Determine the [h3o+] of a 0.210 m solution of formic acid.

When the Pka for formic acid = 3.77
and Pka = -㏒ Ka 
   3.77 = -㏒ Ka
∴Ka = 1.7x10^-4 

when Ka = [H+][HCOO-}/[HCOOH]

when we have Ka = 1.7x10^-4 &[HCOOH] = 0.21 m
so by substitution: by using ICE table value
1.7x10^-4 = X*X / (0.21-X)
(1.7x10^-4)*(0.21-X) = X^2      by solving this equation for X

∴X = 0.0059
∴[H+] = 0.0059
∴PH= -㏒ [H+]
       = -㏒ 0.0059
       = 2.23 

Okay well gravitational energy is matter forced by gravity making energy though the kinetic energy then the electric energy produces electricity from the kinetic energy and the kinetic energy gets its energy from the gravitational energy. was that the answer you wanted or something else?