Chemistry - Mole Concept Question with Solution | TestHub

ChemistryMole ConceptMiscellaneous/MixedEasy2 minPYQ_2020
ChemistryEasysingle choice

A complex of cobalt with ammonia is analyzed for determining its formula, by titrating it against a strandarized acid as follows :
CoNH3xClyaq+HClNH4+aq+Coy++aq+ClaqA 1.8 g complex required 20.00 mL 1.54 M HCl to reach the equivalence point. Also, if the reaction mixture at equivalence point is treated with excess of AgNO3solution, 7.735 g of AgCl precipitate was produced. What is the formula of this complex?
[Given: atomic weight of CO = 59 gmol-1]

Options:

Answer:
A
Solution:

Co(NH3)xCly1.8M+xHCL1.8MxNH4+aq+Coy++(x+y)Cl-1.8(x+r)M

1 . 8 x M = 2 0 × 1 . 5 4 × 1 0 - 3 = 3 0 . 8 × 1 0 - 3 ........(I)

1 · 8 x + y M = 7 . 7 3 5 1 4 3 . 5 = 5 3 . 9 × 1 0 - 3 ........(II)

II I  ⇒  5 3 . 9 × 1 0 - 3 3 0 . 8 × 1 0 - 3 = 1 . 7 5 = x + y x = 1 + y x

y x = 0 . 7 5

Substituting in (I)

1 . 8 x 5 9 + 1 7 x + 3 5 . 5 × 0 . 7 5 x = 3 0 . 8 × 1 0 - 3

x = 3.98 = 4 y = 3

Stream:NTA_ABHYASSubject:ChemistryTopic:Mole ConceptSubtopic:Miscellaneous/Mixed
2mℹ️ Source: PYQ_2020

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