E.m.f. of a cell depends upon the material of electrodes and electrolyte used in the cell. It is independent of shape of electrodes, distance between electrodes and the amount of electrolyte.
What determines the emf of a cell?
The cell potential or EMF of the electrochemical cell can be calculated by taking the values of electrode potentials of the two half – cells. … By taking into account the oxidation potential of anode and reduction potential of cathode. By considering the reduction potentials of both electrodes.
How does temperature affect the emf of a cell?
ABSTRACT: The Emf of a cell is measured at several temperatures. … The emf produced by an electrochemical reaction will generally change with temperature. The free energy change can be found directly from the measured emf, while the entropy change can be found from the slope of the plot of the emf vs.
Why does the emf of a cell decrease over time?
The electric potential increases the emf of the battery due to the chemical reactions doing work on the charges. There is a decrease in the electric potential in the battery due to the internal resistance.
Is EMF the same as cell potential?
(1) “The difference in potentials of the two half – cells of a cell known as electromotive force (emf) of the cell or cell potential.” The difference in potentials of the two half – cells of a cell arises due to the flow of electrons from anode to cathode and flow of current from cathode to anode.
What is standard EMF of cell?
Standard emf of a cell is the difference in the standard reduction potentials of cathode and anode when no current flows through the cell. For the relationship between standard emf (E∘cell) are equilibrium constant(Kc), consult Section 9.11.
Why EMF of the cell is always positive?
By convention, when a cell is written in shorthand notation, its emf is given a positive value if the cell reaction is spontaneous. That is, if the electrode on the left forces electrons into the external circuit and the electrode on the right withdraws them, then the dial on the voltmeter gives the cell emf.
Why does EMF decrease with temperature?
as the reactants in the cell approach the equilibrium concentrations the voltage drops to zero. … lnK decreases with temperature as eventually the reaction is at equilibrium at some temperature and the voltage is zero. This suggests there is a temperature of maximum voltage.
How does temperature affect voltaic cells?
The effect of the temperature of a voltaic cell on the voltage that it generates. An increase in the temperature of a voltaic cell can either increase or decrease the voltage that it generates, depending on the magnitude of the reaction quotient, Q.
How does temperature affect potential difference?
As the temperature rises, the resistance of the thermistor decreases, so the potential difference across it decreases. This means that potential difference across the resistor increases as temperature increases. This is why the voltmeter is across the resistor, not the thermistor.
What is the difference between voltage and EMF?
The EMF is the measure of energy supply to each coulomb of charge, whereas the voltage is the energy use by one coulomb of charge to move from one point to another. … The EMF is generated by the electrochemical cell, dynamo, photodiodes, etc., whereas the voltage is caused by the electric and magnetic field.
What is the formula for induced emf?
An emf induced by motion relative to a magnetic field is called a motional emf. This is represented by the equation emf = LvB, where L is length of the object moving at speed v relative to the strength of the magnetic field B.
Why emf is not a force?
The word “force” is somewhat misleading, because EMF is not a force, but rather a “potential” to provide energy. The term EMF is retained because of historical reasons, and is useful to distinguish between voltages that are generated and energy that is lost to resistors.11 мая 2018 г.
Can you have negative EMF?
The voltage is not negative, always. The negative sign in Faraday’s law (Lenz’s law) does not mean that the EMF (or current) always points in some “negative” direction. It means that the current always flows in a way to oppose the change in flux, which is nicely illustrated in that video clip.
What is the difference between electrode potential and EMF?
It is the potential difference between two electrodes when no current is flowing in the circuit. It is the difference of the electrode potentials of the two electrodes when the cell is under operation. It is always less then the maximum value of voltage which the cell can deliver. …
What is EMF in simple words?
Electromotive force, abbreviation E or emf, energy per unit electric charge that is imparted by an energy source, such as an electric generator or a battery. … Electromotive force is the characteristic of any energy source capable of driving electric charge around a circuit.27 мая 2020 г.