a. pH = pKa + log(base)/(acid)
pH = 3.75 + log(x)/(x) (the problem just says base = acid so I've called that x.
pH = 3.75 + log(1)
pH = 3.75 + 0
pH = 3.75
HCOOH = formic acid = acid = 1.0M
HCOONa = sodium formate = base = 10M
pH = 3.75 + log (10)/(1)
Solve for pH You should get 4.75.
Acids/bases are described with the Bronsted-Lowry theory as
HA = acid
HA + H2O ==> H3O^+ + A^-
HA is the acid and A^- is its conjugate base.
H2O is the base and H3O^+ is its conjugate acid.
How do you know which is which? The acid is the one with more atoms; the base is the one with fewer H atoms. Look at HA. HA and A. HA is the acid because it has more H atoms than the A. A is the base becasuse it has fewer H atoms than HA.
H2O/H3O^+. H3O^+ has more H atoms; it's the acid. H2O has fewer H atoms; it's the base.