Unit 10, 11, 12 & 13 - Electrolytic Processes/ Obtaining And Using Metals/ Transition Metals/ Alloys And Corrosion Flashcards
(97 cards)
What can acidified water be broken down into by electrolysis?
Hydro peen and oxygen
What is electrolysis?
Using an electrical current to break down substances
What is an electrolyte?
An ionic substance with freely moving ions and can conduct electricity
What happens to the electrolytes during electrolysis?
They move to the opposite charged electrode
What are the electrodes and which is which charge?
Anode: positive
Cathode: negative
What electrolytes move to which electrode?
Cation —> cathode
Anion —> anode
What is the acronym for electrodes
PANIC
What happens at each electrode?
Negative ions lose electrons, positive ions gain electrons
What is the acronym for oxidation and reduction?
OIL RIG
What is oxidisation? (Electrons)
Losing electrons
What is reduction (electrons)
Gaining electrons
Why are there chemical changes at the electrodes?
They change from charged ions to atoms or molecules
What do half equations show? (Electrolysis)
What happens at each electrode
What happens during electrolysis of copper sulphate solution when using a pure copper electrode and an impure copper electrode?
The copper at the impure electrode loses 2 electrons each, the copper ions them dissolve in the solution and move to the negative electrode and become pure copper. The impurities from the other electrode gathers at the bottom. The mass of the impure electrode decreases and the other increases
Explain the core practical - electrolysis of copper sulphate solution
Label a piece of copper the anode and another cathode. Measure the masses. Set up an electrolysis circuit and turn on power to 0.2 A. Leave for 20 minutes. Turn off power, wash in distilled, dip in propane and let the propane evaporate. Measure the masses of the electrodes. Repeat for different currents.
What type of electrodes do molten or dissolved ionic salts use?
Inert (unreactive) electrodes
When a molten salt is electrolysed, how are the ions discharged as?
Atoms or molecules
During electrolysis, what will the salt always decompose into?
It’s elements
Which elements of a salt are produced at which electrode?
Metal at cathode
Non metal at anode
When a solution is dissolved in water, what is important to remember about the ions?
There will be the dissolved ions as well as H+ and OH- ions
Electrolysis: copper chloride in aqueous solution, if the copper chloride decomposes but the water doesn’t change, what is the overall equation?
CuCl2(aq) —> Cu(s) + Cl2(g)
Electrolysis: sodium chloride aqueous solution, sodium chloride decomposes to form hydrogen and chlorine, sodium and hydroxide ions remain in solution, what is overall equation?
2NaCl(aq) + 2H2O(l) —> H2(g) + Cl2(g) + 2NaOH(aq)
What is the rule for the products formed at the cathode?
Least reactive ion
What is the rules for the product formed at the anode?
Halides (chlorine, bromine, iodine) > hydroxide > other ions