redox

Examples of redox in the following topics:

• Redox Titrations

  • Redox titration determines the concentration of an analyte containing either an oxidizing or a reducing agent.
  • A student conducts the redox titration and reaches the endpoint after adding 25 mL of the titrant.
  • There are various other types of redox titrations that can be very useful.
  • A redox titration using potassium permanganate as the titrant.
  • Calculate the concentration of an unknown analyte by performing a redox titration.

• Types of Redox Reactions

  • Redox reactions are all around us.
  • In fact, much of our technology, from fire to laptop batteries, is largely based on redox reactions.
  • Redox (reduction-oxidation) reactions are those in which the oxidation states of the reactants change.
  • In some redox reactions, substances can be both oxidized and reduced.
  • This is an example of a combustion reaction, a redox process.

• Balancing Redox Equations

  • For example, look at the following redox reaction between iron and copper:
  • If a reaction occurs in an acidic environment, you can balance the redox equation as follows:
  • The following is an unbalanced redox equation that takes place in acidic solution:
  • A great walkthrough on how to balance a redox reaction in basic solution.
  • A great walkthrough on how to balance a redox reaction in acidic solution.

• Thermodynamics of Redox Reactions

  • The thermodynamics of redox reactions can be determined using their standard reduction potentials and the Nernst equation.
  • In order to calculate thermodynamic quantities like change in Gibbs free energy $\Delta G$ for a general redox reaction, an equation called the Nernst equation must be used.
  • Translate between the equilibrium constant/reaction quotient, the standard reduction potential, and the Gibbs free energy change for a given redox reaction

• Predicting Spontaneous Direction of a Redox Reaction

  • The direction of a redox reaction depends on the relative strengths of the oxidants and reductants in a solution.
  • Generally, the direction of a redox reaction depends on the relative strengths of oxidants and reductants in a solution.
  • In order to predict if two reactants will take part in a spontaneous redox reaction, it is important to know how they rank in an electrochemical series.
  • Predict the direction of electron flow in a redox reaction given the reduction potentials of the two half-reactions

• Balancing Redox Equations

  • Balancing redox reactions depends on conservation of mass and electrons; the exact method varies with basic or acidic solutions.
  • Redox (oxidation-reduction) reactions include all chemical reactions in which atoms have their oxidation states changed.
  • An alternative method for balancing reduction/oxidation (redox) reactions.
  • It consists of four steps that, if followed, can balance any redox equation.
  • Produce a balanced redox equation from an unbalanced one in either acidic or basic media

• Wetland Soils

  • Nutrient cycling in lakes and freshwater wetlands depends heavily on redox conditions.
  • Redox potential, or reduction potential , is used to express the likelihood of an environment to receive electrons and therefore become reduced.
  • The oxidized environment has high redox potential, whereas the reduced environment has a low redox potential.
  • The redox potential is controlled by the oxidation state of the chemical species, pH and the amount of oxygen (O2) there is in the system.
  • This equation will tend to move to the right in acidic conditions which causes higher redox potentials to be found at lower pH levels.

• Free Energy and Cell Potential

  • In a galvanic cell, where a spontaneous redox reaction drives the cell to produce an electric potential, the change in Gibbs free energy must be negative.
  • In a galvanic cell, where a spontaneous redox reaction drives the cell to produce an electric potential, the change in Gibbs free energy must be negative.
  • Calculate the change in Gibbs free energy of an electrochemical cell where the following redox reaction is taking place:
  • Because the change in Gibbs free energy is negative, the redox process is spontaneous.
  • Calculate the change in Gibbs free energy of an electrochemical cell, and discuss its implications for whether a redox reaction will be spontaneous

• Electron Donors and Acceptors

  • In other words, they correspond to successively smaller Gibbs free energy changes for the overall redox reaction Donor → Acceptor.
  • Since electron transport chains are redox processes, they can be described as the sum of two redox pairs.
  • For example, the mitochondrial electron transport chain can be described as the sum of the NAD+/NADH redox pair and the O2/H2O redox pair.
  • The redox potential of the acceptor must be more positive than the redox potential of the donor.
  • The associated redox reaction, which is thermodynamically favorable in nature, is thermodynamically impossible under "standard" conditions.

• Oxidation of Phenols

  • The redox equilibria between the dihydroxybenzenes hydroquinone and catechol and their quinone oxidation states are so facile that milder oxidants than chromate (Jones reagent) are generally preferred.
  • The position of the quinone-hydroquinone redox equilibrium is proportional to the square of the hydrogen ion concentration, as shown by the following half-reactions (electrons are colored blue).