Week 8

TASK COMPLETED:

The following table shows the change in color in the veins when different solutions were injected into the veins after drying. As already mentioned, the leaf was exposed to heat and was squeezed to drain out the water from the veins to make it dry.
A solution of pH 4 was first injected into the veins and then a solution of pH 7 followed by 10 and 13 at a time. The veins were made to react for about 20 minutes with each solution. The white color of the veins disappeared (decolorized) gradually.

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The following table also shows the change in color in the veins when different solutions were injected into the veins after drying but the difference is that the veins were first made to react with bleach, a solution of pH 13. The veins of the leaf on the sides turned colorless with bleach and then as solutions of different pH (10, 7 and 4) were introduced, the color became more pre-dominant gradually. The surface of the leaf as expected turned green with bleach and slowly lost its color, with each process taking around 20 minutes.
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LESSONS LEARNT:

In table 1, we see that I started with a solution of pH 4 (weak acid) after exposing to heat or in other words, after removing a few water molecules. As mentioned earlier, the reason for the less probability of a color change could again be the less number of H+ ions in the solution. As solutions of increasing pH was used, the OH- ions started reacting with the already present H+ ions, thereby bringing about a decolorization (the white color on the sides became colorless).

In table 2, we see that bleach (pH 13) was used first. Being a strong alkali (base), given the fact that the water molecules were reduced by applying heat, the veins started turning colorless due to the further removal of H+ ions by bleach and the addition of OH- ions. Gradually as solutions of lower pH were introduced, the leaf turned acidic with more H3O+ ions and the colorless veins became more decipherable.

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