electrode potentials Flashcards

1
Q

what is the E nought value?

A

how easily the half cell loses electrons (is oxidised)

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2
Q

describe how electrode potential equations are written

A
  • in reduced form
  • reduction is always the forward direction
  • electrons on the LEFT
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3
Q

how are E nought values used to decide whether something is oxidised or reduced?

A

most negative = oxidation
most positive = reduction

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4
Q

use the following equations & values to decide what is oxidised/reduced

Zn2+ + 2e- –> Zn (-0.76)
Cu2+ + 2e- –> Cu (+0.34)

A

Zn is most negative so is oxidised = reducing agent

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5
Q

use the following equations to create an overall equation

Zn2+ + 2e- –> Zn (-0.76)
Cu2+ + 2e- –> Cu (+0.34)

A

Zn is oxidised so must be flipped so it is in reduced form

Zn –> Zn2+ + 2e-
Zn + Cu2+ <–> Zn2+ + Cu

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6
Q

what standard reference are E nought values measured against?

A

standard hydrogen electrode (SHE)

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7
Q

what is the value of the SHE?

A

0

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8
Q

what are the standard conditions for SHE?

A

1moldm-3
298K
100kPa

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9
Q

where is the 1 mole of H+ ions obtained from for creating a SHE?

A

1mole HCl or 1/2mole H2SO4

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10
Q

state the calculation for standard cell potential (overall E nought value)

A

Enought reduced - Enought oxidised

(pos - neg)

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11
Q

what is cell notation?

A

the simplified setup of a cell using vertical lines

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12
Q

where is the negative half cell positioned in cell notation?

A

left of double line

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13
Q

what do single lines represent in cell notation?

A

physical state changes

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14
Q

state the general cell notation

A

reduced | Zn2+ || Cu2+ | Cu

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15
Q

how are 2 aq ions separated in cell notation

A

with a comma

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16
Q

define ‘standard electrode potential’

A

the emf of a half cell compared with a standard hydrogen half cell under standard conditions

17
Q

what experimental method would be used to measure standard electrode potential of Cu?

A
  • hydrogen gas
  • platinum electrode
  • 1moldm-3 H+ ions
18
Q

deduce the direction of electron flow when inert electrodes are connected

A

left to right