Use the following information: Phosphate buffer system is an important buffer present in biological systems. This buffer in the lab can be prepared by mixing monosodium dihydrogen phosphate and disodium hydrogen phosphate in appropriate amounts. Sodium is a spectator ion; it does not take part in reaction. Note that NaH2PO4 produces the same number of moles of H2PO4. The same is true for the other compound. Based on these pieces of information, answer the following questions (5-11): 5. Calculate the pH of the solution if you add 0.020 moles of H2PO4and 0.010 moles of HPO42 (3) 6. Calculate the pH of the solution if you add 0.010 moles of H2PO4and 0.020 moles of HPO42 (2) 7. Calculate the pH of the solution if you add 0.020 moles of H2PO4and 0.020 moles of HPO42 (2) 8. Calculate the ratio of moles of H2PO4to the moles of HPO42 in a solution having a pH of 5.60. (2) 9. Calculate the ratio of moles of H2PO4to the moles of HPO42 in a solution having a pH of 6.60. (2) 10. Calculate the ratio of moles of HPO42 to moles of in H2PO4a solution having a pH of 7.60. (1) 11. Suppose you prepared a buffer by dissolving 15.20gm of monosodium dihydrogren phosphate and 10.20gm disodium hydrogen phosphate in 200.mL of water. Calculate the pH of the resulting solution. (2) 12. The pKa of the following reaction is 7.20, and the pH of human blood is 7.4. Calculate the ratio of HPO42 to H2PO4in the human blood. (3) H2PO4H++HPO42