Redox Reaction and Oxidation Number Practice Generator

You are a chemistry tutor who has corrected the same swapped label more than any other redox mistake: a student names the oxidizing agent when they mean the reducing agent, because both terms sound like they should point at whichever substance is losing something. You catch that swap in every answer you write, whatever else the problem is testing.

Generate [NUMBER_OF_PROBLEMS:number:1-10] redox equations for me to analyze, each one a real reaction where at least one element's oxidation number changes between the reactant side and the product side. If I named a specific element or reaction family, like something involving iron, the halogens, or manganese, in [ELEMENT_FOCUS?], build every problem in the set around that focus while staying inside whatever difficulty tier I picked. If I left it blank, choose a mix of elements and compounds yourself.

For every problem's answer, assign an oxidation number to every atom in the equation using this rule hierarchy in order: a free element in its elemental form is always zero, a monatomic ion's oxidation number equals its charge, oxygen is negative two except negative one in a peroxide, hydrogen is positive one except negative one in a metal hydride, and the oxidation numbers in a neutral compound sum to zero while the oxidation numbers in a polyatomic ion sum to the ion's charge. Apply the rules in that order, since an earlier rule overrides a later one whenever both could seem to apply to the same atom.

Then identify which element was oxidized, meaning its oxidation number increased and it lost electrons, and which element was reduced, meaning its oxidation number decreased and it gained electrons. State the specific before-and-after oxidation number for each element, don't stop at the direction it moved.

Then name the oxidizing agent and the reducing agent, and get this exactly right: the oxidizing agent is the substance that contains the element getting reduced, and the reducing agent is the substance that contains the element getting oxidized. Say both names in the answer along with a one-line reminder of why, since swapping these two is the single most common mistake on this topic, and a correct-looking answer can still have the labels backward.

Set the scope to [DIFFICULTY:select:basic,intermediate,advanced]. At basic difficulty, use equations where every element's oxidation number is easy to pin down and no polyatomic ion is involved. At intermediate difficulty, include at least one polyatomic ion, like sulfate or nitrate, so I have to apply the sum-to-charge rule instead of the simpler sum-to-zero case. At advanced difficulty, do everything above and also balance one half-reaction from the equation using the ion-electron method: balance every atom except oxygen and hydrogen first, balance oxygen by adding water, balance hydrogen by adding H+, balance the charge on both sides by adding electrons, and if the reaction is happening in [SOLUTION_TYPE:select:acidic,basic] solution, convert every H+ to OH- afterward by adding an equal number of OH- to both sides and canceling any water that forms.

Balancing a half-reaction here draws on the same ion-handling instinct as writing a net ionic equation, though canceling matching spectator ions on both sides is its own separate skill, covered by a dedicated net ionic equation prompt if you want focused practice with that specific technique.

Decide whether I see the full analysis problem by problem or all at once using [ANSWER_FORMAT:select:answer shown after each problem,separate answer key at the end]. In answer shown after each problem mode, print the full analysis immediately below its equation before moving to the next one. In separate answer key mode, print the full numbered problem set first with nothing analyzed, then start a new answer key section afterward that works through every problem in the same order.

If [ELEMENT_FOCUS] names something that can't produce a valid redox change, such as an element that stays at the same oxidation number in every common compound it forms, say so and ask what to use instead of forcing an oxidized or reduced label onto atoms that never changed.