?

What is the oxidation state of N in NCl3?

  • A3
  • B+2
  • C+6
  • D+3
  • E2

What is the oxidation state of N in NO?

  • A3
  • B+1
  • C2
  • D+2
  • E+3

What is the oxidation state of N in NO2?

  • A0
  • B1
  • C+4
  • D+2
  • E+3

Q11:

What is the oxidation state of I in ICl?

  • A2
  • B+1
  • C0
  • D+2
  • E1

Q12:

What is the average oxidation state of N in nitrous oxide, NO2?

  • A1
  • B+1
  • C+3
  • D0
  • E3

Q13:

Consider the following: NNO+ What is the average oxidation state of N in nitrous oxide (NO)2?

Q14:

What is the oxidation state of P in PO33?

  • A+6
  • B+3
  • C+9
  • D+2
  • E+5

Q15:

What is the oxidation state of P in PO410?

  • A3
  • B+5
  • C5
  • D+3
  • E+2.5

Q16:

What is the average oxidation state of S in tetrathionate, SO462?

  • A+2.5
  • B1
  • C+1.5
  • D+1
  • E+3

Q17:

What is the oxidation state of C in hydrogen cyanide (HCN)?

HCN

Q18:

What is the average oxidation state of S in the thiosulfate ion (SO)232?

SOOOS

Q19:

What is the average oxidation state of S in the tetrathionate ion (SO)462?

SSOOOSSOOO

Q20:

What is the oxidation state of N in dinitrogen pentoxide (NO)25?

ON+OON+OO

Q21:

What is the average oxidation state of chlorine in chlorine perchlorate (ClO)24?

OClOOOCl

Q22:

In which of the following compounds does the transition metal display the highest oxidation state?

  • APotassium manganate(VII)
  • BCopper(I) fluoride
  • CManganese(IV) oxide
  • DIron(III) chloride
  • ESodium chromate(VI)

Q23:

Which of the following statements is true?

  • AHydrogen ions can never act as a reducing agent.
  • BAcid–base reactions always involve two different species.
  • CAcid–base reactions always produce water.
  • DMolecular oxygen can never act as a reducing agent.
  • EReduction–oxidation reactions always produce at least two different species.

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