C6.1 - Introduction to electrolysis Flashcards
Electrolysis
Electrolysis is the breakdown of a substance containing ions by electricity
Electrolyte
Electrolyte is a: 1. Liquid Or, 2. Solution ,containing free-moving ions, which is broken down by electricity in the process of electrolysis
How is the electrical circuit for electrolysis set up?
The electrical circuit for electrolysis is set up with 2 electrodes that dip into the electrolyte, with a gap between them
The electrical circuit for electrolysis is set up with 2 electrodes that dip into the electrolyte, with a gap between them.
The electrodes are conducting rods.
What is one of the electrodes connected to?
One of the electrodes is connected to the positive terminal of a power supply
The electrical circuit for electrolysis is set up with 2 electrodes that dip into the electrolyte, with a gap between them.
The electrodes are conducting rods.
One of the electrodes is connected to the positive terminal of a power supply - this positive electrode is called the anode.
What is the other electrode connected to?
The other electrode is connected to the negative terminal of the power supply
Positively charged electrode
The positively charged electrode is the anode
Negatively charged electrode
The negatively charged electrode is the cathode
What are the electrodes often made of?
The electrodes are often made of:
1. An unreactive or inert substance, such as graphite
Or,
2. Sometimes expensive platinum metal
Examples of unreactive or inert substances that the electrodes are often made of
Examples of unreactive or inert substances that the electrodes are often made of are:
Graphite or sometimes expensive platinum metal
Inert
Inert is unreactive
Why are the electrodes often made of an unreactive or inert substance, such as graphite or sometimes expensive platinum metal?
The electrodes are often made of an unreactive or inert substance, such as graphite or sometimes expensive platinum metal
This is so the electrodes do not react with the electrolyte or the products made in electrolysis
During electrolysis, where do positively charged ions move to?
During electrolysis, positively charged ions move to the cathode (negative electrode)
During electrolysis, at the same time as positively charged ions moving to the cathode, where do negatively charged ions move to?
During electrolysis, at the same time as positively charged ions moving to the cathode, negatively charged ions move to the anode (positive electrode)
Why do positively charged ions move to the cathode (the negative electrode) and negatively charged ions move to the anode (the positive electrode) at the same time, during electrolysis?
Positively charged ions move to the cathode (the negative electrode) and negatively charged ions move to the anode (the positive electrode) at the same time, during electrolysis, because opposite charges attract
What happens when the ions reach the electrodes and they lose or gain electrons?
When the ions reach the electrodes and they lose or gain electrons, they:
- Lose their charge
- Become elements
What may happen at the electrodes?
At the electrodes:
1. Gases may be given off
Or,
2. Metals deposited
What does gases given off or metal deposited at the electrodes depend on?
Gases given off or metal deposited at the electrodes depend on:
- The compound used
- Whether it is molten or dissolved in water
Who was the 1st person to explain electrolysis?
The 1st person to explain electrolysis was Michael Faraday
What did Michael Faraday work on, nearly 200 years ago?
Nearly 200 years ago, Michael Faraday worked on:
- Electrolysis
- Many other problems in science
Why do ionic compounds not conduct electricity when they are solid?
Ionic compounds do not conduct electricity when they are solid, because their ions are in fixed positions in their giant lattice
What happens once an ionic compound is melted?
Once an ionic compound is melted, the ions:
- Are free to move around within the hot liquid
- Carry their charge towards the electrodes
Why does it take a lot of energy to melt many ionic substances and free the ions to move to electrodes in electrolysis?
It takes a lot of energy to:
1. Melt many ionic substances
2. Free the ions to move to electrodes in electrolysis
,because they have very high melting points
What do some ionic compounds do?
Some ionic compounds dissolve in water
In electrolysis, what are deposited from their aqueous solutions?
In electrolysis, only metals of very low reactivity, below hydrogen in the reactivity series, are deposited from their aqueous solutions
How can covalent compounds be electrolysed?
Covalent compounds cannot usually be electrolysed, unless they: 1. React Or, 2. Ionise in water to form ions
An example of a covalent compound reacting, or ionising in water to form ions
An example of a covalent compound reacting, or ionising in water to form ions is that acids in water always contain H+ (aq) ions plus negatively charged aqueous ions
What can you do, if you dissolve copper bromide in water?
If you dissolve copper bromide in water, you can decompose it by electrolysis
If you dissolve copper bromide in water, you can decompose it by electrolysis.
Copper metal, Cu (s), is what?
Copper metal, Cu (s), is formed at the cathode
Electrolyte is a liquid or solution, containing free-moving ions, which is broken down by electricity in the process of electrolysis.
Electrolysis is a what ionic compound?
Electrolyte is a: 1. Molten Or, 2. Dissolved ionic compound
Electrolyte is a liquid or solution, containing free-moving ions, which is broken down by electricity in the process of electrolysis.
Electrolyte is a molten, or dissolved ionic compound.
Electrolyte can conduct what?
Electrolyte can conduct electricity
The electrical circuit for electrolysis is set up with 2 electrodes that dip into the electrolyte, with a gap between them.
The electrodes are what?
The electrodes are conducting rods
The electrical circuit for electrolysis is set up with 2 electrodes that dip into the electrolyte, with a gap between them.
The electrodes are conducting rods.
One of the electrodes is connected to the positive terminal of a power supply.
This positive electrode is called the what?
This positive electrode is called the anode
The electrical circuit for electrolysis is set up with 2 electrodes that dip into the electrolyte, with a gap between them.
The electrodes are conducting rods.
One of the electrodes is connected to the positive terminal of a power supply - this positive electrode is called the anode.
The other electrode is connected to the negative terminal of the power supply.
This negative electrode is called what?
This negative electrode is called the cathode
The electrodes are often made of an unreactive or inert substance, such as what, or, sometimes expensive platinum metal?
The electrodes are often made of:
1. An unreactive or inert substance, such as graphite
Or,
2. Sometimes expensive platinum metal
When the ions reach the electrodes and they lose or gain electrons, they lose their charge and become elements.
They form what?
They form the uncharged element
When the ions reach the electrodes and they lose or gain electrons, they lose their charge and become elements.
They form the uncharged element and are what?
They:
- Form the uncharged element
- Are discharged from the electrolyte
Some ionic compounds dissolve in water and when this happens, the ions also become what?
Some ionic compounds dissolve in water and when this happens, the ions also become free to move around
If you dissolve copper bromide in water, you can decompose it by electrolysis.
Copper metal, Cu (s), is formed at the cathode.
Brown bromine, Br2 (aq), does what?
Brown bromine, Br2 (aq), appears in solution around the anode
