Combustion in the Magnesia Channel 5

Contents:

Analysis overview...... 3 Preliminary Tests...... 4 Colour...... 4 pH-value...... 4 Conductivity...... 4 Density...... 5 Flame test...... 5 Combustion in the magnesia channel...... 5 Qualitative Analysis...... 6 Glucose analysis – Fehling’s Reaction...... 6 Fructose analysis – Seliwanow’s Reaction...... 6 Saccharose analysis...... 6 Analysis on Vitamin C - Tillmann’s Reaction...... 7 Phosphate...... 7 Chloride...... 8 Sodium und Potassium...... 8 Quantitative und semi - quantitative Analysis...... 9 Ca2+/Mg2+- Analysis by using EDTA...... 9 Analysis on the total content of acid (using the pH-meter)...... 9 Analysis on the total acid content in colourless drinks (using phenolphthalein)...... 10 Analysis on Phosphoric acid in Cola (using the Conductometer)...... 10 Analysis on total sugar content in colourless drinks (using the Refractometer)...... 11 Extras...... 12 Decolourization...... 12 Caffeine (Thin Layer Chromatography):...... 12 Quinine (Fluorescence)...... 13 Taurine – Ninhydrin Reaction...... 13 Aspartame – Ninhydrin Reaction...... 13 Dyestuff (Thin Layer Chromatography)...... 14 DRINKS IN PROJECT experimental part

Analysis overview Analysis Method Additional info Amounts Recycling Preliminary Tests pH-meter, universal Some pH-value indicator (paper and → Acid content (acidity) drops up no liquid) to 5 mL Conductometer by Conductivity → Ions (acids, salts, ...) ~ 20 mL yes WTW Colour Observation, Eyes → Additional substances yes Density Areometer → Sugar content 50 mL yes Flame test Gas burner, Eyes → Cations Drops no Combustion in Gas burner → Sugar content < 1 mL no magnesia channel Qualitative Glucose Fehling reaction ~ 2 mL no Fructose Seliwanow reaction Resorcin ~ 2 mL no Monosaccharide after Saccharose → Total sugar ~ 2 mL no cleavage Ascorbic acid Tillman reaction Vitamin C destruction ~ 2 mL no Phosphate Precipitation reaction Ammonium molybdate ~ 2 mL no Chloride Precipitation reaction Silver nitrate ~ 2 mL no Sodium Flame test Spectrometer Drops no Potassium Flame test Spectrometer Drops no Quantitative und semi-quantitative Magnesium und Complex metric titration Digital burette 100 mL no Calcium Titration by conductivity, → CO2 (carbonic acid) - Total acid pH-value (pH-meter, 10 mL no content? indicator) Total sugar Refraction index Refractometer Drops no Extras Thin layer Caffeine Drops no chromatography (TC) Quinine UV-lamp ~ 2 mL no Taurine Ninhydrin ~ 2 mL no Thin layer Dye stuffs Drops no chromatography (TC) Aspartame Ninhydrin after cleavage ~ 2 mL no

A. Hofer, E. Klemm, I. Trimmel November 2006 3 DRINKS IN PROJECT experimental part

Preliminary Tests For the analysis the drinks have to be opened for a certain time. Think of reasons why this has to be done. What results would otherwise be found? Reflect on this topic in each experiment!

Colour Try to give a detailed description of your observation. pH-value

Equipment: Materials: pH - meter, beaker 50 mL, glass rod, liquid universal indicator, indicator paper test tube, test tube rack

Procedure and Observation: Measure the pH-value of the drink. Pay attention to the drink’s colour. Decide on your own for the most suitable measuring method. Take a liquid universal indicator, an indicator paper or pH-Meter.

Conclusions and Questions: Which method did you choose? Explain the reasons for your decision? What’s the result of your measurement?

Conductivity

Equipment: Materials: Conductometer by WTW, Deionised water beaker 50 mL

Procedure and Observation: Take a glass which is deep enough to work with the conductometer, but minimizes the wastage of the drink. Don’t stir while measuring! Note the corresponding value.

Conclusions and Questions: What’s the result of your measurement?

Density

Equipment: Materials: Areometer, measuring cylinder

Procedure and Observation: Pour 50 mL of your drink into a measuring cylinder. Put the areometer into the cylinder and note the corresponding value.

Conclusions and Questions: What’s the result of your measurement?

Flame test

Equipment: Materials: Gas burner, magnesia rod, watch glass, crucible tongs, cobalt glass

Procedure and Observation: Put a few drops of your drink onto the watch glass. Hold the magnesia rod with crucible tongs into the hottest spot of the burner’s flame (where is this spot?) until it glows and the flame looses it’s colouring. Dip the rod into your drink and afterwards hold it in the burner’s flame again. Don’t forget to take a look through the cobalt glass. Observe the colouring of the flame.

