Electrochemistry

What are conductors?

These are substances that allows an electric current to pass through. These can be solids, liquids, or solutions.

What are non-conductors?

These are substances that do not allow an electric current to pass through. They can be solids, liquids, gases, or solutions.

What are the properties of conductors and non-conductors?

1. Electrical conductivity 

2. Electron mobility 

3. Atomic/Molecular structure 

Describe the electrical conductivity of conductors

This is high

Describe the electrical conductivity of non-conductors

This is low

Describe the electron mobility of conductors

These are free

Describe the electron mobility of non-conductors

These are restricted 

Describe the atomic/molecular structure of conductors

These are metals

Describe the atomic/molecular structure of non-conductors

These are non-metals

What are the differences between metallic conductors and electrolytic conductors?

1. In metallic conductors, mobile electrons carry the electric current through the metal while in electrolytic conductors, mobile ions carry the electric current through the electrolyte. 

2. In metallic conductors, the metal remains chemically unchanged while in electrolytic conductors the electrolyte decomposes.  

What is an electrolyte?

This is a molten ionic compound or a solution containing ions that conducts electricity. 

What is a strong electrolyte?

This is an electrolyte that is fully ionized when dissolved in water. They have a high concentration of ions in solution

What is a weak electrolyte?

This is an electrolyte that is partially ionized when dissolved in water. They have a low concentration of ions in solution

What acids are examples of strong electrolytes?

Hydrochloric acid (HCl)

Nitric acid (HNO₃)

Sulphuric acid (H₂SO₄)

What acids are examples of weak electrolytes?

Carbonic acid (H₂CO₃)

Ethanoic acid (CH₃ COOH)

What alkalis are examples of strong electrolytes?

1. Potassium hydroxide solution

2. Sodium hydroxide solution

What alkalis are examples of weak electrolytes?

Aqueous Ammonia (NH₃ aq)

What salts are examples of strong electrolytes?

Molten sodium chloride (NaCl (l))

Sodium chloride solution (NaCl aq)

What salts are examples of weak electrolytes?

Molten potassium bromide (KBr (l))

Potassium bromide solution (KBr aq)

How can the strength of an electrolyte be tested?

This can be done using a simple circuit with a light bulb connected to a battery and two electrodes which are dipped in the electrolyte.

The greater the strength of the electrolyte, the more brightly the bulb will glow.

Define the term electrolysis

This is the decomposition of a compound by an electric current.

Define the term electrode

This is a rod that conducts electric current to and from the electrolyte

What is an anode?

This is a positive electrode

What is a cathode?

This is a negative electrode 

What are the conditions for electrolysis? In other terms, when can it occur?

This can only occur when the salt is molten or in solution so that the ions are separated and free to move.

What are cations?

These are positive ions

What are anions?

These are negative ions

Where do cations gain electrons from?

The cathode

Where do anions lose electrons?

In the anode

At which electrode does reduction occur?

At the cathode 

At which electrode does oxidation occur?

At the anode

What is the electrochemical series?

This is the order of reactivity with the most reactive at the top.

What happens as you go up the electrochemical series?

1. Reactivity increases

2. Electrons are lost more readily, so they form positive ions more readily.

What is preferential discharge?

This is when one type of cation and one type of anion are discharged in preference to any others present. 

What are the factors affecting the preferential discharge of anions?

1. The type of anode

2. The concentration of the electrolyte

3. The position of the ion in the electrochemical series.

What is the factor affecting the preferencial discharge of cations?

The position of the cation in the electrochemical series