Question

HY102 F2016 Test 2 crystallizes in a face-centred cubic structure with an edge length of 202 r. A) 440 pm B) 110 pm C) 143 pm 8) A 100.0 mL sample of 0.10 mol L-1 pyridine (C5H5N, Kb of NH3 is 1.7 - 10-9) is titrated with 0.10 mol L-1 HNO3 at 25 °C. Determine the pH of the solution after the addition of 100.0 mL of HNO3. A) 5.04 B) 7.00 C) 5.38 D) 3.27 E) 8.77 9) Consider the following reaction and its equilibrium constant: A(g) + B() 2C(8) + D(8) Kc=0.25

Answer 1

mmoles of base = B = 100 x 0.1 = 10

HNO3 mmoles = H+ = 100 x 0.1 = 10

it is equivlanece point .here only salt left

salt concentration = 10 / 100 + 100 = 0.05 M

pKb = -log Kb = 8.77

pH = 7 - 1/ 2[pKb + log C]

pH = 7 - 1/2 [8.77 + log 0.05 ]

pH   = 3.27

answer : D ) 3.27