Calculate the pH at 25°C of a 0.25 M aqueous solution of phosphoric acid (H3PO4). For H3PO4, Ka1 = 7.3  10-3 , Ka2 = 6.2  10-8 , and Ka3 = 4.8  10-13Calculate the pH at 25°C of a 0.25 M aqueous solution of phosphoric acid (H3PO4). For H3PO4, Ka1 = 7.3  10-3 , Ka2 = 6.2  10-8 , and Ka3 = 4.8  10-13