Finding pH of Weak Acid Given Initial Conc (6D #13b)

[Meagan Kimbrell 1I]

Focus 6d
#13 part b) Find pH of 0.20M CH3NH3Cl (aq).
I am having trouble setting up the reaction to set up an ICE box...
I was able to ultimately get the correct value of the pH but I know I set it up wrong as my equation was CH3NH3Cl <--> CH3NH2+ = Cl-, and there is obviously no [H+] in here to plug when solving for pH.
Could someone clarify the correct set-up for the ICE box?

[Autumn Jackson Dis 1J]

The correct reaction equation is Ch3NH3+ + H20 = CH3NH2 + H30+ . This is because CH3NH3Cl disassociates into CH3NH3+ and Cl-. The Cl- is a spectator ion, so CH3NH3+ is left to react as an acid. To find the Ka of this acid, find the Kb of CH3NH2 and divide 10^-14 by it (10^-14 = Ka * Kb). From there you have you can get your ice box from the previous equation.