NTA Abhyas NEET2020ChemistryChemical EquilibriumPractice
An aqueous solution contains 0.10 M H 2 S and 0.20 M HCl. If the equilibrium constants for the formation of H S – from H 2 S is 1.0 × 1 0 - 7 and that of S 2 - from H S - ions is 1.2 × 1 0 - 13 then the concentration of S 2 - ions in aqueous solution is
Options
- A5 × 1 0 - 19
- B5 × 1 0 - 8
- C3 × 1 0 - 20
- D6 × 1 0 - 21
Correct answer
C. 3 × 1 0 - 20
Step-by-step solution
H 2 S ( a q ) ( 0.1 - x ) = 0.1 ⇌ 2 H + ( 2 x + 0.20 ) ≃ 0.2 + S 2 - x , K a = K a 1 = 1.2 × 1 0 - 20 1.2 × 1 0 - 20 = ( 0.2 ) 2 × [ S 2 - ] 0.1 [ S 2 - ] = 3 × 1 0 - 20 '