Electrolysis Flashcards
What is electrolysis?
Electrolysis is the process by which ionic substances are broken down into simpler substances using electricity. During electrolysis, metals and gases may form at the electrodes.
What must happen for electrolysis to work?
For electrolysis to work, the ions must be free to move. Ions are free to move when an ionic substance is dissolved in water or when melted.
What happens during electrolysis?
Positively charged ions move to the negative electrode during electrolysis. They receive electrons and are reduced.
Negatively charged ions move to the positive electrode during electrolysis. They lose electrons and are oxidised.
The substance that is broken down is called the electrolyte.
What is electrolysis used for?
Electroplate objects.
How does electroplating work?
The negative electrode should be the object that is to be electroplated
The positive electrode should be the metal that you want to coat the object with
The electrolyte should be a solution of the coating metal, such as its metal nitrate or sulphate.
What is aluminium and why is it expensive?
Aluminium is the most abundant (found in large quantities) metal on Earth. But it is expensive, largely because of the amount of electricity used up in the extraction process.
What is the aluminium ore called?
Bauxite.
What happens at the negative electrode?
At the negative electrode, positively charged ions gain electrons. This is reduction, and you say that the ions have been reduced.
What happens at the positive electrode?
At the positive electrode, negatively charged ions lose electrons. This is oxidation, and you say that the ions have been oxidised.
What happens when an electric current passes through a concentrated sodium chloride solution?
Hydrogen gas forms at the negative electrode and chlorine gas forms at the positive electrode. A solution of sodium hydroxide forms.
What are the three products of electrolysis?
Hydrogen is used as a fuel and for making ammonia.
Chlorine is used to kill bacteria in water, and to make bleach and plastics.
Sodium hydroxide is used to make soap and bleach.
How is a half-equation balanced?
By adding, or taking away, a number of electrons equal to the total number of charges on the ions in the equation.
