The ionisation constant of NH3 is k=1.8*10^-5. Calculate K for its conjugate acid NH^4
The ionization constant, Ka, of NH3 can be expressed as follows:
Ka = [NH4+][OH-] / [NH3]
The ionization constant Kb can be calculated using the following relationship:
Kb = Kw / Ka
Where Kw is the ionization constant of water, which is equal to 1.0 x 10^(-14) at 25°C.
We are given Kb for NH3:
Kb(NH3) = 1.8 * 10^(-5)
We want to calculate Ka for its conjugate acid, NH4+.
Ka(NH4+) = Kw / Kb
Ka(NH4+) = (1.0 * 10^(-14)) / (1.8 * 10^(-5))
Ka(NH4+) = 5.56 * 10^(-10)
So, the ionization constant, Ka, for the conjugate acid NH4+ is approximately 5.56 * 10^(-10).