6. (A) Calculate the pH of 0.500 M benzoic acid solution. (10 points)(B) Calculate the pH after 20.0 mL of 1.00 M NaOH was added to 50.0 mL of 0.500 M benzoicacid solution. (C6H5COOH, Ka = 6.28×10-5)

7. For the following cell: Cu(s)|Cu2+(0.0250M)||Fe3+(0.150M), Fe2+(0.0380M)|Pt(s). E0(Cu2+→Cu) = 0.34 V, E0(Fe3+→Fe2+) = 0.77 V (10 points)(A) Write the oxidation and reduction half-reactions.(B) Calculate the cell potential, Ecell at 25oC, and tell if the cell reaction is spontaneous.