Coordination compounds: Werner's experiment, naming and isomers
ChemistryInorganic ChemistryAges 17–18Virtual lab
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Inorganic Chemistry
Three screens on cobalt(III) complexes. Repeat Werner's experiment: weigh the AgCl precipitated from CoCl₃·6NH₃, CoCl₃·5NH₃ and two forms of CoCl₃·4NH₃, and measure conductivity, to find how many Cl⁻ ions lie outside the coordination sphere. Build the IUPAC names of complexes. Turn 3D models of cis–trans, fac–mer, Δ and Λ optical, linkage and ionisation isomers.
Lesson: Coordination compounds: Werner's theory, IUPAC naming and isomerism
What it shows
In 1893 Alfred Werner explained the compounds CoCl₃·xNH₃ with a coordination sphere: the metal ion is bonded directly to a set of ligands, and the remaining ions sit outside the sphere. Only chloride outside the sphere precipitates at once as AgCl with silver ions, and the number of ions in solution sets the molar conductivity. The IUPAC name of a complex lists the ligands in alphabetical order with multiplying prefixes, then the metal, its oxidation number and -ate for a complex anion. Octahedral complexes show geometric, optical, linkage and ionisation isomerism.
How to use
In Werner's experiment, choose the Sample, Sample mass and AgNO₃ volume, press Precipitate and weigh AgCl, then Measure conductivity; the readings go into the tables. In Naming, choose a Complex, pick the prefixes, ligands, metal and oxidation number, then press Check. In Isomers, choose a pair, drag to turn the models, and press Measure angles or Put B on A.
Parameters you can change
- Screen Werner's experiment, Naming, Isomers
- Sample CoCl₃·6NH₃ (yellow), CoCl₃·5NH₃ (purple), CoCl₃·4NH₃ (green), CoCl₃·4NH₃ (violet)
- Sample mass 0.2–1 g
- AgNO₃ volume 5–100 cm³
- Complex [Co(NH₃)₆]Cl₃, [CoCl(NH₃)₅]Cl₂, trans-[CoCl₂(NH₃)₄]Cl, [Co(en)₃]Cl₃, trans-[CoCl₂(en)₂]Cl, [Co(NH₃)₅(NO₂)]Cl₂, [Cr(H₂O)₆]Cl₃, [Cu(NH₃)₄(H₂O)₂]SO₄, K₃[Fe(CN)₆], K₄[Fe(CN)₆], K₂[PtCl₄], cis-[PtCl₂(NH₃)₂], [Ni(CO)₄], Na[Ag(CN)₂]
- Isomer pair cis–trans, fac–mer, Optical, Linkage, Ionisation, Same, turned
Questions to explore
- With 0.50 g of each sample, what mass of AgCl do you collect, and what is the mole ratio of AgCl to sample?
- Why do green and violet CoCl₃·4NH₃ give the same mass of AgCl and the same conductivity?
- No rotation puts Λ-[Co(en)₃]³⁺ exactly on Δ-[Co(en)₃]³⁺; what happens with the two cis models?
