Examples of chemical potential in the following topics:
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- Each chemical species has an electrochemical potential (quantity with units of energy) at any given location, which represents how easy or difficult it is to add more of that species to that location.
- If possible, a species will move from areas with higher electrochemical potential to areas with lower electrochemical potential.
- We say the ions have electric potential energy, and are moving to lower their potential energy.
- We say that the sugar molecules have a "chemical potential," which is higher in the high-concentration areas, and the molecules move to lower their chemical potential.
- These two examples show that an electrical potential and a chemical potential can both give the same result: a redistribution of the chemical species.
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- Just as in mechanics, where potential energy is defined as capacity to do work, similarly different potentials have different meanings.
- Gibbs energy (also referred to as ∆G) is also the chemical potential that is minimized when a system reaches equilibrium at constant pressure and temperature.
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- Reduction potential (also known as redox potential, oxidation/reduction potential, or Eh) measures the tendency of a chemical species to acquire electrons and thereby be reduced.
- Reduction potential is measured in volts (V) or millivolts (mV).
- Each species has its own intrinsic reduction potential.
- Historically, many countries, including the United States and Canada, used standard oxidation potentials rather than reduction potentials in their calculations.
- However, because these can also be referred to as "redox potentials," the terms "reduction potentials" and "oxidation potentials" are preferred by the IUPAC.
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- The standard potential of an electrochemical cell requires standard conditions for all of the reactants.
- When reactant concentrations differ from standard conditions, the cell potential will deviate from the standard potential.
- In the late 19th century, Josiah Willard Gibbs formulated a theory to predict whether a chemical reaction would be spontaneous based on free energy:
- In chemistry, a reaction quotient is a function of the activities or concentrations of the chemical species involved in a chemical reaction.
- Discuss the implications of the Nernst equation on the electrochemical potential of a cell
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- Noble gases are the six chemical elements of Group 18 of the periodic table, being monatomic and (with very limited exceptions) inert.
- The noble gases are a group of chemical elements that make up Group 18 on the periodic table.
- Noble gases have the largest ionization potential among the elements of each period.
- This reflects the stability of their electron configuration and points again to their relative lack of chemical reactivity.
- The noble gases have the largest ionization potential for the elements in their respective periods.
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- When materials deteriorate by chemical processes, the materials are said to corrode.
- How susceptible a particular metal is to corrosion can be determined by its reduction potential.
- The higher a metal's reduction potential, the less likely it is to be oxidized.
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- Depending on the reduction potential of the metal, the reactivity of organometallic compounds varies markedly, the most reactive requiring low to moderate temperatures and inert conditions (atmosphere and solvents) for preparation and use.
- In general, the reactivity parallels the ionic character of the carbon-metal bond, which may be estimated from the proton and carbon chemical shifts of methyl derivatives.
- All these metals have strong or moderate negative reduction potentials, with lithium and magnesium being the most reactive.
- Although the formulas drawn here for the alkyl lithium and Grignard reagents reflect the stoichiometry of the reactions and are widely used in the chemical literature, they do not accurately depict the structural nature of these remarkable substances.
- Since magnesium halides are moderate Lewis acids, their presence in solution may influence the outcome of certain chemical reactions.
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- Lone electrons cannot usually pass through the electrolyte; instead, a chemical reaction occurs at the cathode that consumes electrons from the anode.
- Here, the electrode reactions convert chemical energy to electrical energy.
- Historically, oxidation potentials were tabulated and used in calculations, but the current standard is to only record the reduction potential in tables.
- If a problem demands use of oxidation potential, it may be interpreted as the negative of the recorded reduction potential.
- Positive potential is more favorable in this case.
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- Recall that standard cell potentials can be calculated from potentials E0cell for both oxidation and reduction reactions.
- A positive cell potential indicates that the reaction proceeds spontaneously in the direction in which the reaction is written.
- Conversely, a reaction with a negative cell potential proceeds spontaneously in the reverse direction.
- A single vertical line ( | ) is drawn between two chemical species that are in different phases but in physical contact with each other (e.g., solid electrode | liquid with electrolyte).
- The phase of each chemical (s, l, g, aq) is shown in parentheses.
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- A fuel cell is a device that converts the chemical energy from fuel into electricity via a chemical reaction with oxygen or another oxidizing agent.
- Individual fuel cells produce relatively small electrical potentials, about 0.7 volts, so cells are "stacked," or placed in series, to increase the voltage.
- Two chemical reactions occur at the interfaces of the three different segments.
- Fuel cells convert the chemical energy from fuel into electricity via a chemical reaction with oxygen or another oxidizing agent.
- Fuel cells are a potential energy source for cars that do not run on gasoline.