What happens when you add iodine to orange juice?

Adding iodine to orange juice causes a chemical reaction that results in a noticeable color change. The reaction involves the interaction between iodine and vitamin C (ascorbic acid) present in the orange juice.

When iodine is added to orange juice, the vitamin C acts as a reducing agent and reacts with the iodine to form ascorbic acid dehydroascorbic acid. This reaction results in the loss of electrons from vitamin C, leading to a chemical reduction of iodine.

The reduced form of iodine, known as iodide ions (I-), combines with hydrogen ions (H+) to produce hydrogen iodide (HI). Hydrogen iodide is an unstable compound prone to oxidation in the presence of atmospheric oxygen.

The oxidation of hydrogen iodide leads to the formation of iodine molecules (I2) and water (H2O). These iodine molecules are responsible for the observed color change in the orange juice.

Initially, the orange juice may turn a dark blue or black color due to the formation of a temporary complex between iodine and starch molecules naturally present in the orange juice. However, this dark color quickly disappears as the reaction progresses, and the orange juice takes on a pale, yellowish-brown hue.

The color change from dark blue or black to pale yellowish-brown indicates the consumption of vitamin C and the subsequent formation of iodine molecules. The exact shade of yellowish-brown may vary depending on the concentration of vitamin C in the orange juice and the amount of iodine added.

This reaction serves as a simple and visual demonstration of the reducing properties of vitamin C and the presence of starch in orange juice. It showcases a basic chemical interaction between a vitamin (ascorbic acid) and a common element (iodine).