Exam #4 Key

4. On the basis of the information above, a buffer with a pH = 9 can best be made by usingAcidH 3 PO 4-H 2 PO 4HPO 42-K a7 10 38 10 85 10 13A. pure NaH 2 PO 4 .B. H 3 PO 4 + H 2 PO 42-C. H 2 PO 4 - + PO 4 3- .D. H 2 PO 4 - + HPO 4 2- .E. HPO 4 2- + PO 4 3- .Answer:____D______5. For which type of titration will the pH be basic at the equivalence point?A. Strong acid vs. strong base.B. Strong acid vs. weak base.C. Weak acid vs. strong base.D. All of the above.E. None of the above.Answer:____C______6. The normal freezing point of ammonia is 78C. Predict the signs of H, S, and G forammonia when it freezes at 80C and 1 atm: NH 3 (l) NH 3 (s)H S GA. - - 0B. - + -C. + - +D. + + 0E. - - -Answer:____E______4