Term
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Definition
| Separation of a mixture based on differences in solutes' attraction for a moving/mobile phase and its attraction for the stationary/solid |
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Term
| Separation is based on mixture characteristics such as |
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Definition
Charge (acid/ base-polar/nonpolar)
Size
Solubility
Weight (mass)
Rate of diffusion/migration
Ionic strength
Volatility |
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Term
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Definition
| Consists of a solid (or solid coated with a liquid) which remains in a fixed position |
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Term
| What are examples of solid phase objects? |
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Definition
| Paper, alumin gel, cellulose acetate, polymers |
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Term
| Mobile Phase/ Moving Phase |
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Definition
| Consists of a liquid or gas which moves through the stationary phase carrying the mixture through the system |
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Term
| What are examples of the mobile/moving phase? |
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Definition
| Helium gas, organic solvents, buffers, ionic solution |
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Term
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Definition
| Determined by physical properties of the mixture, interaction of these properties between the mobile and stationary phase. High pressure pump (HPLC) |
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Term
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Definition
| Time it takes for the substance of interest to migrate to an endpoint or be eluted from the column |
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Term
| Ratio of fronts (Rf) can be calculated by |
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Definition
| Distance compound moves/ distance solvent moves |
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Term
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Definition
| Time of elution for compound/ Mobile phase time of elution |
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Term
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Definition
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Term
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Definition
| Collect each substance determined by photometric means. Analysis of peak height (strip chart recorder) |
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Term
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Definition
| How well can you separate the components of a mixture is the distance between consecutive peaks. Depends on the separation ability of the system and the rate of migration |
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Term
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Definition
| Equilibrium points between the solute in the mobile phase |
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Term
| Height Equivalent Theoretical Plates (HETP) |
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Definition
| Estimates the efficiency for a given length of a column |
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Term
| Height equivalent theoretical plates can be calculated by |
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Definition
H =L/N
L= column length
N= # of theoretical plates |
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Term
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Definition
Classification based on liquid mobile phase
Involves column, HPLC and TLC |
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Term
| What does the stationary phase of liquid chromatography contain? |
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Definition
Adsorptive molecules
Silica gel
Charcoal |
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Term
| Liquid chromatography partition |
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Definition
Liquid/liquid
Solubility between two immiscible liquids |
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Term
| Normal phase of liquid chromatography |
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Definition
Polar solvent on the stationary phase
Nonpolar liquid mobile phase |
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Term
| Reverse phase of liquid chromatography |
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Definition
Nonpolar stationary phase
Polar liquid mobile phase |
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Term
| Small particles stay in the column faster compared to large particles that |
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Definition
| Travel faster through the column due to their size/weight |
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Term
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Definition
| Separation based on charge (anions/cations) |
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Term
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Definition
| Positive charges covalently bonded to stationary phase resin |
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Term
| Cation (positive ion) exchange |
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Definition
| Stationary phase carries a negative charge bonded to it |
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Term
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Definition
| Stationary phase contains ligands, haptens, enzymes or antibodies capable of binding |
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Term
| How do you perform gas chromatography? |
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Definition
Place known sample in column
Obtain readout
Put unknown sample in
Obtain readout
Compare the two readouts |
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Term
| Gas chromatography detectors |
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Definition
Thermal conductivity
Hydrogen flame ionization detectors
Alkali flame ionization
Electron capture |
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Term
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Definition
Wheatstone bridge setup
Two filaments are exposed to carrier gas alone
Two filaments are exposed to gas plus sample
Change in temperature results in change in resistance |
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Term
| Hydrogen flame ionization |
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Definition
| Organic compounds burned in the flame produce electrons which are attracted to an anode causing a current to flow. The change in current is amplified |
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Term
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Definition
Beta emitters ionize the carrier gas and a standing current develops across the opening
Any halogenated compounds in the sample will be captured and the standing electrons cause a change in current |
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Term
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Definition
| Separation of charged molecules by differences in their rate of migration in an electric field |
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Term
| What samples are used in electrophoresis? |
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Definition
Serum
RBC hemolysates
Urine
CSF |
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Term
| What is the purpose of electrophoresis? |
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Definition
| To separate the constituent protein into major fractions. Once it is separated, selective staining can be done to visualize bands |
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Term
| Electrophoresis is used for |
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Definition
Proteins
Lipoproteins
Enzymes |
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Term
| Since each protein is made of many amino acids with ionizable groups the net amount or surface charge of the molecule is |
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Definition
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Term
| What determine the overall charge on the amphoteric protein molecule? |
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Definition
The PI (isoelectric point)
pH |
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Term
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Definition
| The point at which the protein is neutral |
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Term
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Definition
| Do not migrate in an electric field. |
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Term
| If the pH of a solution is higher or more basic than the PI the protein carries what? |
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Definition
| A net negative charge and migrates towards the anode |
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Term
| If the pH of the solution is lower or more acidic than the PI the protein carries what? |
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Definition
| A net positive charge and migrates toward the cathode |
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Term
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Definition
| Depends not only on the net charge of the molecule but also on the size and shape of the molecule, the strength of the electric field, the porosity viscosity and temperature of the support media and electroendosmosis |
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Term
| What are some issues of migration rate? |
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Definition
Diffusion of the protein into the gel or support media increases with time, causing poor resolution of the bands
Excess heat denatures proteins (no migration) |
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Term
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Definition
| A buffer flow effect that results in displacement of the separated proteins towards the cathode |
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Term
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Definition
| Negatively charged support media that attracts positive charged buffer ions which migrate towards the cathode when exposed to an electric field |