Conclusions and Questions: What’s the result of your observation?

Combustion in the magnesia channel

Equipment: Materials: Gas burner, magnesia channel, crucible tongs

Procedure and Observation: Put some drops of your drink onto the magnesia channel. Hold it by using crucible tongs into the hottest spot of the burner’s flame (where is it?). Wait until the whole liquid is combusted, evaporated, … . Make an exact observation of the whole procedure.

Qualitative Analysis Glucose analysis – Fehling’s Reaction

Equipment: Materials: Test tube rack, test tubes, heater, water Fehling I und Fehling II solutions, solution bath (water filled big beaker) of glucose

Procedure and Observation: Prepare in at least 2 test tubes a mixture of 1 mL Fehling I and 1 mL of Fehling II solution. Afterwards add about 2 mL of the glucose solution to one of them and about 2 mL of your drink to the other. Heat the tubes in the water bath. Observe!

Hint: In crystal sugar (saccharose) Glucose is bonded in the molecule, which effects that you can’t proof it with this method. To do this, look at the saccharose analysis for further information.

Fructose analysis – Seliwanow’s Reaction

Equipment: Materials: test tubes, test tube rack, water bath, Resorcin, concentrated hydrochloric acid, heater, safety goggles solution of fructose

Procedure and Observation: Take 1 mL hydrochloric acid and add a few drops of resorcin solution. Prepare 3 test tubes and fill one of them with 2 mL of your drink, another one with 2 mL water and the last one with 2 mL of fructose solution. Put the tubes into the boiling water bath and heat them for 1 to 2 minutes. Compare the new colour to it’s original.

Conclusion and Questions: What’s the result of your experiment?

Saccharose analysis

Equipment: Materials: Test tube rack, test tubes, beaker, Solution of saccharose, diluted sodium lye heater, water bath (water filled big (NaOH), concentrated hydrochloric acid (HCl), beaker), safety goggles indicator paper

Hint: Saccharose is a compound of one molecule of glucose and fructose, which has to be hydrolysed (cleaved) by acid. Afterwards the compounds (glucose and fructose) can be separately analysed.

Procedure and Observation: Mix your drink with a few drops of hydrochloric acid in a beaker. Put the beaker onto the heater and boil the mixture for a few minutes. After cooling down the solution add sodium lye until the pH-value signalises alkaline. Check this by using indicator paper (why do you take paper?). Now you can prove the single components of saccharose. Choose the analysis which caused a negative result in the former experiments to prove the isolated saccharose content. If both former experiments caused positive results then you can only test the total sugar content.

Conclusions and Questions: What was your procedure? Give a detailed documentation of your work, thoughts and observations!

Analysis on Vitamin C - Tillmann’s Reaction

Equipment: Materials: Test tubes, test tube rack DCPIP solution, Vitamin C (Ascorbic acid) solution

Procedure and Observation: Prepare in one test tube 2 mL drink and in a second one 2 mL ascorbic acid solution. Add the DCPIP solution drop by drop. Stop your procedure when there is no more decolouration visible.

Hint: The colour depends on the pH-value of the solution. It can be blue or pink.

Conclusions and Questions: What’s the result of your observation? Why can’t an analysis on the amount of vitamin C in opened drinks be done?

Phosphate

Equipment: Materials:

Test tubes, test tube rack, Ammonium molybdate, diluted nitric acid (HNO3) water bath (water filled big beaker)

Procedure and Observation: Prepare a few mL of your drink in a test tube and add 1 mL nitric acid. Adding ammonium molybdate precipitates a yellow coloured deposit (ammonium molybdophosphate). If there is no visible reaction then heat up your test tube in a water bath.

Conclusions and Questions: Why is this an analysis on phosphate? What are the results of your observations?

Chloride

Equipment: Materials:

Test tubes, test tube rack Silver nitrate (AgNO3)

Procedure and Observation: Prepare a few mL of your drink in a test tube. Adding silver nitrate precipitates a white coloured deposit (silver chloride).

Conclusions and Questions: Why is this an analysis on chloride? What are the results of your observations?

Sodium und Potassium

Equipment: Materials: Gas burner, magnesia rod, watch glass, crucible tongs, spectrometer

Procedure and Observation: Put a few drops of your drink onto the watch glass. Hold the magnesia rod with crucible tongs into the hottest spot of the burners flame (where is this spot?) until it glows and the flame looses it’s colouring. Dip the rod into your drink and hold it afterwards again into the burner’s flame. Observe the colouring of the flame by using the spectrometer (for further information use the instruction manual).

