Half Reactions
Cells
Oxidation Numbers
200

What is a Redox Reaction?

  1. Chemical reactions where one atom loses electrons while another atom gains electrons.

  2. The transfer of electrons
200

What is the purpose of the salt bridge in an electrochemical cell?

Transfer mobile ions

200

What is the oxidation of a lone element that is not in a compound?

A lone element that is not in a compound always has an oxidation number of zero (0).

400

What do reduction agents and oxidizing agents do?

  1. RA: a substance that donates electrons to another species / OA: a substance that removes electrons from another species

  2. RA: Oxidation / OA: Reduction
400

In which direction do electrons flow in a voltaic cell?

Anode → Cathode

400

Determine the oxidation state of sulfur in Na2SO4

S = -6

600

Identify the species being reduced and the species being oxidized: Ag + H2S → Ag2S + H2

Reduced: H / Oxidized: Ag

600

Name 3 differences between voltaic and electrolytic cells.

  1. V: Contains 2 beakers / E: Contains 1 beaker

  2. V: Contains Salt Bridge / E: No Salt Bridge

  3. V: No Power Source / E: Contains Power Source

  4. V: No Electrolyte Solution / E: Contains Electrolyte Solution

  5. V: Contains Volt Meter or Light / E: No Volt Meter or Light

  6. V: Chemical energy → electric energy / E: Electrical energy → chemical energy

600

When is Hydrogen not +1?

When it’s combined with a metal.

800

Identify the spectator ion: 2KBr + I2 → Br2 + 2KI

K+1

800

Which energy change occurs in an operating voltaic cell?

Chemical energy → electric energy

800

When is the charge of Oxygen not -2?

When combined with fluorine (OF) or the peroxide ion (O2).

1000

What is a metal that is more easily reduced than iron but less easily reduced than aluminum?

  1. Ti

  2. Mn

  3. Zn

  4. Cr

1000

In the voltaic cell, what is the direction of the flow of electrons?

Mg(s) → Ni(s)

1000

Determine the oxidation number of chromium in K2Cr2O7

Cr = +6 

M
e
n
u