Transition Metals and Reactions of Ions in Aqueous Solution Flashcards
When anhydrous aluminium chloride reacts with water, solution Y is formed that contains a complex aluminium ion, Z, and chloride ions. Give an equation for this reaction. Give an equation to show how the complex ion Z can act as a Brønsted–Lowry acid with water. Describe two observations you would make when an excess of sodium carbonate solution is added to solution Y. Give an equation for the reaction. In your equation, include the formula of each complex aluminium species. Aqueous potassium hydroxide is added, until in excess, to solution Y. Describe two observations you would make. For each observation give an equation for the reaction that occurs.
In your equations, include the formula of each complex aluminium species
- AlCl3 + 6H2O -> [Al(H2O)6]^3+ + 3Cl-
- [Al(H2O)6]^3+ + H2O -> [Al(H2O)5(OH)]^2+ + H3O+
- White ppt/solid
- Effervescence/bubbles/fizzing
- 2[Al(H2O)6]^3+ + 3CO3^2– -> 2[Al(H2O)3(OH)3] + 3CO2 + 3H2O
- White ppt/solid
- [Al(H2O)6]^3+ +3OH– -> [Al(H2O)3(OH)3] + 3H2O
- Colourless solution forms / ppt or solid dissolves
- [Al(H2O)3(OH)3] + OH- -> [Al(H2O)2(OH)4]– + H2O
OR
[Al(H2O)3(OH)3] + OH- -> [Al(OH)4]– + 3H2O
Which transition metal ion complexes are strong enough to act as Brønsted–Lowry acids with carbonates?
3+ complexes ONLY. 2+ aren’t strong enough
Vanadium(V) oxide is the catalyst used in the manufacture of sulfur trioxide. Give two equations to show how the catalyst is used and regenerated
V2O5 + SO2 -> V2O4 + SO3
V2O4 + ½O2 -> V2O5
Explain the acid-base properties of metal aqua ions
When these ions are in solution, they’re acidic. Metal ions that form 2+ ions, iron(II) and copper(II), form weaker acidic solution than those that form 3+ ions, iron(III) and aluminium. Therefore the 3+ ions dissociate more and have a greater attractive power to OH-, basic ions, i.e. they’re stronger acids
What type of reaction is it between metal aqua ions and NaOH?
Neutralisation
Give the equation and colour change when hexaaqua iron(II) reacts with NaOH
[Fe(H2O)6]^2+ + 2OH- -> [Fe(H2O)4(OH)2] + 2H2O
Colour change: Green solution to green precipitate
Which metal aqua ion reacts with NaOH to have a colour change from green solution to green precipitate?
Hexaaqua Iron(II)
Give the equation and colour change when hexaaqua copper reacts with NaOH
[Cu(H2O)6]^2+ + 2OH- -> [Cu(H2O)4(OH)2] + 2H2O
Colour change: Blue solution to blue precipitate
Which metal aqua ion reacts with NaOH to have a colour change from blue solution to blue precipitate?
Hexaaqua Copper
Give the equation and colour change when hexaaqua iron(III) reacts with NaOH
[Fe(H2O)6]^3+ + 3OH- -> [Fe(H2O)3(OH)3] + 3H2O
Colour change: Purple solution to purple precipitate
What colour is hexaaqua copper?
Blue solution
What colour is hexaaqua cobalt?
Pink solution
What colour is hexaaqua iron(II)?
Green Solution
Discuss the role of iron as a heterogeneous catalyst in the Haber process.
3 H2 + N2 ⇌ 2 NH3
Your answer should include:
- the meaning of the term heterogeneous catalyst
- how iron acts as a heterogeneous catalyst
- the factors that affect the efficiency and lifetime of the catalyst
- Heterogeneous means in a different phase/state from reactants
- Catalyst speeds up reaction and is left unchanged OR lowers the activation energy for the reaction
- How iron acts as a heterogeneous catalyst:
- Hydrogen and nitrogen/reactants adsorb onto the surface/active sites of the iron
- Bonds weaken/reaction takes place
- Products desorb/leave from the surface (of the iron)
- Factors that affect the efficiency and lifetime of the catalyst
- Large surface area (of iron) by using powder or small pellets
or support medium/mesh - Catalyst poisoned / sulfur poisons or binds to the catalyst
- Active sites blocked
Ignore references to temperature and pressure
In the Contact process, sulfur(IV) oxide is converted into sulfur(VI) oxide using
vanadium(V) oxide as a catalyst. Give two equations to show how the vanadium(V) oxide acts as a catalyst in this process
- V2O5 + SO2 → V2O4 + SO3
- V2O4 + 0.5O2 → V2O5
