Week 7



The following table shows the change in color in the veins when different solutions were injected into the veins without drying. The latter part of the experiment involves exposing the leaf to heat to make it dry and squeezing out the water from the veins before injecting the solution. Since squeezing may cause the veins to collapse, I have also tried drying the leaf under the sun and the results are also tabulated.
A solution of pH 4 was first injected into the veins. There was a change in color from white to yellow. Gradually, the same part of the leaf was made to react with solutions of pH 7, 10 and 13 one by one, each for about 20 to 25 minutes. The vein gradually turned yellowish brown.

The following table also shows the change in color in the veins when different solutions were injected into the veins without drying but the difference is that the veins were first made to react with bleach of pH 13. This turned the surface of the leaf green making it prominent beginning from the sides. As solutions of pH 10, 7 and 4 were injected with time intervals of 20 to 25 minutes one by one, the sides turned colorless gradually.


In table 1, we see a change in color along the sides where the veins are exposed. The color change is basically at the sides because the solution was injected through the sides directly into the veins. The leaf was also peeled off in such a way that a part of the inner surface (viz. veins) was exposed. In other words, the upper surface of the leaf was peeled off to show better results. The reason for peeling off was to take a clearer look at the inside of the leaf, though there was no color change in the veins. Only the sides of the surface showed the change in color.

In table 2, we see that I started with bleach (ph 13). Since it is a strong base, the color change was decipherable. Although solutions of lower pH were added later on, the color change, back to normal (white along the sides) was not observed. They turned colorless instead due to the very few H3O+ ions formed by the solutions added. The reason could probably be the inability for most of the already formed H3O+ ions to change back to water molecules and hydrogen ions.

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