Electrochemistry

Question 1

What is oxidation?

Answer 1

The loss of electrons

Question 2

What is reduction?

Answer 2

The gain of electrons

Question 3

What are electrochemical cells?

Answer 3

Cells that use the transfer of electrons during redox reactions to produce electrical energy

Question 4

What are electrochemical cells made of?

Answer 4

Two half cells that are connected via an external circuit like a conducting wire. Electrons flow accross the wire
A salt bridge, where filter paper is soaked in potassium chloride or potassium nitride, allowing ions to flow accross.
Under standard conditions

Question 5

What are the standard conditions that electrochemical cells are under?

Answer 5

All solitions are 1moldm3
100kpa
298K

Question 6

Describe a standard copper zinc cell

Answer 6

Tye copper electrode is the positive electrode and on the right, the zinc electrode is the negative and on the left. Electrons flow from zinc to copper

Question 7

Descrobe the flow lf electrons in an electrochemical cell, and where does oxidation and reeuction occur?

Answer 7

Electrons flow from the negative to positive electrode. Oxidation occurs at the negative electrode. Reeuctipn at the positive

Question 8

What is a half cell?

Answer 8

A cell that contains two species of the same element, with different oxidation states.

Question 9

What is the standard electrode potential?

Answer 9

The e.m.f of a half cell compared to a standard hydrogen half cell, under standard contitions

Question 10

What is the primary standard ekectrode potential?

Answer 10

The standard hydrogen electrode potential (0.00V) and is used to determine the potential lf other half cells

Question 11

Describe a hydrogen half cell

Answer 11

Contains 100kpa H2 gass
1 moldm3 H+ ions (HCl)
Pt electrode

Question 12

Describe the conventional representation of an electrochemical cell

Answer 12

A double verticle line indicates a salt bridge
A single,e verticle line indicates a phase boundary (change in state)
The species with the highest oxidation state for each half cell is written next to the salt bridge
Positive electrode is on the right and negative on the left (unless hydrigen is used in which case hydrogen is always on the left)

Question 13

What happens in an electrochemical cell if a half cell contains species whoch are both aqueous solutions?

Answer 13

A Pt electrode is used to ensure there is both an oxidised and reeuces species in the half cell

Question 14

In the electrochemical series, which species are the best reducing agents?

Answer 14

Species with the most negative potential on the right hand side

Question 15

In the electrochemical series, which are the best oxidising agents?

Answer 15

The species with the highest potential on the left hand side

Question 16

How do you calculate an electrochemical cells potential when hydrogen is not used?

Answer 16

Potential of the right species- potential of the left species

Question 17

When reading an electrochemical series, how do you know is two element will react with eachother?

Answer 17

Pne must be the best oxidising reagent, and another must be a best reducing reagent.
A species must be more negative than another to be able to reduce it
Or a species must be more positive than another to oxidise it