Question

Discussion Questions s Answer neatly and attach to cover sheet and all notebook pages and calculations. 1. Based on your observations while blowing into a beaker of water, write down a chemical reaction that explains the pH change. What is produced as a result of blowing into a container of water? How would this affect the pH of the solution? (0.5) 2. a. What is a buffer? Give a definition for a buffer. (0.5) In lab, you prepared 10 different solutions. Based on the definition of a buffer (not your experimental results), which solutions were considered buffers (list the solution numbers)? (0.5) Buffer Solutions a b, was solution #3 a buffer solution? Explain why or why not. (05) ntal results, which solution was the best at resisting pH change upon addition of largest buffer capacity)? How did you know this? Use your c. Based on your experime small amounts of H+ or OH-(i.e, which had the largest buffer capacity)? How did you know this? Use data to support your answer. (0.5) d. Explain how a buffer works to resist large pH changes. Provide enough information to indicate your understanding of buffers. (0.5)

Answer 1

2) a) A buffer is a solution that can resist pH change upon the addition of an acidic or basic components. It is able to neutralize small amounts of added acid or base, thus maintaining the pH of the solution relatively stable. This is important for processes and/or reactions which require specific and stable pH ranges.

A buffer is made by mixing a large volume of a weak acid orweak base together with its conjugate. A weak acid and its conjugate base can remain in solution without neutralizing each other. The same is true for a weak base and its conjugate acid.

Examples of buffer:

• Acetic acid (weak organic acid w/ formula CH₃COOH) and a salt containing its conjugate base, the acetate anion (CH₃COO^-), such as sodium acetate (CH₃COONa)
• Pyridine (weak base w/ formula C₅H₅N) and a salt containing its conjugate acid, the pyridinium cation (C₅H₅NH⁺), such as Pyridinium Chloride.
• Ammonia (weak base w/ formula NH₃) and a salt containing its conjugate acid, the ammonium cation, such as Ammonium Hydroxide (NH₄OH)