posted by Kimmytuma on .
A sample of 8.00 L of NH3 (ammonia) gas at 22 degrees and 735 torr is bubbled into a 0.500 L solution of 0.400 M HCl (hydrochloric acid). The Kb value for HCl is 1.8x10^-5. Assuming all the NH3 dissolves and that the volume of the solution remains at 0.500 L, calculate the pH of the resulting solution. (need some help kinda don't know where to start)
You need to proof your post. I might believe Kb for NH3 is 1.8E-5 but not Kb for HCl???
Sorry yes you are correct. The Kb is for NH3!
Use PV = nRT and solve for n = number of mols NH3 at the conditions listed. Remember P is in atmospheres and T is in kelvin.
Find mols HCl. That is M x L = ?
Subract moles HCl - mols NH3 to find excess NH3 that doesn't react. This leaves you with a buffer solution consisting of NH3 and NH4Cl.
Plug these values into the Henderson-Hasselbalch equation and solve for pH.