Boiling in ethanol strips the leaf's waxy outer coating off, then the iodine turns it blue black because it's reacting to the presence of starch, a product of photosynthesis.
As we know PPM=mg/Kg, if d=1 so PPM=mg/L At first we must calculate the densty of ethanol in kg, so when we use 0.5L of ethanol it means : 0.789 kg/L = x kg/0.5L : x=0.394 Kg For a 100 ppm solution of iodine in 0.5 L of ethanol we have 100=mg I2 /0.394 kg so mg I2 = 39 mg S.Pourmand M.Sc. Organic chemistry
You think to iodine.
The leaf could not be simply dipped in iodine because it has a waxy cuticle layer that repels water, making it difficult for the iodine to penetrate through and properly stain the leaf for a starch test. To allow the iodine to effectively interact with the leaf and detect starch, the leaf needs to be boiled in alcohol to remove the waxy cuticle first.
Iodine crystals are not soluble in water. This is because Iodine crystals are non-polar. Water is a polar molecule and it therefore cannot attract an one of the iodine atoms since they have an electronegativity of zero.
Copper sulfate (white) or -sulfate-pentahydrate (blue) will dissolve in water, so C and I2 can be filtered off. Concentrate the blue solution by boiling off the water (evaporate) and cool down and crystallise (blue crystals of CuSO4(H2O)5 ). Iodine can be dissolved in ethanol 96% (tincturated) and Carbon is then filtered off. Evaporate ethanol at lowered pressure, but some I2 will also evaporate (purple vapor). The filtered C (carbon black) can be dryed off the filter paper, it is not soluble.
Iodine ion is not consumed; in the first step the iodine ion is oxidized to iodine, in the second step iodine is reduced to iodine ion.
You need to use iodine to see where the carbohydrates are stored. To make them visible, you must first boil the leaf in water, then boil it in ethanol or methanol.
Yes, it is safe to freeze a boiled ham joint without slicing it first.
It is important to properly dispose of expired iodine from your first aid kit.
Ethanol will vaporize at a lower temperature than water, so it will be collected first during the distillation process. Ethanol has a lower boiling point (78.37°C) compared to water (100°C), allowing it to evaporate and be collected before water.
Yes, ethanol can be separated from sand and water using distillation. Ethanol has a lower boiling point than water, so by heating the mixture, the ethanol will evaporate first and can be collected, leaving the sand and water behind.
First of all, it's just called 'Iodine," second, it's I2