Kb in chemistry is the dissociation constant?

1>from equstion pkb=-log(kb),this for basic drug,p indicat power of basic drug to dissociate.

pKb (using the same system as pH) = -logKb

(p stands for 'potenz' - the german word for 'power')

Kp is the equilibrium constant in terms of partial pressures (so obviously is restricted to gaseous systems)

Kc is in terms of concentrations.

So, for the gaseous equilibrium H2(g) + I2(g) <=> 2HI(g)

Kp = (p(HI)^2)/(p(H2) X p(I2))     Kc = ([HI]^2)/([H2] X [I2])

The "p" in pH may have some obscure meaning related to "power", but today "p" takes on an entirely different meaning when applied to other variables.  Think of "p" as meaning "the negative log of ...".

pH = the negative log of the hydrogen ion concentration
pKa = the negative log of the acid dissociation constant
pKb = the negative log of the base dissociation constant
pKw = the negative log of Kw
p-whatever = the negative log of whatever

Kc is the equilibrium constant using concentration units (molarity)
Kp is the equilibrium constant using pressure units (atm)
Kp = Kc(RT)^Dn ....  where R is the gas constant, 8.314 J/molK, T is the absolute temp, Dn is the difference in moles, Dn = moles of gaseous products - moles of gaseous reactants