How to I get my head around Electrolysis?

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violetvictorious
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I can't seem to get my head around Electrolysis :mad:
I do understand it but there's so much to remember so I never get the elctrolysis marks in past paper questions
Help?
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Chlorophile
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(Original post by violetvictorious)
I can't seem to get my head around Electrolysis :mad:
I do understand it but there's so much to remember so I never get the elctrolysis marks in past paper questions
Help?
What specifically do you not understand? A lot of people struggle with it at GCSE but it'd help if you could say what exactly you find hard.
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username1332145
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Here is electrolysis in a nutshell:

Electrolysis means 'breaking down by electricity'. It is the process in which you supply an electric current through two electrodes-these are just two carbon 'rods' (made of graphite specifically as it has a high melting and boiling point and doesn't react as much as other substances do. However, the positive electrode reacts with oxygen molecules formed to form CO2 in some electrolysis reactions, so has to be replaced from time to time). Electrolysis only works on ionic substances! This is because the two electrodes have opposite charges, and ionic substances are the only substances to have positive and negative ions, unlike covalent substances. Furthermore, electrolysis only works when the ionic substances are either molten (melted) or dissolved in solution. It's crucial you remember this as it is because when they are solid, their ions are only able to vibrate about a fixed point; they cannot move. However, when molten or in solution- the ions are free to move. This means, that when electrolysis takes place, the ionic compound will be broken down into its positive and negative ions. The positive ions are attracted to the negative electrode (called the cathode) and the negative ions are attracted to the positive electrode (caled the anode) electrolysis is a highly useful process as it allows us to do many things. Aluminium for example is a highly useful metal, however is so reactive that we only find it in its ore: aluminium oxide. This is because it reacts as soon as it's exposed to the oxygen in our air. Aluminiums main ore is called bauxite. However, bauxite has a very high melting and boiling point so electrolysis would be very expensive as a lot of energy would be needed to melt bauxite. As a result, we dissolve aluminium oxide in another molten ore of aluminium called cryolite. This MASSIVELY reduces the boiling point and makes extraction of aluminium a much cheaper process.

Another thing you should know about it a process called electroplating. This is when we coat a cheaper metal, take brass, with a much more expensive metal, take gold this is how you get things like gold coated watches for example. In electroplating, we make the thing we want to plate our negative electrode (take a brass watch). Then we make the substance in which we want to coat the object our positive electrode (take, gold). We also make sure the electrolyte (molten solution in the electrolysis cell) contains ions of the plating metal- here gold. At the negative electrode (brass watch) metal ions (gold ions) gain electrons to form the metal ATOMS which are deposited on the object (gold ions gain electrons and form gold atoms, which deposited onto the watch plate/ coat it)


I hope this post was useful as it took me a while to write, if you need anything PM me at anytime!
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violetvictorious
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(Original post by Chlorophile)
What specifically do you not understand? A lot of people struggle with it at GCSE but it'd help if you could say what exactly you find hard.
I don't understand how you decide whether the substance moves to the negative electrode or the positive electrode and how many electrons the substance gains...

I know positively charged ions move to the negative electrode and negatively charged ions move to the positive electrode but how do you tell whether the ion is positive or negative in the first place?
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Hirondelle127
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(Original post by easyaspirsquared)
Here is electrolysis in a nutshell:

Electrolysis means 'breaking down by electricity'. It is the process in which you supply an electric current through two electrodes-these are just two carbon 'rods' (made of graphite specifically as it has a high melting and boiling point and doesn't react as much as other substances do. However, the positive electrode reacts with oxygen molecules formed to form CO2 in some electrolysis reactions, so has to be replaced from time to time). Electrolysis only works on ionic substances! This is because the two electrodes have opposite charges, and ionic substances are the only substances to have positive and negative ions, unlike covalent substances. Furthermore, electrolysis only works when the ionic substances are either molten (melted) or dissolved in solution. It's crucial you remember this as it is because when they are solid, their ions are only able to vibrate about a fixed point; they cannot move. However, when molten or in solution- the ions are free to move. This means, that when electrolysis takes place, the ionic compound will be broken down into its positive and negative ions. The positive ions are attracted to the negative electrode (called the cathode) and the negative ions are attracted to the positive electrode (caled the anode) electrolysis is a highly useful process as it allows us to do many things. Aluminium for example is a highly useful metal, however is so reactive that we only find it in its ore: aluminium oxide. This is because it reacts as soon as it's exposed to the oxygen in our air. Aluminiums main ore is called bauxite. However, bauxite has a very high melting and boiling point so electrolysis would be very expensive as a lot of energy would be needed to melt bauxite. As a result, we dissolve aluminium oxide in another molten ore of aluminium called cryolite. This MASSIVELY reduces the boiling point and makes extraction of aluminium a much cheaper process.

