Redox Reactions and Electrode Potentials

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• Created by: J.E.C.
• Created on: 21-04-14 16:41
The enrgy given out from an electrochemical cell becomes available as...?
Electrical energy
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The voltage measures the...?
Potential difference between the two terminals
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The higher the current drawn, the ___ the voltage the cell may give?
Lower
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To compare cells and half-cells we can measure ___ between the terminals of the cell when...? Represented by..?
p.d., no current flows. Ecell
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To measure Ecell you need to use a __ __ __ so that almost no current flows, then record the...?
High resistance voltmeter, maximum potential difference between the electrodes of the two half-cells.
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The potential difference is a measure of how much each electrode is tending to...?
Release or accept electrons
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Electric current is..?
Flow of charge, measured in Amps.
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One amp is...?
A flow of charge of one coulomb per second.
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The voltage of the cell tells you the...?
Number of joules of energy transferred whenever one coulomb of charge flows around the circuit.
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1 V =
1 J Cֿ ¹
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What 3 things would you include when drawing a simple half cell?
Metal ***** (contains the atoms), Solution of metal ions (contains the ions of that metal)
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If the atoms in the metal ***** release electrons the ***** becomes...? If the ions in the solution then accept electrons, what will be reformed?
Negatively charged relative to the solution. The metal atoms.
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An equilibrium is set up if...?
The ions are beinf produced at the same rate that they are being turned back into metal atoms.
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The position of the equilibrium determines...?
The size of the potential difference between the metal ***** and the solution of the metal ions.
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The further to the right the equilibrium lies, the...?
Greater the tendency of the electrode to accept electrons, and the more positive the electrode potential.
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What would you use as a salt bridge to connect two half cells?
A ***** of filter paper soaked in saturated potassium nitrate(V) solution.
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It is sometimes called an ion bridge because the current...?
Is carried by the movement of ions, not electrons.
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An electrochemical cell consists of..?
Two half-cells connected by a salt-bridge.
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A standard Hydrogen half-cell is often used as a reference, the half-reaction for this half-cell is...?
2H+(aq) + 2e- --> H2(g)
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Give the 3 standard conditions associated with taking electrode potentials?
298K, 1.00 moldmֿ ³, 1 atm
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The standard electrode potential (Eθ) of a half cell is...?
The potential difference between it and a standard hydrogen half-cell.
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The more positive the standard electrode potential, the greater the tendency to ___ electrons?
Accept
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The Ecell value is simply the voltage difference between the two half-cells and is always positive so always subtract the __ positive value from the __ positive value?
less, more
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Electrons in the external circuit flow from the __ to the __ terminal?
Negative, positive
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Give the half-reaction for iron as part of rusting?
Fe2+(aq) + 2e- --> Fe(s)
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Give the half-reaction for oxygen as part of rusting?
½O2 (g) + H2O (l) + 2eֿ --> 2OH ֿ(aq)
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The reduction of oxygen occurs at the more ___ potential, so electrons flow to...?
Positive, to the half-cell in which the iron is oxidised to iron(II) ions.
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Iron is oxidised and Fe2+ ions pass...?
Into solution
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What determines which regions of the metal surface are sites of reduction and which are sites of oxidation?
The concentration of dissolved oxygen in the water droplet.
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At the edges of the droplet, where the concentration of dissolved oxygen is ___, oxygen is...?
Higher, reduced to hydroxide ions
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Where do the electrons needed to reduce the oxygen come from?
From the oxidation of iron at the centre of the water droplet, where the concentration of dissolved oxygen is low.
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The electrons released flow in...?
The metal surface to the edges of the droplet.
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Other cards in this set

Card 2

Front

The voltage measures the...?

Back

Potential difference between the two terminals

Card 3

Front

The higher the current drawn, the ___ the voltage the cell may give?

Card 4

Front

To compare cells and half-cells we can measure ___ between the terminals of the cell when...? Represented by..?

Card 5

Front

To measure Ecell you need to use a __ __ __ so that almost no current flows, then record the...?