In: Chemistry
A 40.8 mL sample of a 0.582 M aqueous nitrous acid solution is titrated with a 0.285 M aqueous potassium hydroxide solution. What is the pH after 56.5 mL of base have been added?
no of moles of HNO2 = molarity * volume in L
= 0.582*0.0408 = 0.0237456 moles
no of moles of KOH = molarity * volume in L
= 0.285*0.0565 = 0.0161025 moles
HNO2 (aq) + KOH(aq) ---------------> KNO2(aq) + H2O(l)
I 0.0237456 0.0161025 0
C -0.0161025 -0.0161025 0.0161025
E 0.0076431 0 0.0161025
Pka = 3.15
[KNO2] = 0.0161025mole
[HNO2] = 0.0076431moles
PH = PKa + log[KNO3]/[HNO2]
= 3.15 + log0.0161025/0.0076431
= 3.15 + 0.3236
= 3.4736>>>>>answer