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Chemical Analysis (Paper Chromatography (Calculating Rf value of each…
Chemical Analysis
Purity and formulations
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Formulations
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Each component in a formulation is in a measured quantity, and contributes to the properties so that it meets its required function
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Very important in pharmaceutical industry - eg. by altering formulation of a pill, chemists can make sure it delivers the drug to the correct part of the body at the right concentration, and that it's consumable and has a long enough shelf life
Formulations can be found in cleaning products, fuels, cosmetics, fertilisers, metal alloys and sometimes food and drink
Paper Chromatography
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During chromatography an equilibrium is formed between the two phases - they are constantly moving between the mobile and stationary phase
Mobile phase moves through the stationary phase, and anything dissolved in the mobile phase moves with it
How quickly a chemical moves depends on hit it's distributed between the two phrases - whether it spends more time in the stationary phase or the mobile phase
The chemicals that spend more time in the mobile phase than the stationary phase more further up the paper
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The components in the mixture normally separate through the stationary phase, if they all spent different amounts of time in the mobile phase
Number of spots my change in different solvents as distribution of the chemical will change depending on the solvent
Pure substance will only ever form one spot in any solvent as there is only one substance in the sample
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Test for anions
Carbonates
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If carbonate ions are present, the CO2 released will turn the limewater cloudy when it is bubbles through it
Test for sulphates
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Add few drops of dilute HCI with dropping pipette, followed by few drops of barium chloride solution
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Tests for cations
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Flame test procedure
Clean platinum wire loop by dipping it in dilute HCI, then hold it in blue flame from bunsen burner until it burns with no colour
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Only works for samples that contain a single metal ion - more than one gets a mixture of flames - some colours will be hidden by others
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