Question

How do extensions of the Iodine Test for starch, like in the 'Iodine Clock Reaction,' typically yield results?

a. They provide qualitative data only.
b. They do not yield any results.
c. They yield quantitative results.
d. They are primarily used for pH testing.

Answer 1

Extensions of the Iodine Test, like in the Iodine Clock Reaction, provide quantitative results through titration. The transition from purple to colorless indicates the completion of the titration and the concentration of iodine or chlorine.

Step-by-step explanation:

The Iodine Clock Reaction is a chemical demonstration of a reaction with a sudden color change due to the starch-iodine complex formation. In the context of chlorine determination using iodine, the process involves an initial brown solution formation (I3) after adding potassium iodide (KI) and acid to a sample. It is then titrated with sodium thiosulfate (Na2S2O3) until the solution fades to pale yellow. Upon adding starch, a deep purple color forms, indicating the presence of I3. The endpoint of this titration is recognized by the sharp transition from purple to colorless, signifying completion.

Thus, the outcome of this process is a quantitative measurement, as the amount of titrant needed reflects the concentration of the substance being measured. The Iodine Test can detect the presence of starch in solution by a color change. This qualitative test is sensitive, and the vivid color change to a dark blue complex is indicative of starch's presence.