Distinction Level BTEC Applied Science Assignment C, Chromatography.

Distinction Level BTEC Applied Science Assignment C, Chromatography. Mixture : a mixture is made when two or more substance are combined , but they are not chemically bonded together Chromatography : a method used to separate chemical mixtures for analysis Soluble :solubility is the degree to which a substance dissolves in a solvent to make a solution Solvent : the substance in which a solute dissolved to produce a homogeneous mixture Mobile phase : the liquid that transports the substance mixture through the absorbing material which travels along the stationary phase and carries the substance components with it Stationary phase : the solid material that absorbs the mixture flowing through it Adsorption : the process by which atoms, molecule or ions from a gas or liquid adhere to a surface the process is not permitted Chromatogram : the resulting paper or plate produced showing the substance Immiscible: liquids that do not mix together Porosity : a measure of the volume of tiny holes in a material divided by the total volume of the material measuring rf values When the solvent front reaches the top of the TLC plate or chromatography paper, it is measured to determine how far it has travelled. We can tell how far the solution has moved and how far the spots have migrated by calculating the rf. Draw a line from the solvent front to the original line and measure it with a ruler to see how far the solvent has travelled. Then draw a line from the middle of the spot to the original line and measure it again with a ruler. This would display how far the spot has travelled. This equation may be used to calculate the rf value. rf= distance travelled by substance/ distance travelled by solvent font Polarity Thin layer chromatography produces more usable chromatograms than paper chromatography because it shows more separation of the components in the mixture, making analysis easier. The distance travelled by the sample is determined by the size of the molecules. Larger molecules require more time to migrate up the TLC plate or chromatography paper, whereas smaller molecules are more mobile. The solvent you choose influences how far the spot travels in the same way that the polarity of the molecule affects how far the spot travels. Polar molecules are more attracted to polar solvents and so travel further if a polar solvent is used instead of a non-polar solvent. paper chromatography of plant pigments I conducted a practical to investigate the techniques and separation methods used in paper chromatography to detect the pigment in spinach leaves aim: Using paper chromatography to identify the pigments in spinach leaves Pigments may be split into different colour bands using paper chromatography. Chromatography is the separation of a mixture into its elements. Separation occurs by absorption, and capillarity pushes the mixture up the paper at various speeds. On the paper, the pigments separate and appear as coloured streaks. The pattern of separated components is referred to as a chromatogram. cautions o avoid poisonous or expired plants o make sure to organise the leaf by type e.g. sample of spinach leafs , sample of maple leafs o for a higher concentrated solution find the grana and chloroplast of the plant o chromatography solvent like propane are flammable , make sure that no flames are open as this can lead to a hazard o make sure to do the chromatography in a well ventilated room as this would avoid inhalation of the fumes equipment needed in paper chromatography o safety goggles o chromatography solvent ( propane ) o chromatography paper or filter cut into rectangle strips . 1cm x 15cm o fresh spinach o chromatography chamber o capillary tube o pencil and ruler o paper clip or tape o mortar and pestle o sand procedure for a paper chromatography