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Term
| At a pH of 8.6 proteins are what? |
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Definition
| Negative (anions) and migrate toward the anode against buffer flow |
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Term
| What are the components of an electroendosmosis system? |
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Definition
Molecules to be separated (proteins and nucleic acids)
Support medium (gel-Polyacrylamide or Agarose)
Buffer system
DC power source |
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Term
| What are some factors that influence mobility? |
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Definition
Properties of the molecules to be separated (molecular size, molecular shape, molecular charge)
Properties of the system (electric field strength, porosity of the support medium, conductivity of the buffer, pH of the buffer) |
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Term
| Mobility is proportional to what? |
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Definition
Charge/molecular weight
Field strength |
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Term
| Mobility is inversely proportional to what? |
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Definition
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Term
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Definition
| The amount of energy per charge available to move electrons from one point to another in a circuit |
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Term
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Definition
| The rate of charge flow and is measured in amperes |
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Term
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Definition
| The opposition to current and is measured in ohms. |
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Term
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Definition
I=V/R
I= current
V= voltage
R= resistance |
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Term
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Definition
| Current is directly proportional to voltage and inversely proportional to resistance |
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Term
| Electrochemical processes are oxidation-reduction reactions in which |
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Definition
| The energy released by a spontaneous reaction is converted to electricity or electrical energy is used to cause a nonspontaneous reaction to occur |
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Term
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Definition
| Loss of electrons by a species; increase in oxidation number; increase in oxygen |
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Term
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Definition
| Gain of electrons; decrease in oxidation number; decrease in oxygen; increase in hydrogen |
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Term
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Definition
| Electron acceptor; species is reduced |
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Term
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Definition
| Electron donor; species is oxidized |
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Term
| Reduction can't occur without what? |
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Definition
| Oxidation to provide the electrons |
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Term
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Definition
| The charge an atom would have in a molecule if electrons were completely transferred |
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Term
| Free elements (uncombined elements) have an oxidation number of |
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Definition
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Term
| In monatomic ions, the oxidation number is equal to what? |
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Definition
The charge of the ion
Ex. Fe 3+ = oxidation number of 3 |
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Term
| Oxidation number of oxygen is usually what? |
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Definition
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Term
| Oxidation number of oxygen in H2O2 and O2 2- is what? |
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Definition
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Term
| The element or compound that is reduced is the |
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Definition
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Term
| The element or compound that is oxidized is the |
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Definition
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Term
| Half-reaction method of balancing oxidation-reduction equations |
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Definition
1. Assign oxidation numbers to determine what is reduced and what is oxidized
2. Write the oxidation and reduction half-reactions
3. Balance each half reactions
4. Multiply the half reactions by integers so that the electrons gained and lost are the same.
5. Add the half-reactions, subtracting things that appear on both sides
6. Make sure the equation is balanced according to mass
7. Make sure the equation is balanced according to charge |
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Term
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Definition
| The field of electroanalytical chemistry in which potential is measured under the conditions of no current flow. |
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Term
| Once the potential has been measures in potentiometry it may be used to |
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Definition
| Determine the analytical quantity of interest, generally the concentration of some component of the analyte solution |
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Term
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Definition
| Chemical analysis by techniques which involve measuring electric currents |
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Term
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Definition
| Method for determining the quantity of a substance based on a strict proportionality between the extent of a chemical charge and the quantity of electricity involved |
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Term
| The quantity of the material to be analyzed using coulometry can be determined directly by |
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Definition
| Depositing the substance on an electrode |
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Term
| Faraday's 1st law of electrolysis |
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Definition
| The mass of a substance altered at an electrode during electrolysis is directly proportional to the quantity of electricity transferred at that electrode. |
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Term
| Faraday's 2nd law of electrolysis |
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Definition
| For a given quantity of electricity, the mass of an elemental material altered at an electrode is directly proportional to the element's equivalent weight. |
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Term
| Faraday's law can be summarized by |
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Definition
m= (Q/F) (M/2)
m= mass of the substance liberated at an electrode in grams
Q= the total electric charge passed through the substance |
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Term
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Definition
| An electrochemical technique for identifying and estimating the concentration of reducible elements in an electrochemical cell by means of the dual measurement of the current flowing through the cell and the electrical potential at which each element is reduced. |
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Term
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Definition
| Consists of 2 half cells and a salt bridge |
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Term
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Definition
| The difference in electrical potential between the anode and the cathode |
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Term
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Definition
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Term
| Electromotive force (EMF) |
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Definition
| The potential between the anode and the cathode in a cell |
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Term
| What is another name for electromotive force? |
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Definition
Cell potential
Designated Ecell |
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Term
| The strongest oxidizers have the most |
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Definition
| Positive reduction potentials |
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Term
| The strongest reducers have the most |
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Definition
| Negative reduction potentials |
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Term
| The greater the difference between the two the greater the |
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Definition
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Term
| Ion-selective electrode (ISE) or specific ion electrode (SIE) |
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Definition
| A transducer that converts the acitivty of a specific ion dissolved in a solution into an electrical potential which can be measured by a voltmeter or pH meter |
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Term
| According the Nernst equation, the voltage is theoretically dependent upon what? |
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Definition
| The logarithm pf the ionic activity |
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Term
| What are the main types of ion-selective membrane used in ion-selective electrodes? |
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Definition
Glass
Crystalline
Ion exchange resin and enzyme electrode |
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