3.2.6 Reactions of ions in aqueous solution (A2) Flashcards
What is the formula when Iron (II) is an aqueous ion?
[Fe(H2O)6]2+ (aq)
what colour is Iron (II) as an aqueous ion?
green (green solution)
what ion is produced when we have Iron (II) and involve the action of NaOH (sodium hydroxide)?
Fe(H2O)4(OH)2 (s)
what happens when NaOH reacts with Iron (II)?
green precipitate goes brown on standing in air
what is the action of excess NaOH (aq) on Iron (II)?
No further change
What is the action of NH3 (aq) on Iron (II)?
green precipitate goes brown on standing in air
what is formed when NH3 reacts with Iron (II)?
Fe(H2O)4(OH)2 (s)
What is the action of excess NH3 (aq) on Iron (II)?
no further change
What do we see when Na2CO3 (aq) reacts with Iron (II)?
green precipitate
what is formed when Iron (II) reacts with Na2CO3 (aq)?
FeCO3
What is the formula of Copper (II) as an aqueous ion?
[Cu(H2O)6]2+ (aq)
Are 2+ ions or 3+ ions more acidic in solution? Why?
3+ ions are much more acidic
they are smaller and more highly charged, so have a higher charge density.
They attract the electrons from the oxygen of the ligands much more strongly.
This weakens the O-H bonds, so the complex readily releases H+ ion into the solution, making it acidic.
Write an equation for the hydrolysis of a 3+ ion to release a proton.
[Fe(H2O)6]3+(aq) <—> [Fe(H2O)5(OH)]2+(aq) + H+(aq)
Why does the green ppt go brown on standing in air in the reaction with Fe2+ with NH3?
Oxygen in the air oxidises Fe2+ and Fe3+ and [Fe(OH)3(H2O)3] is brown, so colour changes
What complex ion is formed from Fe2+ in aqueous solution? what colour is seen?
[Fe(H2O)6]2+ (aq)
green
what colour is [Fe(H2O)6]2+ (Fe2+ in aqueous solution)?
Green
What complex is formed from Fe2+ and NaOH (sodium hydroxide)? what colour is seen?
[Fe(H2O)4(NH)2] (s)
green ppt, goes brown on standing in air
What colour is [Fe(H2O)4(NH)2] (s) (Fe2+ in NaOH)
green ppt, goes brown on standing in air
What complex is formed when NH3 is added to Fe2+? what colour is seen?
[Fe(H2O)4(OH)2] (s)
green ppt, goes brown on standing in air
What colour is [Fe(H2O)4(OH)2] (s) (Fe2+ in NH3)
green ppt, goes brown on standing in air
What is formed when Fe2+ is added to Na2CO3? what colour is seen?
FeCO3
green ppt
What colour is FeCO3?
green ppt
What complex ion is formed from Cu2+ in aqueous solution? what colour is seen?
[Cu(H2O)6]2+
blue
What colour is [Cu(H2O)6]2+ (Cu2+ in aqueous solution)?
blue