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NOTE: The cathode (negative) attracts Pb2+ ions as they are positive, the anode (positive) attracts Br- ions as they are negative
- As soon as the lead(II) Bromide melts(becomes molten), the ions become free to move around, this movement enables the ions move allowing a charge to flow, meaning electrolysis can take place.
- The electrodes are made out of carbon - which is inert (unreactive).
- Connect the electrodes to a power source
- The positive lead (II) ions are attracted to the cathode, which is the negative electrode. When they get there, they gain 2 electrons each from the electrode. This forms lead atoms (they are no longer ions as they have no charge). These 'fall' to the bottom of the container as molten lead.
- Bromide ions (negative) are attracted to the positive anode. When they get there, the extra electron which makes the bromide ion negatively charged moves onto the anode, this loss of the extra electron turns each bromide ion into a bromine atom. These join in pairs (bond covalently) to form bromine molecules (which is gas).
The half equations...
At the cathode: Pb2+ + 2e- ----> Pb
At the anode: 2Br- ---> Br2 + 2e-
This is really helpful, but just wanted to point out that the electrons do not flow freely in molten or solute ionic substances, but it is the ions that move around (you got this, but then went on to say that the electrons move around). You could say that this allows the "charge" to flow around instead of electrons maybe.
ReplyDeleteMy mistake, thank you for pointing it out! All fixed now. I hope paper 1 went well for you, don't hesitate to comment if you have any queries or are unsure of anything :) X
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