Waec Model Questions Vol1 2022 Chemistry Question 4

Practice essay / theory question 4 from the 2022 Waec Model Questions Vol1 Chemistry examination. This question covers mole concept, coordination chemistry, empirical formula, percentage composition, isomerism .

Waec Model Questions Vol1 2022 Chemistry Essay / Theory
Topics: mole concept coordination chemistry empirical formula percentage composition isomerism
Question 4 WAEC_MODEL_QUESTIONS_VOL1 • 2022 • CHEMISTRY • essay

The diagram shows an octahedral coordination complex. The central metal ion is cobalt (Co). Two ammonia (NH₃) ligands are positioned cis to each other, two chloride (Cl⁻) ligands are positioned trans to each other, a water (H₂O) ligand is trans to a nitro (NO₂⁻) ligand. The complex ion carries an overall charge of +1 and the compound is isolated as its chloride salt with two molecules of crystallisation water, giving the formula [Co(NH₃)₂Cl₂(H₂O)(NO₂)]Cl·2H₂O.

Question Parts

( a )
Determine the oxidation state of the cobalt ion in the complex.
( b )
Write the empirical formula of the isolated salt, including the waters of crystallisation.
( c )
Calculate the percentage by mass of cobalt in the compound. (Use atomic masses: Co = 58.93 g mol⁻¹, Cl = 35.45 g mol⁻¹, N = 14.01 g mol⁻¹, H = 1.008 g mol⁻¹, O = 16.00 g mol⁻¹.)
( d )
The complex exhibits ionisation isomerism. Write the formula of the ionisation isomer and briefly explain how it differs from the given compound.

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About This Question

This is Waec Model Questions Vol1 2022 Chemistry Question 4. It is one of the essay questions from the 2022 Waec Model Questions Vol1 Chemistry examination.

The question covers mole concept, coordination chemistry, empirical formula, percentage composition, isomerism .

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