How many chlorides can silver find?
"How many chlorides can silver find?" is a free, interactive Class 12 Chemistry simulation for NEET and JEE, built on the lesson "Werner's theory" in Coordination Compounds. Pick one of Werner's cobalt(III) chloride ammines and slide in AgNO₃, counted as moles of Ag⁺ per mole of complex. White AgCl settles only while there is free chloride to meet. Watch where the graph goes flat. Moles of AgCl count the chlorides outside the square bracket: 3, 2, 1 for 6, 5, 4 NH₃. The coordination number stays 6 throughout; each NH₃ lost is replaced by a chloride that stops being ionisable. JEE Main asked 80 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Werner's theory in Coordination Compounds. Change the values and watch what happens.
In JEE Main
42 shifts analysed
80 questions from Coordination Compounds across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT §5.1
- A coordination compound holds a central metal atom or ion joined to a set of anions or neutral molecules through shared electron pairs. Chlorophyll (Mg), haemoglobin (Fe) and vitamin B12 (Co) are all coordination compounds.
- Werner tested the cobalt(III) chloride-ammonia compounds with excess cold AgNO₃. Per mole: CoCl₃·6NH₃ (yellow) gave 3 mol AgCl, CoCl₃·5NH₃ (purple) gave 2, and both forms of CoCl₃·4NH₃ (green and violet) gave 1.
- He explained this by keeping six groups (Cl⁻, NH₃ or both) fixed on the cobalt in a unit that does not break up: [Co(NH₃)₆]Cl₃ is a 1:3 electrolyte, [CoCl(NH₃)₅]Cl₂ a 1:2 electrolyte and [CoCl₂(NH₃)₄]Cl a 1:1 electrolyte, as their conductivities confirm.
- Only chloride outside the square bracket is free to meet Ag⁺; chloride bonded to the metal inside the bracket is not precipitated.
- The green and violet CoCl₃·4NH₃ share one empirical formula but differ in properties, so they are isomers.
- Werner's postulates (1898): a metal shows primary and secondary valences. Primary valences are ionisable and satisfied by negative ions. Secondary valences are non-ionisable, satisfied by neutral molecules or anions, equal to the coordination number and fixed for a given metal.
- The groups held by secondary valences have a definite arrangement in space for each coordination number, today called the coordination polyhedron. The bracketed species is the complex; ions outside are counter ions.
- Common shapes: [Co(NH₃)₆]³⁺, [CoCl(NH₃)₅]²⁺ and [CoCl₂(NH₃)₄]⁺ are octahedral, [Ni(CO)₄] is tetrahedral and [PtCl₄]²⁻ is square planar.
- A double salt such as carnallite (KCl·MgCl₂·6H₂O), Mohr's salt (FeSO₄·(NH₄)₂SO₄·6H₂O) or potash alum breaks up completely into simple ions in water. A complex does not: K₄[Fe(CN)₆] gives [Fe(CN)₆]⁴⁻, not Fe²⁺ and CN⁻.
Questions
3 answers
- What does the "How many chlorides can silver find?" simulation show?
- Pick one of Werner's cobalt(III) chloride ammines and slide in AgNO₃, counted as moles of Ag⁺ per mole of complex. White AgCl settles only while there is free chloride to meet. Watch where the graph goes flat.
- Does JEE Main ask questions from Coordination Compounds?
- Yes. JEE Main asked 80 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Werner's theory" in Coordination Compounds (Class 12 Chemistry).
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