Question

Neutralization Reactions

In a clean, small container (glass vial or small paper cup), place about ten drops of an ammonia cleaner and two “squirts” of cabbage juice indicator.

Use a clean medicine dropper and count the number of drops of vinegar required to change the color of the solution from green to purple.

Repeat the above tasks with pickle juice or some solution that you found to have an acid pH slightly higher than vinegar.

Create a data table that summarizes your results of the two titrations.

Neutralization Reactions – comparison of two acid solutions neutralizing a base cabbage juice + ammonia solution

Insert Table Here

Drops of Ammonia	Vinegar	Pickle juice
10	6	8
10	7	7
10	6	8

In the titration of ammonia solution with vinegar, and with another acid solution with a slightly higher pH value, how did the amounts needed for the neutralization of the ammonia (signaled by the change from green to purple in the solution containing the ammonia and cabbage juice) compare? How does this comparison match the differences in pH values? What is the basis of any correlation between starting pH values of the two acids and amount required to neutralize the same amount of vinegar solution? Provide explanations for each for the three questions.

Answer 1

1) pH is defined as,

pH = -log[H⁺] or pH = log(1/[H⁺])

It means pH is the logarithm of RECIPROCAL of [H⁺] i.e. there is inverse proportion between pH and proton concentration [H⁺].

Lower the pH higher the [H⁺] and l higher the pH value lower is the [H⁺].

2) In Neutralization reaction H⁺ ions and here NH3 molecules combines to form NH4+ it means # of H+ ions determines Number of NH3 ions protonated.

In above mentioned Neutralization reaction experiment we chosen 2 acids of which one is vinegar (AcOH) and other with pH higher than vinegar i.e. other acid is less acidic as compared to other vinegar.

In other words if one take 10 drops of each vinegar acid and other acid, there will be large number of H+ ions in vinegar than other acid.

Hence same number of drops of NH3 will neutralize less number of vinegar acid drops and relatively more number of other acid drops.

WIth this explanation we get answer for all three questions

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