Buffer Post Lab

Buffer Post Lab

Calculation 1. We added too much NaOH to our buffer 1 solution. The original pH was 5.32, with 10mL of buffer and 10mL of DI water. We added 5mL of NaOH and the pH changed to 12.12. If 5 mL changed the pH by about 7, then we predict that about 2 mL of NaOH would change the pH by about 2. This prediction is based on the fact that 2.5mL is half of 5mL, and 3.5 is half of 7, so adding a little less than 2.5mL would give us a difference of about 2. For the buffer 2 solution, the original pH was 5.82 with 10mL of buffer and 10mL of DI water. We added 1.5mL of NaOH this time, and the pH went up to 7.81. This is a difference of 2. 2. What is the difference between a'smart' and a'smart'? For adding HCl, we started with buffer 1. The
Our buffer 1 solution has a lower pH than our buffer 2 solution. Buffer 1 has a pH of 5.12 while buffer 2 has a pH of 5.66. This would be because buffer 1 has a higher concentration of acid. Buffer 1 contained 12mL of acetic acid and 34mL of sodium acetate, while buffer 2 contained only 3mL of acetic acid, and 44mL of sodium acetate. Buffer 1’s pH would be lower because it contains a higher amount of acid, on top of a lower amount of base, as compared to the amounts of acid and base in the buffer 2 solution. 2. What is the difference between a'smart' and a'smart'? Buffer 1 requires about 2 mL of NaOH to change by 2 units, so it would have needed about 1 mL of NaOH to change by one unit. Buffer 2 however required only 1.5mL of NaOH to change by 2 units, so it would have needed about 0.75 mL of NaOH to change by 1 unit. The reason that buffer 1 requires more NaOH to change by 1 unit than buffer 2 does, is because of the fact buffer 1 was more acidic to begin with and had a lower initial pH. Therefore, it takes more NaOH to dilute the acid and make it more basic with a pH that is now 2 units higher. Buffer 2 didn’t require as much NaOH because it already had a slightly higher pH to begin with. 3. What is the difference between a'smart' and a'smart'? Our buffer 1 solution required about 6.7mL of HCl to change by 2 units, so it would have required about 3.35mL of HCl to change by 1 unit, since 3.35 is half of 6.7. Our buffer 2 solution required about 9mL of
This is because buffer 2 had a higher initial pH than buffer 1, meaning it was more basic to start with. It is harder for a solution with a higher pH to become more acidic, than one with a lower pH that is already a bit more acidic to begin with. 4. What is the difference between a.. 10mL of DI water changed each of our buffer solutions by only about 0.2 units, which is hardly a difference. However, when we added NaOH to our buffers, only 5 mL of NaOH caused a difference of 7 whole units in buffer 1, and only 1.5 mL of NaOH caused a difference of 2 units in buffer 2. This means that our solutions had a much easier time resisting pH changes with DI water than they did with NaOH. The NaOH had a massive impact on the pH of the solution compared to DI water. For HCl, 10mL of HCl changed buffer 1’s pH by about 3 whole units, and 9.5mL of HCl changed buffer 2’s pH by about 3 whole units as well. This means that our solutions were again much more resistant to the DI water than they were to the HCl. Both NaOH and HCl had much bigger impacts on our solutions than DI water did, even when they were given in much smaller amounts. Our solutions had a much harder time resisting changes from NaOH and HCl, and a much easier time resisting changes from DI water. 5. What is the difference between