Question

Saline solution, iced tea and mouthwash all had buffering ability. I need help with question 5 and 6.

PARTS 2/3: DATA ANALYSIS AND QUESTIONS 1. Show the calculations you used to transform your data into a meaningful set of numbers. 2. Order the 4 solutions from best to least ability to buffer against acid. Explain your choice. 3. Order the 4 solutions from best to least ability to buffer against base. Explain your choice. 4. Which of the test solution(s) behave as buffers? Which solution(s) do not? Explain. 5. What specific purpose does a buffer serve for each of the solutions which were found to have buffering ability? (i.e. why do those solutions contain buffers?) 6. Answer this question for each solution found to have buffering ability. Knowing how a buffer is composed, which of the substances on the list of ingredients might act as a buffer? Explain. An ingredient list may be found on the product in the lab or by searching for the exact same product online (and referencing).

Answer 1

The pH of a buffer solution doesn't change with slight additions of acid or base. This reason can be used to explain questions 5.

Saline solution is used to clean wounds and thus should not react with any acid/base near the wound such that it causes us some harm.
Similarly Iced tea and mouthwash are in contact with our internal body organs and should not change their pH by reacting with any chemical species inside our body.

Any buffer is made with the combination of a weak acid and its salt or a weak base and its salt.
Saline solution - Acidic buffer - due to CO2 and water
Iced tea - Acidic buffer - Phosphoric acid and sodiumhexametaphosphate
Mouthwash - Acidic buffer - Benzoic acid and methyl salicylate