Calculate the pH of each of the following solutions.
a. 0.100 M propanoic acid (HC₃H₅O₃, Ka 1.3 105 )
b. 0.100 M sodium propanoate (NaC₃H₅O₃)
c. pure H₅O
d. a mixture containing 0.100 M NaC₃H₅O₃ and 0.100 M NaC₃H₅O₃