Electrolysis Flashcards
How do atoms form ions (NaCl)
-Sodium atom loses one electron to form a Na ion with a +1 charge
-The chlorine atom is in group 7 so it will gain one electron to form a chlorine ion with a -1 charge
-Oppositely charged ions are held by electrostatic forces of attraction this is a strong ionic bond
How are ionic bonds formed (CaCl)
-Ca atom loses 2 electrons to form a calcium with with a 2+ charge
-Two chlorine atoms both gain one electron forming 2 Cl- ions
-Formula would now be CaCl2
What is the point of all bonding
-Full Outer shell
What structure do ionic bonds form
-Giant ionic lattice
What properties do ionic bonds have
-High melting point due to lots of strong bonds so lots of energy needed to break
-Doesn’t conduct as a solid as the ions are held in the giant lattice - do not move
-Can conduct if they are molten/aqueous as the ions are mobile and they can carry charge
What does aq mean
aqueous - dissolved in water
What does electrolysis mean
-When an ionic compound is split into its elements
Electrolysis (Al2O3)
-Molten aluminium oxide
-Aluminium will lose 3 electrons so the charge is 3+
-Oxygen will gain two so the charge is 2-
-At the anode the oxygen will be attracted and is oxidised
-At the cathode the aluminium will be attracted and be reduced
Why is the molten salts put in cryolite
Lowers the melting point
What will a salt always contain
-A positive metal
-A negative non-metal
-Water always present (OH- and H+ ions) due to the aqueous quality
Ionic equation for neutralisation
H+ + OH -> H2O
Rule at anode for electrolysis of aqueous salts
-Negative ion is attracted and the simplest one is given off
Rule at cathode for electrolysis of aqueous salts
-Positive ions are attracted and the least reactive is given off
