A2 Transition metal chemistry 2

1

Electrochemical cells

1

Electrochemical cells

Nearly everyone gets this question wrong the first time they try it - you have been warned!

1

Electrochemical cells

1

Conventional representation

This is a very picky question, take care!

9

Describe the reactions of separate samples of aqueous cobalt(II) sulfate with aqueous sodium hydroxide, 

 ammonia 

and concentrated hydrochloric acid. For each reaction, link your description to an appropriate equation. State symbols are not required. (6)
Sodium hydroxide 
 _________ solution to _________  ________________      
Reaction type = (deprotonation / precipitation / ______________ )
Equation
 [Co(H₂O)₆]²⁺ + 2OH⁻ → [Co(H₂O)₄(OH)₂] + 2H₂O
Excess aqueous ammonia 
Formation of) __________ /yellow/yellow-brown/brown _____________  
Reaction type ____________________ 

Concentrated hydrochloric acid
Formation of dark _________  solution ____________________ 
[Co(H₂O)₆]²⁺ + 4Cl⁻(aq) → [CoCl₄]₂⁻ + 6H₂O /

Electrochemical cells

Electrochemical cellsNearly everyone gets this question wrong the first time they try it - you have been warned!

Electrochemical cells

Conventional representationThis is a very picky question, take care!

Describe the reactions of separate samples of aqueous cobalt(II) sulfate with aqueous sodium hydroxide,

Sodium hydroxide

Excess aqueous ammonia

Concentrated hydrochloric acid

Electrochemical cells

Nearly everyone gets this question wrong the first time they try it - you have been warned!

Conventional representation

This is a very picky question, take care!