Electrolysis: Molten Flashcards
Explain why ionic compounds can conduct electricity when molten or dissolved in water. Describe the reactions taking place at the anode or cathode during electrolysis.
Why are solid ionic compounds unable to conduct electricity?
Solid ionic compounds are unable to conduct electricity as the IONS are not delocalised and therefore cannot carry a charge.
What happens to the strong electrostatic forces in ionic compounds when melted or dissolved in water?
What happens to the electrons?
The strong electrostatic forces are now broken when an ionic compound is molten and the ions are now free to move / delocalised.
Why must a solution be molten for electrolysis to take place?
A solution must be molten for electrolysis to take place as the ions must be delocaslised / free to move to the electrode.
DO NOT REFER TO ELECTRONS.
What is an electrolyte? (1)
An electrolyte is a liquid ionic compound after being melted.
What are the two electrodes in electrolysis made of?
The two electrodes in electrolysis are made of graphite or another metal which can conduct electricity.
What is the name of the negative electrode and what is it covered with?
The negative electrode is called the cathode and it’s covered with electrons.
What is the name of the positive electrode and what does it lack?
The positive electrode is called the anode and it does not have any electrons.
Where are the positive lead ions attracted to in the electrolysis of molten lead bromide and why? (Pb2+Br-)
The positive lead ions (Pb2+) are attracted to the cathode as the opposite charges attract.
Where are the negative bromide ions attracted to in the electrolysis of molten lead bromide and why? (Pb2+Br-)
The negative bromide ions (Br-) are attracted to the anode as apposite charges attract.
What happens to the positive lead ions (Pb2+) after they are attracted to the cathode? And what type of reaction is this an example of? Write a half equation showing this.
The positive lead ions (Pb2+) gain two electrons to form lead (Pb) atoms. Because the positive lead ions are gaining electrons this is an example of a reduction reaction.
What does it mean if somethings molten?
If somethings molten it means its melted.
What happens to the negative bromide ions (Br-) when they are attracted to the anode? And what type of reaction is this an example of? Write a half equation showing this.
The negative bromide ions (Br-) loose an electron to form Br atoms. Because the negative bromide ions loose an electron this is an example of an oxidation reaction.
(Further explanation: The ion Br- has eight electrons in its outer shell. The anode is positive and can take one of those electrons. This forms the atom Br which has seven electrons in its outer shell. Two Br atoms can form a a covalent bond, sharing a pair of outer electrons and becoming stable. So because it can lose one electron and form a stable covalent bond that is what happens to Br- during electrolysis.) Bromine atoms pair to form a molecule hence the two.
Why can’t solid ionic compounds conduct electricity?
Solid ionic compounds cannot conduct electricity this is because the ions are not free to move and therefore cannot carry a charge. (They are held together by strong electrostatic forces.)
