Answer
$C_3H_7NH_2 + H_2O -> {C_3H_7NH_3}^+ + OH^-$
$Kb = \frac{[{C_3H_7NH_3}^+][OH^-]}{[C_3H_7NH_2]}$
Work Step by Step
1. Write the reaction:
$C_3H_7NH_2 + H_2O -> {C_3H_7NH_3}^+ + OH^-$
2. Now, write the Kb formula:
$Kb = \frac{[Conjugate.Acid]*[OH^-]}{[Base]}$
$Kb = \frac{[{C_3H_7NH_3}^+][OH^-]}{[C_3H_7NH_2]}$