JEE Main20199 Jan 2019Morning ShiftChemistryIonic EquilibriumActual
20   ml of 0.1 M H 2 SO 4   solution is added to 30   mL of 0 .2   M   NH 4 OH solution. The pH of the resultant mixture is: pk b of NH 4 OH = 4 .7
Options
- A5.0
- B5.2
- C9.4
- D9.0
Correct answer
D. 9.0
Step-by-step solution
Millimoles of H 2 S O 4 = 20 × 0.1 = 2 Millimoles of N H 4 O H = 30 × 0.2 = 6 Hence, the solution will act as a basic buffer. p O H = p K b + l o g s a l t B a s e N H 4 + = 2 × N H 4 2 S O 4 ;                   N H 4 + = 4 p O H = p K b + l o g N H 4 + N H 3 = 4.7 + l o g 4 2 = 4.7 + 0.3010 = 5.010 p H = 14 - p O H = 9