CCEA A-Level Chemistry 1110
Formulae, Equations and Amounts of Substance
Atomic Structure
Bonding
Intermolecular Forces and Structure
Shapes of Molecules and Ions
Redox
The Halogens
Acid-Base Titrations
Qualitative Tests
Formulae and Amounts of a Substance
Nomenclature and Isomerism in Organic Chemistry
Alkanes
Alkenes
Halogenoalkanes
Alcohols
Infrared Spectroscopy
Energetics
Kinetics
Equilibrium
Group II Elements and Their Compounds
Lattice Enthalpy, Entropy and Free Energy
Rates of Reaction
Equilibrium and Acid-Base Equilibria
Isomerism
Aldehydes and Ketones
Carboxylic Acids
Derivatives of Carboxylic Acids
Aromatic Chemistry
Spectroscopy and Chromatography
Volumetric Analysis
Transition Metals
Electrode Potentials
Amines
Amides and Polymers
Amino Acids and Proteins
Transition Metals
Vanadium and the interconversion of its oxidation states
- 3 things to know
- Unit A2 2
Overview
Recall questions on acidified ammonium metavanadate as the source of vanadium(V), the yellow to blue to green to violet sequence with zinc and the species and oxidation state behind each colour, the three half-equations and their potentials, why zinc reduces all the way, and choosing a reducing agent from a table of potentials.
What you need to know
Answer each one before you reveal it.
What reagent is used to reduce vanadium(V) through its lower oxidation states?
Give the sequence of colours observed as zinc reduces acidified ammonium metavanadate.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What compound is used as the source of vanadium(V) in the laboratory?
Model answer
Ammonium metavanadate, acidified to give the yellow dioxovanadium(V) ion.
- 2
Give the formula of the vanadium(V) species in acid solution.
Model answer
VO₂⁺.
- 3
What reagent is used to reduce vanadium(V) through its lower oxidation states?
Model answer
Zinc metal, in the presence of acid.
- 4
Give the sequence of colours observed as zinc reduces acidified ammonium metavanadate.
Model answer
Yellow to blue to green to violet.
- 5
Name the species responsible for each of those colours.
Model answer
Yellow is VO₂⁺, blue is VO²⁺, green is V³⁺ and violet is V²⁺.
- 6
Give the oxidation states corresponding to that sequence.
Model answer
Plus five, plus four, plus three and plus two.
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