Question

Hydrazine, N2H4, is a weak base and is used as fuel in the space shuttle.

N2H4(aq)+H2O(l)âN2H5+(aq)+OHâ(aq)

Part A

If the pH of a 0.133 M solution is 10.66, what is the ionization constant of the base?

Express your answer using two significant figures.

Answer 1

Kb = 1.6*10^-6

Step-by-step explanation:

The given reaction is:

`N2H4(aq)+H2O(l)\rightarrow N2H5+(aq)+OH-(aq)`

The ionization constant of the base Kb is given as:

`Kb = ([N2H5+][OH-])/([N2H4])------(1)`

The pH = 10.66

therefore, pOH = 14-pH = 14-10.66 =3.34

`[OH-] = 10^(-pOH) =10^(-3.34) =4.57*10^(-4) M`

[N2H5+] = [OH-] = 4.57*10^-4M

[N2H4] = 0.133 M

Based on eq(1)

`Kb = ([4.57*10^(-4)]^(2))/([0.133])=1.6*10^(-6)`