Question

1). Consider a 0.4 M solution of   anilinium chloride. The ion   anilinium is the conjugate acid of the the weak base aniline.The pKb   of aniline is 9.13  

Part a).   Calculate  [H+] __________ M

Part b). Calculate the concentration of   anilinium ions. __________ M

Part c). Calculate the concentration of   aniline in equilibrium. _________ M

Part d). Calculate [OH−] ________ M

Part e). Calculate [Cl^-] ________ M

Part f). Calculate the pH _______ M

2). Calculate the pH and the concentration [Na+] =of all species in   3.5×10⁻²   molar sodium cyanide solution.

[Na+] = ___ M

H+] = ___M

pH = ___M

[OH−] =___M

[CN−] = ___M

[HCN]= ___M

Answer 1

1). Consider a 0.4 M solution of   anilinium chloride. The ion   anilinium is the conjugate acid of the the weak base aniline.The pKb   of aniline is 9.13  

BHCl --> BH+ + Cl-

BH+ ---> B + H+

Ka = [B][H+]/[BH+]

Kw/Kb = x*x/(0.4-x)

(10^-14)/(10^-9.13) = x*x/(0.4-x)

x = 0.002316

[B] = [H+]= x= 0.002316

[BH+] = 0.4-0.002316 = 0.3977

Part a).   Calculate  [H+] __________ M

[H+] = 0.002316

Part b). Calculate the concentration of   anilinium ions. __________ M

[BH+] = 0.4-0.002316 = 0.3977 M

Part c). Calculate the concentration of   aniline in equilibrium. _________ M

[B] = [H+]= x= 0.002316 M

Part d). Calculate [OH−] ________ M

[OH-] = (10^-14) / (0.002316) = 4.31*10^-12

Part e). Calculate [Cl-] ________ M

[Cl-] = 0.4 M

Part f). Calculate the pH _______ M

pH = -log(0.002316) = 2.64