Conclusions and Questions: What’s the result of your observations?

Quantitative und semi - quantitative Analysis Ca 2+ /Mg 2+ - Analysis by using EDTA

Equipment: Materials: Erlenmeyer flask, digital burette, Indicator buffer-tablet, EDTA solution (c = 0,1 measuring flask (50 mL), magnetic mol/L), Ammonia solution 25 % stirrer, magnetic bone, plastic pipette, safety goggles

Procedure and Observation: Pour exactly 50 mL of your drink into the Erlenmeyer flask and fill it up with distilled water to about 100 mL. Use this liquid to dissolve one indicator buffer tablet while stirring. Add about 1 mL ammonia solution (fume cupboard and safety goggles!!!). Titrate by adding EDTA solution and observe the colours from red over grey to green. Stop when it turns to green. Stir constantly during the whole procedure. Note the usage of EDTA solution.

Conclusions and Questions: Calculate the concentration of magnesium and calcium ions.

Hint: One mole EDTA reacts with one mole magnesium or calcium. Give the result in mg per 100 mL.

Analysis on the total content of acid (using the pH-meter)

Equipment: Materials: burette, beaker (50 / 100 mL), Sodium lye (NaOH 0,1M) pipette (10 mL), pH-meter, magnetic stirrer, magnetic bone

Procedure and Observation: Pipette 10 mL of your drink in a beaker. Dip the electrode into the liquid. Add NaOH solution mL-wise through the burette until there’s no more change in the measured pH-value. Stir during the whole procedure. Keep the electrode away from the magnetic bone! Note the usage of NaOH and the pH-values in mL.

Conclusions and Questions: Design a diagram (ordinate pH-value, abscissa mL lye) using your notes. The inflexion point is the end point of the titration. (Find out the amount of NaOH at this point.) Calculate the citric acid content of your drink. Give the result in mol/L, g/L and g/100 mL.

Three moles NaOH react with one mole citric acid (C6O7H8) (biggest amount of the total acid content).

Analysis on the total acid content in colourless drinks (using phenolphthalein)

Equipment: Materials: burette, beaker (50 / 100 mL), indicator (phenolphtalein), Sodium lye (NaOH 0,1M) pipette (10 mL), magnetic stirrer, magnetic bone

Procedure and Observation: Pipette 10 mL of your drink in a beaker. Add a few drops of indicator. Afterwards add NaOH solution mL by mL through the burette until there’s a colour change from colourless to pink. Stir during the whole procedure. Note the usage of NaOH at the end point.

Conclusions and Questions: Calculate the citric acid content of your drink. Give the result in mol/L, g/L and g/100 mL.

Three moles NaOH react with one mole citric acid (C6O7H8) (biggest amount of the total acid content).

Analysis on Phosphoric acid in Cola (using the Conductometer)

Equipment: Materials: burette, beaker (200 mL), measuring Sodium lye (NaOH 0,1M) flask (100 mL), conductometer, magnetic stirrer, magnetic bone

Procedure and Observation: Pour exactly 100 mL of your drink into a beaker. Dip the electrode into the liquid. Add NaOH solution mL by mL through the burette. Stop titrating when the conductivity values have passed the turning point (end point) and have been increasing again for a while. Stir during the whole procedure. Keep the electrode away from the magnetic bone! Note the usage of NaOH and the conductivity-values in mL.

Conclusions and Questions: Design a diagram (ordinate conductivity-value, abscissa mL lye) using your notes. The function’s minimum is the end point of the titration. (Find out the amount of NaOH at this point.)

Calculate the phosphoric acid content of your drink. Give the result in mol/L, g/L and g/100 mL.

One mole NaOH reacts with one mole phosphoric acid (H3PO4).

Analysis on total sugar content in colourless drinks (using the Refractometer)

Equipment: Materials: Refractometer HRO 32 von Krüss Sugar solution

Procedure and Observation: First of all eliminate the whole gas by stirring. (Why?) Before you use the refractometer read the instruction manual.

Hint: Measured values are the mass percentage of sugar in your drink.

Conclusions and Questions: What did you observe? What are advantages or disadvantages using the refractometer?

Extras Decolourization

Equipment: Materials: beaker, Erlenmeyer flask, funnel, activated carbon or magnesium oxide filter paper

Procedure and Observation: Decide how much decoloured drink you need for further experiments. Then pour this amount into the beaker. Add one spatula activated carbon or magnesium oxide and mix it with your drink. Filtrate the mix (twice).

Hint: Activated carbon or magnesium oxide is able to decolour solutions, because it adsorbs dyestuffs (takes it out of the solution).

