# When a general base associates in water, with #K_b# #"<<"# #10^(-5)#, what is the algebraic expression for #x# as a function of #K_b# and the equilibrium concentration of the base?

##### 1 Answer

Mar 9, 2017

As usual, write out the reaction.

#"B"(aq) + "H"_2"O"(l) rightleftharpoons "OH"^(-)(aq) + "BH"^(+)(aq)#

By constructing an ICE table, you would obtain:

#K_b = (["OH"^(-)]["BH"^(+)])/(["B"]) = x^2/(["B"] - x)#

As

#color(blue)(x ~~ sqrt(K_b["B"]))#

And you can always use this expression for a weak base equilibrium in which

Did you check your answer by trying to see if the