[alexa95]

Codeine (C18H21NO3) is a weak base with Kb=1.6 x 10^-6 . 50ml of a 0.1M solution of codeine is acidified by addition of 60.0ml of a 0.05M HCl solution. Determine the pH of the resulting solution.

[Arkcon]

Welcome to the chemicalforums, alexa95:, please trouble yourself to read the Forum Rules{click}.  We don't give complete answers on this forum.  Show us what you've done so far to try and solve this problem yourself.  If you assume the codeine and acidified codeine are making a buffer, do you have an idea of what formula to use?