Hello! I am also doing the C2 and C3 exams tomorrow, so nervous!
-Electrolysis is passing an electrical current through a molten ionic compound in order to break down a substance. The substance which is broken down is the electrolyte.
-Two electrodes make contact with the electrolyte- the positive and negative electrodes
-The ions move to the electrode where they are discharged to produce elements- so the negatively charged ions are attracted to the positive electrode and the positively charged ions are attracted to the negative electrode
-At the positive electrode, where the negatively charged ions go, metals and hydrogen gas are formed.
-At the negative electrode, non-metallic elements are formed (the positively charged ions lose their charge and become non-metallic elements)
-Negative electrode- gain electrons- this is reduction as the positive ions have been reduced (electrons are negative so when electrons are gained they cause a positive ion to become neutrally charged)
-Positive electrode- lose electrons- this is oxidation. Negative ions lose electrons and become neutral.
If you need to know more about electrolysis feel free to message me but I feel that is the basis of the topic, however there are other elements to it such as the extraction of aluminium or electrolysis in brine. Let me know if you'd like me to go over those!
Acids + bases-
-Alkalis are bases. They dissolve in water to make alkaline solutions
-Alkalis produce hydroxide ions (OH-)
-When acids are added to water they produce hydrogen ions (H+)
-The ionic equation for neutralisation is H+ + OH- = H2O
-When metals react with acids they produce a salt and hydrogen
-Acid + metal = a salt + hydrogen
-When an acid reacts with a base a neutralisation reaction occurs and salt and water are produced
-Acid + base = a salt +water
-To product a salt= a metal or base that is insoluble in water is added a little at a time to the acid until the reaction is complete. It is then filtered to remove excess solid reactant which leaves a salt solution. The solid salt is made when the salt solution is evaporated, and then it crystallizes.
Message me if you need to know anything else but I've just summarised the essentials from the AQA chemistry revision guide pages 62-65