What is the oxidation number of copper in CuSO_4?

• A. +2
• B. 0
• C. +1
• D. +4

Answer: (A)

Verified step by step guidance

1. Identify the overall charge of the compound CuSO_4. Since it is a neutral compound, the sum of the oxidation numbers of all atoms must be zero.
2. Determine the oxidation number of the sulfate ion (SO_4). The sulfate ion has a charge of -2, and oxygen typically has an oxidation number of -2.
3. Calculate the total oxidation number contributed by the four oxygen atoms in SO_4: multiply the oxidation number of oxygen (-2) by 4.
4. Find the oxidation number of sulfur in SO_4 by using the fact that the sum of oxidation numbers in the sulfate ion equals its charge (-2). Set up the equation: oxidation number of sulfur + (oxidation number of oxygen × 4) = -2.
5. Use the overall neutrality of CuSO_4 to find the oxidation number of copper (Cu). Since the sulfate ion has a charge of -2, copper must have an oxidation number that balances this to zero. Set up the equation: oxidation number of copper + (oxidation number of sulfate ion) = 0, and solve for copper's oxidation number.