Adapted by Nelson Nuñez-Rodriguez
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By David W. Ball
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| QUESTION | ANSWER |
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1. Define buffer. What two related chemical components are required to make a buffer? |
1. A buffer is the combination of a weak acid or base and a salt of that weak acid or base. |
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3. Which combinations of compounds can make a buffer? Assume aqueous solutions.
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3.
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5. For each combination in Exercise 3 that is a buffer, write the chemical equations for the reactions of the buffer components when a strong acid and a strong base is added. |
5. 3b: strong acid: NO2− + H+ → HNO2; strong base: HNO2 + OH− → NO2− + H2O; 3d: strong base: NH4+ + OH− → NH3 + H2O; strong acid: NH3 + H+ → NH4+ |
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7. The complete phosphate buffer system is based on four substances: H3PO4, H2PO4−, HPO42−, and PO43−. What different buffer solutions can be made from these substances? |
7. Buffers can be made from three combinations: (1) H3PO4 and H2PO4−, (2) H2PO4− and HPO42−, and (3) HPO42− and PO43−. (Technically, a buffer can be made from any two components.) |
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9. Two solutions are made containing the same concentrations of solutes. One solution is composed of H3PO4 and Na3PO4, while the other is composed of HCN and NaCN. Which solution should have the larger capacity as a buffer? |
9. The phosphate buffer should have the larger capacity. |