What is the oxidation number of aluminum in Al2O3?

• A. +2
• B. -3
• C. +3
• D. 0

Answer: (C)

Verified step by step guidance

1. Recall that the oxidation number of oxygen in most compounds is typically -2.
2. Write the formula for aluminum oxide: \(\mathrm{Al_2O_3}\), and assign the oxidation number of oxygen as -2.
3. Set up an equation where the sum of the oxidation numbers of all atoms in the compound equals zero (since the compound is neutral): \$2 \times \mathrm{(oxidation\ number\ of\ Al)} + 3 \times (-2) = 0$.
4. Solve the equation for the oxidation number of aluminum: \$2x - 6 = 0\(, where \)x$ is the oxidation number of aluminum.
5. Calculate \(x\) to find the oxidation number of aluminum, which will be \(+3\).