Electricity electron flow

Is there an acceptable proposal by which this intermediate electricity (electron flow) developed from two differentkinds of sites in the mitochondrion (see Fig. 14.41), is able to convert ADP to ATP 17 (ATP has to proceed from the mitochondrion to the nearest point at which its energy is needed, e.g., to work muscles.)... 

Metals are also good conductors of electricity. Electrons flow easily between the atoms of a metal. An electrical current at one end of a metal wire quickly passes through to the other end. 

If a gas such as argon is held in a glass envelope that has two electrodes set into it (Figure 6.4), application of an electric potential across the electrodes leads to changes in the gas as the electrons flow from the cathode (negative electrode) to the anode (positive electrode). This passage of electrons... 

Taken as a group, PV cells comprise soHd-state devices in which photons of light coUide with atoms and transfer thek energy to electrons. These electrons flow into wkes that ate connected to the cells, thereby providing current to electrical loads. 

When two conducting phases come into contact with each other, a redistribution of charge occurs as a result of any electron energy level difference between the phases. If the two phases are metals, electrons flow from one metal to the other until the electron levels equiUbrate. When an electrode, ie, electronic conductor, is immersed in an electrolyte, ie, ionic conductor, an electrical double layer forms at the electrode—solution interface resulting from the unequal tendency for distribution of electrical charges in the two phases. Because overall electrical neutrality must be maintained, this separation of charge between the electrode and solution gives rise to a potential difference between the two phases, equal to that needed to ensure equiUbrium. 

Reaction centers convert light energy into electrical energy by electron flow through the membrane... 

To exploit the energy produced in this reaction, the half reactions are separated. The oxidation reaction is carried out at a zinc electrode (Zn Zir + 2 electrons) and the reduction reaction is carried out at a copper electrode (Cu"" + 2 electrons Cu metal). Electrons flow through a metal wire from the oxidizing electrode (anode) to the reducing electrode (cathode), creating electric current that can be harnessed, for example, to light a tungsten bulb. 

Electricity is the result of electrons flowing through a conductor, or wire. Current is the flow of electricity when a pressure or voltage is applied to the conductor. 

Solid-state electronic devices such as diodes, transistors, and integrated circuits contain p-n junctions in which a p-type semiconductor is in contact with an n-type semiconductor (Fig. 3.47). The structure of a p-n junction allows an electric current to flow in only one direction. When the electrode attached to the p-type semiconductor has a negative charge, the holes in the p-type semiconductor are attracted to it, the electrons in the n-type semiconductor are attracted to the other (positive) electrode, and current does not flow. When the polarity is reversed, with the negative electrode attached to the n-type semiconductor, electrons flow from the n-type semiconductor through the p-type semiconductor toward the positive electrode. 

An electrical potential shifts the energy levels in a metal. The arrows show the direction of electron flow. 

Figure 10-53 shows band-gap diagrams of n-type and p-type semiconductors. Electrical current flows in a doped semiconductor in the same way as current flows in a metal (see Figure 10-501. Only a small energy difference exists between the top of the filled band and the next available orbital, so the slightest applied potential tilts the bands enough to allow electrons to move and current to flow.

Redox reactions can proceed by direct transfer of electrons between chemical species. Examples include the rusting of iron and the metabolic breakdown of carbohydrates. Redox processes also can take place by indirect electron transfer from one chemical species to another via an electrical circuit. When a chemical reaction is coupled with electron flow through a circuit, the process is electrochemical. Flashlight batteries and aluminum smelters involve electrochemical processes. 

Electrochemistry is the coupling of a chemical redox process with electron flow through a wire. The process represented in Figure 19-7 is electrochemical because the redox reaction releases electrons that flow through an external wire as an electrical current. On the other hand. Figure 19-5 shows a redox process that is not electrochemical, because direct electron transfer cannot generate an electrical current through a wire. 

Water flows down a spillway from higher to lower gravitational potential. Electrons flow downhill through a wire from higher to lower negative electrical potential. 

In a galvanic cell, electrons flow downhill from a region of higher electrical potential to a region of lower electrical potential. 

The difference in electrical potential between two electrodes is the cell potential, designated E and measured in volts (V). The magnitude of E increases as the amount of charge imbalance between the two electrodes increases. For any galvanic cell, the value of E and the direction of electron flow can be determined experimentally by inserting a voltmeter in the external circuit. 

Defining a reference value for the SHE makes it possible to determine E ° values of all other redox half-reactions. As an example. Figure 19-14 shows a cell in which a standard hydrogen electrode is connected to a copper electrode in contact with a 1.00 M solution of C U . Measurements on this cell show that the SHE is at higher electrical potential than the copper electrode, indicating that electrons flow from the SHE to the Cu... 

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. 

The silver-zinc cell is a storage battery After discharge, it can be recharged by forcing through it an electric cnrrent in the reverse direction. In this process the two electrode reactions (19.3) and (19.4) as well as the overall reaction (19.2) go from right to left electrons flowing in the sense of arrow r in Fig. 19.1. 

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