Question

A certain weak base has a Kb of 7.40 × 10-7. What concentration of this base will produce a pH of 10.17?

__?__ M

Answer 1

We are given pH and kb value of weak base. Weak base can be assumed to be B and then its reaction is shown with water, it abstracts the proton from water and produce OH- . Equilibrium concentration of OH- is calculated by using pH.

By setting ICE we can get unknown concentration of base.

By using pOH, pH is calculated.

Step 1 : Calculate concentration of hydroxide ion.