15B: Reactions of transition metal elements
No description yet. This curated deck is ready for daily study.
Card preview (19)
State the colours of the oxidation states of vanadium (+5, +4, +3 and +2) in its compounds.
+5: Yellow (VO2+) +4: Blue (VO2+ +3: Green (V3+) +2: Violet (V2+)
Describe the reduction of the dichromate(VI) ion, Cr2O72−.
Reduced to Cr3+ and Cr2+ ions, Using zinc in acidic conditions.
Describe a method to produce the dichromate(VI) ion, Cr2O72−.
Oxidation of Cr3+ ions, Using hydrogen peroxide in alkaline conditions (followed by acidification).
Give the equilibrium equation that results in the conversion of the dichromate(VI) ion, Cr2O72−, into chromate(VI) ions.
2CrO42− + 2H+ ⇌ Cr2O72− + H2O
Write an ionic equation for the reaction of the complex ion, [M(H2O)x]y+, with aqueous sodium hydroxide, and state the type of reaction.
[M(H2O)x]y+ + yOH- → [M(H2O)x-y(OH)y] + yH2O Proton transfer
Write an ionic equation for the reaction of the complex ion, [M(H2O)x]y+, with aqueous ammonia, and state the type of reaction.
[M(H2O)x]y+ + yNH3 → [M(H2O)x-y(OH)y] + yNH4+ Proton transfer
Define the term amphoteric
Can act as an acid or a base
Describe the difference between ligand exchange and amphoteric behaviour in terms of the reactions of aqueous complex ions with NaOH or NH3.
Amphoteric behaviour: H2O ligands are deprotonated by the base, so the complex ions acts as an acid. Ligand exchange: NH3 ligands exchange with H2O ligands.
Reaction of aqeous copper(II) ions with concentrated hydrochloric acid: Product, Colour change, Type of reaction.
[CuCl4]2-, Blue -> green, Ligand exchange.
Reaction of aqeous cobalt(II) ions with concentrated hydrochloric acid: Product, Colour change, Type of reaction.
[CoCl4]2-, Pink -> blue, Ligand exchange.
Describe a reaction that can lead to a change in coordination number.
The substitution of small, uncharged ligands (such as H2O) by larger, charged ligands (such as Cl−).
Explain why the substitution of a monodentate ligand by a bidentate or multidentate ligand leads to a more stable complex ion.
The small ligands are released and have greater freedom of movement, so there is a large positive increase in ΔSsystem.
Describe a heterogeneous catalyst
The catalyst is in a different phase from the reactants, The reaction occurs at the surface of the catalyst.
Describe the contact process.
Converts oxygen and sulfur dioxide to sulfur trioxide. Catalyst: V2O5
State the role of a catalytic converter
Decreases carbon monoxide and nitrogen monoxide emissions from internal combustion engines
Describe how a catalytic converter works
• Adsorption of CO and NO molecules onto the surface of the catalyst, • Bonds are weakened so a chemical reaction can occur, • Desorption of CO2 and N2 product molecules from the surface of the catalyst.
Describe a homogeneous catalyst
The catalyst is in the same phase as the reactants, The catalysed reaction will proceed via an intermediate species.
State the catalyst for the reaction between I− and S2O82− ions
Fe2+ ions
State the catalyst and the type of catalysis for the reaction between MnO4− and C2O42− ions
Mn2+ ions, Autocatalysis