Given the equation representing a reaction:4Al(s) + 3O2 (g) → 2Al2O3(s) What is the change in oxidation state for aluminum in this reaction?
- Mayya Alocci
- Sep 17
- 1 min read
Regents Chemistry Exam June 2025 Question 40
43 Given the equation representing a reaction:
4Al(s) + 3O2 (g) → 2Al2O3(s)
What is the change in oxidation state for aluminum in this reaction?
(1) 0 to +3
(2) 0 to +6
(3) +3 to 0
(4) +6 to 0
Solution:
We can see that aluminum is on its own on the left side of the equation, which means its oxidation number must be zero. On the right side of the equation, aluminum is a part of the compound (Al2O3). When writing ionic formulas, we cross multiply the oxidation numbers. Since oxygen has 3 next to it, this number came from aluminum. Alumium must have been +3. Choice 1 is the correct answer.
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