Mole of electrons

The existence of the hydride ion is shown by electrolysis of the fused salt when hydrogen is evolved at the anode. If calcium hydride is dissolved in another fused salt as solvent, the amount of hydrogen evolved at the anode on electrolysis is 1 g for each Faraday of current (mole of electrons) passed, as required by the laws of electrolysis. 

Moles of electrons lost Mole reducing agent... 

Faraday Constant (F) the quantity of electric charge involved in the passage of one Avagadro number (or one mole) of electrons. The value of F (universal) is 96 485 C mol . ... 

The approach used in Example 18.5 to find the number of moles of electrons transferred, n, is generally useful. What you do is to break down the equation for the cell reaction into two half-equations, oxidation and reduction. The quantity n is the number of electrons appearing in either half-equation. 

In this equation, E is the cell voltage, E° is the standard voltage, n is the number of moles of electrons exchanged in the reaction, and Q is the reaction quotient. Notice that—... 

An electrolysis experiment is performed to determine the value of the Faraday constant (number of coulombs per mole of electrons). In this experiment, 28.8 g of gold is plated out from a AuCN solution by running an electrolytic cell for two hours with a current of 2.00 A. What is the experimental value obtained for the Faraday constant ... 

Faraday constant The constant that gives the number of coulombs equivalent to one mole of electrons 96480 C/mol e, 491,496... 

If you wish to replate a silver spoon, would you make it the anode or cathode in a cell Use half-reactions in your explanation. How many moles of electrons are needed to plate out 1.0 gram of Ag ... 

The coulomb is a unit of electric charge. Its magnitude can be appraised by its relation to the ampere. One ampere is an electric current of one coulomb of charge passing a point in a wire every second. One mole of electrons has, then, 96,500 coulombs of charge. In a wire carrying 10 amperes, it takes about two and one half hours for one mole of electrons to pass any point. 

How many electrons would be required to weigh one gram What would be the weight of a mole of electrons ... 

Using the reaction free energy AG, the cell voltage Aelectrons exchanged during an electrode reaction must be determined from the cell reaction. For the Daniell element (see example), two moles of electrons are released or received, respectively ... 

Lithium carbonate and hydrocarbon were identified in XPS spectra of graphite electrodes after the first cycle in LiPF6/EC-DMC electrolyte [104]. Electrochemical QCMB experiments in LiAsF6/EC-DEC solution [99] clearly indicated the formation of a surface film at about 1.5 V vs. (Li/Li+). However the values of mass accumulation per mole of electrons transferred (m.p.e), calculated for the surface species, were smaller than those of the expected surface compounds (mainly (CF OCC Li ). This was attributed to the low stability of the SEI and its partial dissolution. 

The quantity Q can be calculated from a knowledge of the chemical reaction. If n moles of electrons are transferred from cathode to anode during the chemical reaction11 and F is the quantity of electrical change carried by a mole of electrons, then... 

K.24 Silver tarnish is Ag2S. (a) When silver metal is tarnished, is it oxidized or reduced Answer this question by considering the oxidation numbers, (b) If a bar of silver is covered with 5.0 g of tarnish, what amount (in moles) of silver atoms was either oxidized or reduced (c) What amount (in moles) of electrons was transferred in part (b) ... 

The work done when an amount n of electrons (in moles) travels through a potential difference E is their total charge times the potential difference. The charge of one electron is — e the charge per mole of electrons is eNA, where NA is Avogadro s constant. Therefore, the total charge is —neNA and the work done is... 

Faraday s constant, F, is the magnitude of the charge per mole of electrons (the product of the elementary charge e and Avogadro s constant NA) ... 

The units of AG are joules (or kilojoules), with a value that depends not only on E, but also on the amount n (in moles) of electrons transferred in the reaction. Thus, in reaction A, n = 2 mol. As in the discussion of the relation between Gibbs free energy and equilibrium constants (Section 9.3), we shall sometimes need to use this relation in its molar form, with n interpreted as a pure number (its value with the unit mol struck out). Then we write... 

A note on good practice The value of n depends on the balanced equation. Check to ensure that n matches the number of moles of electrons transferred in the balanced equation. 

To determine the amount of electrons supplied by a given charge, we use Faraday s constant, F, the magnitude of the charge per mole of electrons (Section 12.4). Because the charge supplied is wF, where n is the amount of electrons (in moles), and Q = nF, it follows that... 

Step 2 Calculate the amount (in moles) of electrons supplied from Eq. 8, n = It/F. Use the stoichiometric relation from step 1 to convert n into the amount of... 

To understand why this is so, recall that cell potentials are analogous to altitude differences for water. Whether 10,000 or 20,000 L of water flows down a spillway, the altitude difference between the top and bottom of the spillway is the same. In the same way, multiplying a reaction by some integer changes the total number of moles of electrons transferred, but it does not change the potential difference through which the electrons are transferred. We return to this point in Section 19-1. 

The coefficients of any balanced redox equation describe the stoichiometric ratios between chemical species, just as for other balanced chemical equations. Additionally, in redox reactions we can relate moles of chemical change to moles of electrons. Because electrons always cancel in a balanced redox equation, however, we need to look at half-reactions to determine the stoichiometric coefficients for the electrons. A balanced half-reaction provides the stoichiometric coefficients needed to compute the number of moles of electrons transferred for every mole of reagent. 

Electricity is normally measured in units of charge, the coulomb (C), or as rate of electrical current flow, the ampere (A 1 A — 1 C/. ). The total amount of charge is the product of the current flow, symbolized by I, and the time for which this current flows Charge = It Just as molar mass provides the link between mass and moles, the Faraday constant provides the link between charge and moles. The number of moles of electrons transferred in a specific amount of time is the charge in coulombs divided by the charge per mole, F ... 

This is an electrochemical stoichiometry problem, in which an amount of a chemical substance is consumed as electrical current flows. We use the seven-step strategy in summary form. The question asks how long the battery can continue to supply current. Current flows as long as there is lead(IV) oxide present to accept electrons, and the batteiy dies when all the lead(IV) oxide is consumed. We need to have a balanced half-reaction to provide the stoichiometric relationship between moles of electrons and moles of Pb02. 

There are 250 g of Pb02, and the headlights draw 5.9 A of current. Equation links current with moles of electrons. Moles of electrons and moles of Pb02 are related as described by the balanced half-reaction, determined in Example ... 

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