Chemistry - Chemical Equilibrium Question with Solution | TestHub
ChemistryChemical EquilibriumProblems involving KcMedium2 minQB
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Find the concentration of monomeric benzoic acid in a CCl4 solution which contains 0.0244 g of the acid in 200 ml of solution. The dissociation constant of the dimeric acid is 2.5 × 10-4. Assume that the acid is unionized in CCl4 solution.
Options:
Answer:
B
Solution:
Molar mass of C6H5COOH = 122 g/mol, so total acid = 0.0244/122 = 2 × 10-4 mol in 200 ml = 10-3 M For dimer ⇌ 2 monomer: if m = [monomer], [dimer] = (10-3 - m)/2
m2/[(10-3 - m)/2] = 2.5 × 10-4 gives 2m2 + 2.5 × 10-4m - 2.5 × 10-7 = 0
m = [-2.5 × 10-4 + √((2.5 × 10-4)2 + 2 × 10-6)]/4 = 2.96 × 10-4 ≈ 3.0 × 10-4 M
This is option (b).
Stream:JEESubject:ChemistryTopic:Chemical EquilibriumSubtopic:Problems involving Kc
⏱ 2mℹ️ Source: QB
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