ELECTROLYSIS

Question 1

SOLUBLE vs INSOLUBLE in practical

Answer 1

SOLUBLE - eg. CuSo4

! Dissolve in water to get aqueous solution

INSOLUBLE - PbBr2

! Must MELT to get MOLTEN liquid - IONS free to move

Question 2

ELECTROLYSIS

Answer 2

Using electricity to convert IONS in a compound back into thier PURE ELEMENTAL form

Question 3

METAL EXTRACTION for metals LESS reactive than C

Answer 3

OXIDES ——> REACTIVE METALS

! Via REDUCTION w CARBON

Eg. 2CuO+ C ——-reduction —> 2Cu + CO2 ! 2Cu = PURE

:( only can be displaced y C if is < reactive

Question 4

METAL EXTRACTION w metals MORE reactive than C

Answer 4

! Via ELECTROLYSIS
—-> Expensive $$$ more ENERGY - HIGH TEMP

Note : metal must be MOLTEN

1) PURIFY metal OXIDE

2) mix metal with CRYOLITE - to lower melting point

3) MELT to form MOLTEN mixture

! Oxygen gas should be released and PURE metal will form

Question 5

ELECTROLYSIS - AQUEOUS SOLUTIONS

Answer 5

Soluble - dissolved in water ot form AQ solution

! WATER splits up

H2O (l) —> H (aq) + OH- (aq)

Question 6

Negative CATHODE

Answer 6

-VE CAThode - attracts METAL and H+

! Only ONE - less REACTIVE ION - will discharge

Eg. Cu & H+. Cu will dicharge

     Na & H+            H+ will discharge

Question 7

POSITIVE ANONDE

Answer 7

+ve ANODE attracts -ve ION and OH- IONS

! Only ONE will be discharged

HALIDE present? - HALIDE is discharged

HALIDE NOT present ? - OH- is discharged. ALWAYS.

Question 8

CuSO4

Answer 8

Cu 2+ &. SO4 ^2- As well as. H+ & OH -

CATHODE - discharges Cu - acculmalates around as a solid

ANONDE - discharges OH

4OH- ——> 2H2O + O2 + 4e-