Another thing you should know about it a process called electroplating. This is when we coat a cheaper metal, take brass, with a much more expensive metal, take gold this is how you get things like gold coated watches for example. In electroplating, we make the thing we want to plate our negative electrode (take a brass watch). Then we make the substance in which we want to coat the object our positive electrode (take, gold). We also make sure the electrolyte (molten solution in the electrolysis cell) contains ions of the plating metal- here gold. At the negative electrode (brass watch) metal ions (gold ions) gain electrons to form the metal ATOMS which are deposited on the object (gold ions gain electrons and form gold atoms, which deposited onto the watch plate/ coat it)


I hope this post was useful as it took me a while to write, if you need anything PM me at anytime!
Just wanted to say - you are the most amazing person in the world right now. I didn't understand electrolysis either and you are a life saver!!!!! Ghaaa - random person on the internet - you are amazing. Thank you so so much.
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violetvictorious
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(Original post by easyaspirsquared)
Here is electrolysis in a nutshell:

Electrolysis means 'breaking down by electricity'. It is the process in which you supply an electric current through two electrodes-these are just two carbon 'rods' (made of graphite specifically as it has a high melting and boiling point and doesn't react as much as other substances do. However, the positive electrode reacts with oxygen molecules formed to form CO2 in some electrolysis reactions, so has to be replaced from time to time). Electrolysis only works on ionic substances! This is because the two electrodes have opposite charges, and ionic substances are the only substances to have positive and negative ions, unlike covalent substances. Furthermore, electrolysis only works when the ionic substances are either molten (melted) or dissolved in solution. It's crucial you remember this as it is because when they are solid, their ions are only able to vibrate about a fixed point; they cannot move. However, when molten or in solution- the ions are free to move. This means, that when electrolysis takes place, the ionic compound will be broken down into its positive and negative ions. The positive ions are attracted to the negative electrode (called the cathode) and the negative ions are attracted to the positive electrode (caled the anode) electrolysis is a highly useful process as it allows us to do many things. Aluminium for example is a highly useful metal, however is so reactive that we only find it in its ore: aluminium oxide. This is because it reacts as soon as it's exposed to the oxygen in our air. Aluminiums main ore is called bauxite. However, bauxite has a very high melting and boiling point so electrolysis would be very expensive as a lot of energy would be needed to melt bauxite. As a result, we dissolve aluminium oxide in another molten ore of aluminium called cryolite. This MASSIVELY reduces the boiling point and makes extraction of aluminium a much cheaper process.

Another thing you should know about it a process called electroplating. This is when we coat a cheaper metal, take brass, with a much more expensive metal, take gold this is how you get things like gold coated watches for example. In electroplating, we make the thing we want to plate our negative electrode (take a brass watch). Then we make the substance in which we want to coat the object our positive electrode (take, gold). We also make sure the electrolyte (molten solution in the electrolysis cell) contains ions of the plating metal- here gold. At the negative electrode (brass watch) metal ions (gold ions) gain electrons to form the metal ATOMS which are deposited on the object (gold ions gain electrons and form gold atoms, which deposited onto the watch plate/ coat it)


I hope this post was useful as it took me a while to write, if you need anything PM me at anytime!
Thank you for taking your time to help me Are you doing A levels atm? If so, what did you get in your chemistry GCSE if you don't mind me asking? You sound like you know your stuff
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studos
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I think you should consider electrolysis as an effective hair removal method
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Chlorophile
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(Original post by violetvictorious)
I don't understand how you decide whether the substance moves to the negative electrode or the positive electrode and how many electrons the substance gains...

I know positively charged ions move to the negative electrode and negatively charged ions move to the positive electrode but how do you tell whether the ion is positive or negative in the first place?
Firstly, consider why substances are positively or negatively charged in the first place. Remember that electrons are negatively charged and protons are positively charged. If something is positively charged, it has an electron deficiency. If something is negatively charged, it has an electron surplus. When we have ions in solution or molten, the negative ions (with an electron surplus) will move towards the positive electrode (with an electron deficiency) to get rid of their surplus electrons. Conversely, the positive ions (with an electron deficiency) will move towards the negative electrodes (with an electron surplus) to gain their lost electrons. The number of electrons they lose or gain depends on the ion.

Say we have Na+ and Cl- ions in solution. The sodium ions have a charge of +1, so they need to gain one electron to become an atom again. Therefore, the sodium ions go towards the negative electrode (with the electron surplus) in order to gain their lost electrons again. On the other hand the chlorine ions have a charge of -1 so they have one electron to many. They move towards the positive electrode and lose an electron to become an atom with no charge again.