Caffeine (Thin Layer Chromatography):

Equipment: Materials: silica gel TLC sheets, TLC-box (glass with solvent (19:1 dichloromethane: methanol), cover), UV (ultraviolet)-lamp solution of caffeine (Merck) in dichloromethane for comparison;

Procedure and Observation: Mix dichloromethane and methanol in a ratio of 19:1 (=solvent) and dissolve the pure caffeine in dichloromethane. Pour a little bit of solvent into the TLC-box to saturate it with solvent vapour. (Don’t forget the cover!) Draw a start line on the silica gel sheet (0,7 cm distance from the border). (Attention! Use a soft pencil and do not destroy the silica gel coat!) Mark two spots on your start line. Choose an approximate distance of 2 cm. (Spots to apply the samples.) Now take a capillary and fill it with your decoloured drink. Hold the capillary vertically and touch (don’t destroy the silica gel coat) one of your marked spot. The capillary empties on it’s own. Repeat the last steps with the caffeine solution. Put it onto the second marked spot. Wait until both spots are completely dried. Afterwards put the TLC sheet (start line on the bottom) into the TLC-box filled with solvent. (Attention! The solvent surface has to be under your start line.) Cover the TLC-box and wait for about 15 minutes. Until the solvent raised up to approximately 6 cm. (Attention! Stop before the solvent front reaches the border on the top.) Draw a second line immediate after taking the sheet out of the solvent.

During the procedure the solvent takes along the caffeine. You can detect two spots between the two lines. By the reason that these spots are colourless you have to make them visible with the UV-lamp. If there is any caffeine in your drink the spots are nearly on the same level.

Conclusions and Questions: How did you work? Where did you have troubles? What’s most important to be aware of? Take an outline of your result seen on the TLC sheet in your notes.

Quinine (Fluorescence)

Equipment: Materials: UV (ultraviolet)-lamp, test tubes quinine solution

Procedure and Observation: Fill one test tube with water, one with your drink and one with quinine solution. Irradiate the test tubes in a shaded room with the UV-lamp (wavelength ~366 nm; Attention! UV-waves are harmful for human eyes!)

Conclusions and Questions: What did you observe?

Taurine – Ninhydrin Reaction

Equipment: Materials: test tubes, test tube rack, water bath taurine solution, alcoholic ninhydrin solution

Procedure and Observation: Fill one test tube with your drink, one with the taurine solution and one with water. Add to every test tube a few drops of the alcoholic ninhydrin solution and heat it up in a water bath.

Hint: A positive reaction causes a blue-violet colouring. Attention! The reaction between aspartame and ninhydrin causes a colouring (lilac).

Aspartame – Ninhydrin Reaction

Equipment: Materials: test tubes, gas burner aspartame solution, alcoholic ninhydrin solution

Procedure and Observation: Fill one test tube with a few mL of your drink and two with aspartame solution. Boil the liquid in the test tubes for about one minute using the burners flame. (Attention! Use boiling stones or shake the tubes while boiling!). Don’t boil one of the test tubes with aspartame solution for comparison! Add a few drops of ninhydrin solution to every single test tube.

Dyestuff (Thin Layer Chromatography)

Equipment: Materials: silica gel TLC sheets, TLC-box (beaker Solvent (20:5:3 sodium citrate solution : with cover), UV (ultraviolet)-lamp ammonia solution : methanol), reference solutions

Procedure and Observation: Pour a little bit of solvent into the TLC-box to saturate it with solvent vapour. (Don’t forget the cover!) Draw a start line on the silica gel sheet (0,7 cm distance from the border). (Attention! Use a soft pencil and do not destroy the silica gel coat!) Mark two (max. three) spots on your start line. Choose an approximate distance of 2 cm. (Points to apply the samples.) Now take a capillary and fill it with your drink. Hold the capillary vertically and touch (don’t destroy the silica gel coat) one of your marked spots. The capillary empties on it’s own. Repeat the last steps with the reference solution. Put it onto the second marked spot. Wait until both spots are completely dried. Afterwards put the TLC sheet (start line on the bottom) into the TLC-box filled with solvent. (Attention! The solvent surface has to be under your start line.) Cover the TLC-box and wait for about 20 minutes, until the solvent raised up to approximately 6 cm. (Attention! Stop before the solvent front reaches the border on the top.) Draw a second line immediate after take the sheet out of the solvent. During the procedure the solvent takes along the dyestuffs.

Conclusions and Questions: How did you work? Where did you have troubles? What’s most important to be aware of? Take an outline of your result seen on the TLC sheet in your notes.

A. Hofer, E. Klemm, I. Trimmel November 2006 14