wk3 session 2 tutor presentation

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Effective from September 2015 | Plus Term Chemistry week 2 session 2

As a group: describe what happened to the cars between the beginning and end of the drag race.I will be looking for the best use of keywords that we can apply scientifically


PLACE YOUR BETS!321GO


Who won and why?

1st2nd3rd4th5th


Discuss: What problems might you have if you were sharing these with friends?

Mixtures


What is a mixture? a mixture contains different chemical elements or compounds that share the same space but are not chemically bonded to each other


Write the letters of the boxes that contain mixtures.

NaClNaClNaClNaClClNaClClNaClOHCHHHHHCHHHHNNOOCOOCONNOCOOHHCHHHHCCHHHHABCDEFGH


Case StudyHannah the Chemist has found a plant in the amazon rainforest that shows evidence of curing the flu


Case StudyHannah extracts an oil from the plant and tests it on volunteers


Case StudyThe volunteers flu symptoms are improved, but they all get diarrhoea


Case StudyIn groups, propose why Hannah the Chemists plant oil has two effects, and what are these effects?Suggest what she needs to do to resolve the issue.(Think back to our starter)


Did you make these points?Hannahs plant oil extract contains a mixture of compounds.One of these compounds cures the flu.The other compound causes diarrhoea.Hannah should attempt to separate the compounds in her oil.This separation technique is a bit like a race, only with compounds instead of cars.11112Mark your group /6


What is this separation technique called?Use your devices to find out the name of a separation technique in chemistry.

The word starts with a C

Write it on scrap and hand it to me when you think you have the answer.


Chromatography!Tuesday, 13 October 2015

ChromatographyC/WI think chromatography is:Task: Describe in your own words, what you think chromatography is:


Have you seen this before, what is a solvent?


SolventA solvent is a substance that dissolves something.In your books, list examples of solvents you can think of:

Tuesday, 13 October 2015

ChromatographyC/WA solvent is:

Solvents I know are:


Solvent examples:Salt dissolves in water, so what is the solvent?

Water! - H2O


Solvent examples:Nail varnish dissolves in Acetone (Nail varnish remover), so what is the solvent?

Acetone!


Solvent demonstrationPolystyrene dissolving in acetone!Tights dissolving in sulfuric acid!


So a solvent is:And a solute is:And a solute dissolved in a solvent makes a:A substance that can dissolve somethingThe thing that is dissolved by the solventSolution


So how does this relate to chromatography?We have to dissolve the substance we want to separate to make a solution.


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Preparing the Chromatography StripsCollect one experiment tray per tableIn pairs draw a line 2 cm above the bottom edge of the strip with a pencil and rulerWrite 5 crosses approximately 1.5cm apart so that they are evenly spacedDip a capillary tube into one of the food dyes and put a small spot on the cross. Repeat this for the other food dye solutions.


Tasks:1. Draw and label a diagram of paper chromatography (Use the keywords)

2. Explain how we can use chromatography to identify if certain known compounds are present in our mixture.

3. Propose how Hannah could use paper chromatography, to separate and identify her flu/diarrhoea compounds.Keywords C - Chromatography, Separation, Compounds, B - Solvent, Solute, Solution,A-A* Mobile Phase, Stationary Phase, Solvent Front, Baseline, Reference Compound.


Chromatography key wordsSolvent a chemical such as water that dissolves another chemicalSolute a chemical that is dissolvedSolution a mixture of a solvent and soluteDifferential showing a difference, distinctiveAffinity natural attraction or force between thingsMobile Phase gas or liquid that carries the componentStationary Phase the part of the apparatus that does not move with the sample


Retention factor (Rf) valuesThe Rf factor is used to compare the components of various samples. The Rf values of suspect samples can be compared with known samples.

Rf = distance from the base line to the spot distance from the base line to the solvent frontSolvent frontthe point at which the water stopped moving up the paperCentre of spotthe point at which a band or spot of colour is Base linethe line where the original sample was placedIf two substances have the same Rf value, they are likely (but not necessarily) the same compound. If they have different Rf values, they are definitely different compounds.


Developing the ChromatogramsPour a little water in the beaker to 1 cm depthPlace the strips in the beakers. Make sure the water solvent does not come above your start line.You may use a paper clip to attach the top of the chromatogram to the glassLet strips develop for around 15 minutes so that the mobile phase (solvent + dye) has moved over half way up the stationary phase (paper).Remove the strips and allow them to carefully dry them (takes 1 minute).


Exam Practice


Exam Practice


Exam Practice


Exam Practice


wk3 session 2 tutor presentation

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