The ph of a 0.24 m solution of dimethylamine is 12.01. calculate the kb value for dimethylamine.

1- First we will get the value of POH from:

PH + POH = 14 

and we have PH = 12.01

∴ POH = 14 - 12.01 = 1.99 

2- Then we need to get the concentration of OH:

when POH = -㏒[OH]

           1.99 = -㏒[OH]

∴[OH] = 0.01 M

now we have the concentration at Equ by subtracting from the initial concentration of OH  = 0.24 M

∴ [OH] = 0.24 - 0.01 = 0.23 M

∴ Kb = (0.01)^2 /  0.22977 M

∴ Kb value = 4.4 x 10^-4

The answer is a) carbon-12

Ci hope  it  you