You can tell whether or not an ion is positively charged or negatively charged by understanding their electron arrangement. As a rule of thumb, all elements in Groups 1-3 and the transition metals form positive ions because it's easier for them to lose electrons to get a full outer shell than gain electrons. All elements in Groups 5-8 form negative ions because it's easier for them to gain electrons to get a full outer shell than lose electrons.

Does that make sense?


(Original post by easyaspirsquared)
Here is electrolysis in a nutshell:

Electrolysis means 'breaking down by electricity'. It is the process in which you supply an electric current through two electrodes-these are just two carbon 'rods' (made of graphite specifically as it has a high melting and boiling point and doesn't react as much as other substances do. However, the positive electrode reacts with oxygen molecules formed to form CO2 in some electrolysis reactions, so has to be replaced from time to time). Electrolysis only works on ionic substances! This is because the two electrodes have opposite charges, and ionic substances are the only substances to have positive and negative ions, unlike covalent substances. Furthermore, electrolysis only works when the ionic substances are either molten (melted) or dissolved in solution. It's crucial you remember this as it is because when they are solid, their ions are only able to vibrate about a fixed point; they cannot move. However, when molten or in solution- the ions are free to move. This means, that when electrolysis takes place, the ionic compound will be broken down into its positive and negative ions. The positive ions are attracted to the negative electrode (called the cathode) and the negative ions are attracted to the positive electrode (caled the anode) electrolysis is a highly useful process as it allows us to do many things. Aluminium for example is a highly useful metal, however is so reactive that we only find it in its ore: aluminium oxide. This is because it reacts as soon as it's exposed to the oxygen in our air. Aluminiums main ore is called bauxite. However, bauxite has a very high melting and boiling point so electrolysis would be very expensive as a lot of energy would be needed to melt bauxite. As a result, we dissolve aluminium oxide in another molten ore of aluminium called cryolite. This MASSIVELY reduces the boiling point and makes extraction of aluminium a much cheaper process.

Another thing you should know about it a process called electroplating. This is when we coat a cheaper metal, take brass, with a much more expensive metal, take gold this is how you get things like gold coated watches for example. In electroplating, we make the thing we want to plate our negative electrode (take a brass watch). Then we make the substance in which we want to coat the object our positive electrode (take, gold). We also make sure the electrolyte (molten solution in the electrolysis cell) contains ions of the plating metal- here gold. At the negative electrode (brass watch) metal ions (gold ions) gain electrons to form the metal ATOMS which are deposited on the object (gold ions gain electrons and form gold atoms, which deposited onto the watch plate/ coat it)


I hope this post was useful as it took me a while to write, if you need anything PM me at anytime!
This is brilliantly explained, by the way.
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violetvictorious
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(Original post by Chlorophile)
Firstly, consider why substances are positively or negatively charged in the first place. Remember that electrons are negatively charged and protons are positively charged. If something is positively charged, it has an electron deficiency. If something is negatively charged, it has an electron surplus. When we have ions in solution or molten, the negative ions (with an electron surplus) will move towards the positive electrode (with an electron deficiency) to get rid of their surplus electrons. Conversely, the positive ions (with an electron deficiency) will move towards the negative electrodes (with an electron surplus) to gain their lost electrons. The number of electrons they lose or gain depends on the ion.

Say we have Na+ and Cl- ions in solution. The sodium ions have a charge of +1, so they need to gain one electron to become an atom again. Therefore, the sodium ions go towards the negative electrode (with the electron surplus) in order to gain their lost electrons again. On the other hand the chlorine ions have a charge of -1 so they have one electron to many. They move towards the positive electrode and lose an electron to become an atom with no charge again.

You can tell whether or not an ion is positively charged or negatively charged by understanding their electron arrangement. As a rule of thumb, all elements in Groups 1-3 and the transition metals form positive ions because it's easier for them to lose electrons to get a full outer shell than gain electrons. All elements in Groups 5-8 form negative ions because it's easier for them to gain electrons to get a full outer shell than lose electrons.

Does that make sense?




This is brilliantly explained, by the way.
Thank you, God bless



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username1332145
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(Original post by Hirondelle127)
Just wanted to say - you are the most amazing person in the world right now. I didn't understand electrolysis either and you are a life saver!!!!! Ghaaa - random person on the internet - you are amazing. Thank you so so much.
Haha thank you that's made my day! If you have any more questions you can PM me!
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username1332145
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(Original post by violetvictorious)
Thank you for taking your time to help me Are you doing A levels atm? If so, what did you get in your chemistry GCSE if you don't mind me asking? You sound like you know your stuff
No I'm in year 11 at the moment, just done my chemistry revision and have a great teacher! I got an A* in my mock so hopefully will get that in the real thing :P glad I could help
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username1332145
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This is brilliantly explained, by the way.[/QUOTE]

Thank you! Means a lot as I have seen some of you chemistry posts and you sound great at it!
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