What data (information) have you been given in the question?.(Based on the StoPGoPS approach to problem solving.)ĭetermine if the redox reaction as written is spontaneous. Is this redox reaction as written spontaneous or non-spontaneous? Play the game now! Worked Example: Given E o for the Redox ReactionĬa 2+ (aq) + Zn (s) → Ca (s) + Zn 2+ (aq) E o = -2.11 V You will need to refer to a table of Standard Reduction Potentials in order to determine the standard electrode potential for a given redox reaction.Ī table of Standard Reduction Potentials is given below: If E o for the redox reaction as written is negative, the reaction DOES NOT proceed in the forward direction and is said to be non-spontaneous.If E o for the redox reaction as written is positive, the reaction proceeds in the forward direction and is said to be spontaneous.How to decide if a redox reaction as written is spontaneous: The electrode potential for a redox reaction is the sum of the electrode potential for the reduction reaction and the electrode potential for the oxidation reaction:Į o (redox) = E o (reduction) + E o (oxidation).That is if E o for the reduction reaction is positive then it will be negative for the oxidation reaction. The electrode potential for an oxidation reaction will have the opposite sign to the one given in the table, The electrode potential for a reduction reaction can be read straight from the table. For each reaction there is an associated electrode potential measured in volts.Įlectrode potentials are usually tabulated for the reduction reaction in which the species are present in their standard states, and these tables are referred to as tables of "Standard Reduction Potentials".Ī table of standard reduction potentials is given below this discussion.(b) Oxidation reaction: a species loses electrons (a) Reduction reaction: a species gains electrons Redox reactions are made up of two reactions:.Revision (see Standard Electrode Potentials for Redox Reactions Tutorial for fuller discussion): No ads = no money for us = no free stuff for you! Using Electrode Potentials to Determine if a Redox Reaction is Spontaneous or Not Note: The reaction will be spontaneous in the reverse direction!Īnd non-spontaneous redox reactions cannot be used to produce electricity. If E o (redox reaction) is negative (E o (redox reaction) Spontaneous redox reactions can be used to produce electricity If E o (redox reaction) is positive, the reaction will proceed in the forward direction (spontaneous).That is, E o (redox reaction) is positive A redox reaction is spontaneous if the standard electrode potential for the redox reaction, E o (redox reaction), is positive.Į o (redox reaction) = E o (reduction reaction) + E o (oxidation reaction).You need to become an AUS-e-TUTE Member! Spontaneous Redox Reactions and Non-spontaneous Redox Reactions Chemistry Tutorial Key Concepts Want chemistry games, drills, tests and more? Spontaneous and Non-spontaneous Redox Reactions Chemistry Tutorial More Free Tutorials Become a Member Members Log‐in Contact Us
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