Balance o by using h2o why oxidation fe2 fe3 1e

This preview shows page 9 - 17 out of 53 pages.

3.Balance O by using H2O – why?
9.2.2 Deduce redox equations using half equations.
104.Balance H by using H+ - why?oxidation:  Fe2+  Fe3+ + 1e-reduction: MnO4- +5e- + 8H+ Mn2+ +4H2O6.Balance charges between the half reactions – ie.  make sure #e- will cancel out.oxidation:  5(Fe2+  Fe3+ + 1e-)reduction: MnO4- +5e- + 8H+  Mn2+ +4H2O9.2.2 Deduce redox equations using half equations.
116.Combine half-rxns5Fe2+  5Fe3+ + 5e-MnO4- +5e- + 8H+ Mn2+ + 4H2O5Fe2+ + MnO4- + 8H+  Mn2+ + 4H2O + 5Fe3+ 8.Check atom and charge balanceNotice there are usually only ions in these reactions.Where are they coming from and why don’t we see the other ions?9.2.2 Deduce redox equations using half equations.
12CH3OH (aq) + Cr2O72-(aq) → CH2O(aq) + Cr3+(aq)Answer:3CH3OH + 8H+ + Cr2O72- → 3CH2O + 2Cr3+ + 7H2O9.2.2 Deduce redox equations using half equations.
13Oxidized species(atom, ion, molecule, or compound)whichever species is oxidized (↑ oxidation #)Reduced specieswhichever species is reduced (↓ oxidation #)Oxidizing agentWhichever species CAUSES oxidation to occur—in other words, the oxidizing agent IS the reduced speciesReducing agentWhichever species CAUSES reduction to occur—in other words, the reducing agent IS the oxidized species9.2.3 Define the terms oxidizing agent and reducing agent.
MnO4- + Fe2+ → Mn2+ + Fe3+Oxidized speciesReduced speciesReducing AgentOxidizing Agent149.2.4 Identify the oxidizing and reducing agents in redox  equations.
15The feasibility of a redox rxn can be deduced from a reactivity series (similar to the activity series you used for single replacement rxn in sophomore chem.)Usually a certain species will give a particular product as a result of gaining/losing e-, this pair is referred to as a redox couple.ie. Na+ + e-  NaIf one species in a couple is a powerful oxidizing agent, the other half of the couple will be a weaker reducing agent.9.3.1 Deduce a reactivity series based on the chemical behavior of a group of oxidizing and reducing agents.
16Non-metals like to gain e-, thus they tend to be oxidizing agents (or oxidants)Metals like to loose e-, thus they tend to be reducing agents (or reductants)In the note taking guide you have the reactivity series from the IB Data Booklet…9.3.1 Deduce a reactivity series based on the chemical behavior of a group of oxidizing and reducing agents.

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture