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3.1.7

Redox Flashcards

Interactive active recall cards for oxidation states, redox processes, and balancing half-equations.

Oxidation States & Rules: read all 6 questions and answers
  1. State the general rule for the oxidation state of elements in their standard state.
    The oxidation state of an uncombined element in its standard state is always 0.
  2. State the oxidation state of hydrogen in its compounds, and name the exception.
    Hydrogen is +1 in compounds, except in metal hydrides (e.g. NaH) where it is -1.
  3. State the oxidation state of oxygen in its compounds, and name the exceptions.
    Oxygen is -2 in compounds, except in peroxides (e.g. H2O2) where it is -1, and in OF2 where it is +2.
  4. What is the sum of oxidation states in a neutral compound?
    The sum of the oxidation states of all the atoms in a neutral compound is 0.
  5. What is the sum of oxidation states in a polyatomic ion?
    The sum of the oxidation states of all the atoms in a polyatomic ion is equal to the overall charge of the ion.
  6. What is the oxidation state of fluorine in all of its compounds?
    Fluorine is always -1 in all of its compounds because it is the most electronegative element.
Oxidation, Reduction & Agents: read all 6 questions and answers
  1. Define oxidation in terms of electron transfer.
    Oxidation is the loss of electrons, resulting in an increase in oxidation state.
  2. Define reduction in terms of electron transfer.
    Reduction is the gain of electrons, resulting in a decrease in oxidation state.
  3. What is an oxidising agent?
    An oxidising agent is an electron acceptor that oxidises other species and is itself reduced.
  4. What is a reducing agent?
    A reducing agent is an electron donor that reduces other species and is itself oxidised.
  5. What is a disproportionation reaction?
    A reaction in which an element in a single species is simultaneously oxidised and reduced.
  6. In the reaction: H2S + Cl2 → 2HCl + S, identify the reducing agent.
    H2S is the reducing agent because the sulfur in H2S is oxidised from -2 to 0 (loss of electrons).
Redox Half-Equations & Balancing: read all 6 questions and answers
  1. Define a redox reaction.
    A reaction in which both oxidation and reduction occur simultaneously.
  2. State the steps to balance oxygen and hydrogen in a half-equation in acidic conditions.
    1. Add H2O to balance oxygen atoms. 2. Add H+ ions to balance hydrogen atoms.
  3. How are electrical charges balanced in a half-equation?
    By adding electrons (e-) to the more positive side of the equation.
  4. How do you combine two half-equations to write a full redox equation?
    Multiply one or both half-equations so that the number of electrons lost equals the number gained, then add the equations and cancel the electrons.
  5. State the oxidation state of sulfur in the thiosulfate ion, S2O3^2-.
    The oxidation state of sulfur in S2O3^2- is +2.
  6. State the oxidation state of manganese in the manganate(VII) ion, MnO4^-.
    The oxidation state of manganese in MnO4^- is +7.
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