Question

How does ripper method work to determine $S{{O}_{2}}$ levels in wine?
What is the redox reaction occurring between $S{{O}_{2}}$ and ${{I}_{2}}$with the use of starch in the ripper method? How does this method chemically work to find the amount of free and total $S{{O}_{2}}$ in wine?

Answer 1

We know that the reaction proceeds, all available $S{{O}_{2}}$ will be consumed and the starch indicator added to the solution will bind with the unconsumed iodine, turning the solution black. The second step of the reaction requires pretreating with a solution with $NaOH~$ to release bound $S{{O}_{2}}$ The reaction with iodine can be done.

Complete step by step solution:
$S{{O}_{2}}$ in Winemaking: Winemakers add $S{{O}_{2}}$ to their product to keep it stable. Some of the $S{{O}_{2}}$ binds to the various compounds in the wine, as well as rest remains unbound the sum of the bound and free$S{{O}_{2}}$is the total $S{{O}_{2}}$. The Ripper method is titration technique for analyzing both the free and total $S{{O}_{2}}$ in wine.
Determination of free $S{{O}_{2}}$ : In titration, a standard solution of iodine reacts with the $S{{O}_{2}}$. $S{{O}_{2}}+{{I}_{2}}+2{{H}_{2}}O\to {{H}_{2}}S{{O}_{4}}+2HI$ At the equivalence point, the addition of one more drop of iodine solution causes the starch indicator to form a blue-black complex (you can also use an electrode to detect the equivalence point).
Determination of total $S{{O}_{2}}$
The method is the same as above except that you pretreat the sample with a solution of sodium hydroxide. The $NaOH~$ releases the bound $S{{O}_{2}}$ as the hydrogen sulfite ion. The sulfite ion is in equilibrium with the dissolved $S{{O}_{2}}$.$HSO_{3}^{-}\underset{{}}{\overset{{}}{\longleftrightarrow}}{{H}_{2}}S{{O}_{3}}\underset{{}}{\leftrightarrows}S{{O}_{2}}$

Note: Note that the free radicals derived from$S{{O}_{2}}$ in aqueous solution can cause ... in Brazil uses the Ripper method for the quantification of $S{{O}_{2}}$, which is based on the titration of sulfite with iodine in the presence of starch as sulphur dioxide $S{{O}_{2}}$has been used