C6 Electrolysis Flashcards
why cannot solid ionic compounds cannot conduct electricity .
The ions are locked in place and are not free to move , they are held together by strong electrostatic forces of attraction .
Why can ionic compounds that are molten or dissolved in water conduct electricity ?
the forces of attraction are broken and the ions are free to move .
what are electrolytes
compound that is broken down by electrolysis and therefore can conduc electricity
what are the two ions n lead bromine
Pb2+ Br-
how many electrodes are in electrolysis
two
what are the electrodes made of
conducting materal such as graphite or a metal .
what is the negative electode
cathode
what is the positive electrode
anode
what happens pb2+ (lead) whta type of reaction is ths
the Pb+ gain two electrons from Pb atoms this is called Reduction
Pb—>pb2+ +2e-
what happens in reduction
u gain electrons
What happens to Br-
Br- looses oe electron to for Br atoms this is called oxidation
what happens in oxidiation
loose electrons
what is electrolysis
electrolysis is the breakdown of a substance conataining ions by electricity
how are metals less reactive than carbon extracted
metals less reactive than carbon cna be extracted by reduction with carbon .
how are metals more reactive than carbon extracted.
Metals more reactive than carbon can be extracted using electrolysis .
What does aluminium oxide contain
it contains aluminum ions (AL3+) and Oxide ions (02-)
why is aluminium oxide not produced by the electrolysis of an aqueous solution ?
As aluminium oxide is insoluble in water .
what is the first step of electrolysis with aluminium oxide
aluminium oxide is mixed with cryolite .
why is aluminium oxide mixed with cryolite
as it lowers the melting point of aluminium oxide as it as a high a very high melting point , reducing the amount of energy needed and saves money for electrolysis .
what are the anode and cathode made of and why ?
Made of graphite , as it is a very good conductor of electricity and has a very high melting point .
where are the AL3+ ions attracted to.
AL3+ ions are attracted to the cathode (the negative electrode .
Give the half equation at the cathode for aluminium oxide what type of reaction is it and why
AL3+ + 3E- arrow AL - it is a reduction as each ion gains three electrons and forms aluminium atoms .
Why is aluminium ions attracted to the negative elctorde
As aluminium ions are metals so are positively charged so are atracted to the negative electrode as opposites attract and gain three electrons ,
where are oxide ions attracted to in alumnium oxide
02- ions are attracted to the anode (positive terminal)
what is the half equation at the anode for aluminium oxide . What type or reaction is it and why
202-4e-arrowO2 it is oxidation as the oxide ions loses two electrons to form an oxygen atom .
Why must the anode be replaced regularly
wrtie the equation for this .
as the oxygen molecules produced at the anode react with the graphite (carbon) , forming C02 gas .
c+02arrow co2
why do u need to double everything at the anode for aluminium oxide
as oxygen atoms at the anode pair up up to form oxygen molecules .
give two reasons why electrolysis is expensive
- Melting the compounds such as aluminium oxide requires a great deal of energy .
- A lot of energy is required to produce the electric current .
Meaning of aqueous solutions
dissolved in water
water molecules ionise (split) forming what ?
hydrogen ions H+
and hyrdoxide ions OH-
what is the formula for Copper sulfate solution
CuSO4(aq)
what does CuSO4 split into
CU2+
SO42-
and H+ -hydrogen ions and OH- hydroxide ions because aqueous
What are the two possible things that can be produced at the cathode for copper sulfate solution .
Cu2+
or H+
which one is porduced at the cathode at copper sulfate solution and why .
Hydrogen is produced at the cathode if the metal is more reactive than hydrogen .
Copper is less reactive than hydrogen os i produced
What is produced at the anode for copper sulfate solution
oxygen gas , usually , when carrying out electrolysis on an aqueous solution , we usually get oxygen produced at the anode .
Why should electrodes be inert
As it is important that electrodes do notg react witht he chemicals that were making an electrolysis .
what is the meaning of inert
do not react .
what material is often used as inert electrodes and why
platinum is ofen used as inert electrodes as platinum is a very unreactive material .
What is the half equation at the cathode for copper sulfate solution
Cu2+ +2e- —> Cu
what type of reaction is at the cathode for copper sulfate solution and why
it is a reduction as copper ions gain 2 electrons to become copper attoms .
what is the half equation for the anode for copper sulfate solution and why . What type of reaction is it ?
40H—-> 02+ 2H20 + 4e-
hydroxide ions react to make oxygen and water and use 4 electrons in the process so it is an OXIDATION REACTION .
What is the formula for sodium chloride
NaCl
what two ions is sodium chloride made up of
Na+ sodium ions
and
Cl- and chloride ions
and H+-hrdogen ions and OH- hydroxide ions as it is in an aqueous solution .
What are the two potential discharges at the cathode for sodium chloride
Na+ sodium ions
H+ hydrogen ions
What is produced at the cathode for sodium chloride
Hydrogen is prooduced at the cathode if the metal is more reactive than hydrogen . Sodium is MORE reactive than hydrogen so HYDROGEN is produced at the CATHODE
What are the two potential discharges at the anode for sodium chloride
Cl- chlorine ions
OH- hydroxide ions
what is produced at the anode for sodium chloride
If the aqueous solution contains halide ions (Cl-,Br-,I-) then the halogen will be produced at the anode otherwise oxyegn .As the sodium chloride contains chloride ions , CHLORINE GAS will be produced at the ANODE .
What is thehalf equation and reaction at the cathode for sodium chloride
2H+ + 2e —> H2
The hydrogen ion is gaining one electron to become a hyrdogen atom so is a REDUCTION . However hydrogen atoms pair to make hydrogen molecules so everything doubles .
What is the half equation and reaction at the anode for sodium chloride
2CL- —>cL2 +2e-
The chloride ion looses one electron to form a chloride atom so it is an OXIDATION , however , chlorine atoms pair to form chlorine molecules so everything doubles .
what is a positively charged ion called
cation
what is a negatively charged ion called
anion
