Put 20ml of sodium hydroxide in a cup. Measure the mass of the sodium hydroxide. Find the density of each liquid by dividing how many grams it is by 20ml. Compare the differences between the 2 liquids. Conclusion In conclusion, when 20ml of methylene blue was added to 20ml of sodium hydroxide the combined liquid in the flask turned blue and moderately transparent. After shaking the flask and letting it sit the liquid in t he flask slowly became clear and a blue ring formed along the edge of the flask at the surface of the liquid. Blue bottle reaction video, the blue bottle experiment is a chemical reaction.
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The activation energy can be calculated using a normal Arrhenius plot - natural logarithm of the decolouration time (ln t ) against the reciprocal of absolute temperature (1/ T ). Campbell 2 explains this can be done bullet because the rate of the slow step is independent of the oxygen concentration, and thus the time, t, which is required for the total oxygen to disappear, is directly related to the rate constant,. A straight line is obtained from the plot of ln t against 1/. The rate law for the reaction is: 3 Rate k doxchoh- where dox is the oxidised ( blue ) form of methylene blue and ch is the carbohydrate, glucose. A simple mechanism for the reaction is: ch oh- C- H2O O2 D Dox (Fast) Dox C- d x- (Slow) where d is the reduced (colourless) form of methylene blue and x- represents the oxidation products from glucose (arabinoic, formic, oxalic and erythronic acids). The enthalpy of the reaction has been reported as 23 kj mol-1. Transcript of, blue, bottle, experiment, the, blue, bottle, experiment, by, joel McGarrity, and Melissa pede The purpose Of The. Experiment The purpose of this experiment is to figure out why methylene blue turns clear and rises when added homework to sodium hydroxide The liquid is expected to change color because the sodium hydroxide is thinner than the methylene blue and the methylene blue acts like. The hypothesis The materials The materials that were used were - 1 beaker - safety goggles - 1 dropper - lab coat - methylene blue - sodium hydroxide - 1 scale - waste bin The Procedure. Put 20ml of methylene blue in a cup. Measure the mass of the methylene blue.
Dissolve.5 g of sodium hydroxide in flask a and 5 g of sodium hydroxide. Add 1 cm3.2 per cent solution of methylene blue into each flask, stopper both flasks and shake to life dissolve the indicator. Set aside the flasks and observe as the blue colour gradually disappears at a different rate in each flask. The flask with the higher concentration takes about half the time for the colour to disappear, using up the dissolved oxygen twice as fast. You should point out to students that, having gone colourless, a blue zone remains close to the surface of the solution. This is a result of oxygen diffusing from the air space within the flask into the solution. Teaching goals This experiment could be used to determine the kinetics of the reaction and thus the mechanism. The reaction is first order with respect to the hydroxide ion, methylene blue and glucose but zero-order with respect to oxygen. The rate law can be found by measuring how long it takes for a solution of known concentration to go colourless.
If the flask is shaken a few times, then the blue colour is restored. This cycle of colour change can be repeated many times over a period of 45 minutes. Safety, sodium hydroxide is corrosive, contact with the eyes can cause serious, long-term fruit damage. Significant heat is released when sodium hydroxide dissolves in water. Special tips, several variations on this demonstration are possible, one of which allows students to see the effect of concentration on the rate of reaction. Half fill two one-litre conical flasks with distilled water. Put.5 g of glucose into one flask (A) and 5 g of glucose into the other (B).
The ' blue bottle ' reaction 1, glucose (an aldohexose) in an alkaline solution is slowly oxidised by oxygen, forming gluconic acid: CH2OH-(choh)4-cho o2 CH2OH-(choh)4-CO2h, in the presence of sodium hydroxide, gluconic acid is converted to sodium gluconate. Methylene blue speeds up the reaction by acting as an oxygen transfer agent. As glucose is oxidised by the dissolved oxygen, methylene blue itself is reduced, forming the colourless methylene white, and the blue colour of the solution disappears. Kit 6 g sodium hydroxide, naoh; 10 g glucose, c6H12O6; 300 cm3 distilled water;.2 per cent methylene blue indicator solution; one-litre conical flask; rubber stopper for flask. Procedure, put the water in the flask, add and dissolve the sodium hydroxide. Add the glucose when the sodium hydroxide has dissolved. When all the glucose has dissolved, add five drops of the indicator solution and swirl. Allow to stand and the blue colour in the flask slowly disappears forming a colourless solution.
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This goes from pale blue to a beautiful purple-pink colour on shaking and reverses on standing. On first adding the dye, the solution is dark blue. This fades after about one minute. Mixtures of the above dyes can also be used. Health safety checked, 2016 report This Practical Chemistry resource was developed by the nuffield foundation and the royal Society of Chemistry. nuffield foundation and the royal Society of Chemistry weblinks wikipedia - redox indicator Page last updated October 2015.
Methylene blue is an aromatic compound that produces a blue solution when dissolved in water. It is a redox indicator and relies on electron transfer rather than changes in hydrogen ion concentration to change colour. A redox indicator undergoes a definite colour change at a specific electrode potential. A number of features of the ' blue bottle ' reaction makes it ideal to use for investigating reaction kinetics - it is very quick, the chemicals are relatively cheap and safe, and the measurements are straightforward. In this demonstration, a stoppered flask is half-filled with a colourless solution. On shaking, the solution turns blue, and on standing, the solution returns to colourless. This cyclic colour change can be repeated by successive shaking and standing.
If visitors are to be allowed to shake the bottle themselves it might be wise to use a plastic screw-top pop bottle to eliminate the risk of the stopper coming off or the bottle being dropped and broken. The solution does not appear to interact with the plastic over a period of a day but it would be sensible to try out the bottle you intend to use beforehand. Redox indicators other than methylene blue can be used to present other colours and make the demonstration really striking. In each case add the stated amount of indicator to the basic recipe of 10 g of glucose and 8 g of potassium hydroxide in 300 cm3 of water. 1, phenosafranine, this is red when oxidised and colourless when reduced. Use about 6 drops of.2 solution in water for a bottle that goes pink on shaking and colourless on standing.
The initial pink colour takes some time to turn colourless at first. A mixture of phenosafranine (6 drops) and methylene blue (about 20 drops of the.1 solution in ethanol) gives a bottle which will turn pink on gentle shaking through purple with more shaking and eventually blue. It will reverse the sequence on standing. 2 Indigo carmine Use 4 cm3 of a 1 solution in water. The mixture will turn from yellow to red-brown with gentle shaking and to pale green with more vigorous shaking. The changes reverse on standing. These colours are those of traffic lights. 3 Resazurin (irritant - see cleapss hazcard) Use about 4 drops of a 1 solution in water.
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Shaking the solution admits oxygen, which re-oxidises the methylene blue back to the blue form. To confirm that oxygen is hotel responsible for the colour change, nitrogen can be bubbled through the solution for a couple of minutes to displace air from the solution and the flask. If the stopper is now replaced and the bottle shaken, no colour change will occur. Reintroducing the air by pouring the solution into another flask and shaking will restore the system. Natural gas can be used (in a fume cupboard) if nitrogen is not available. Some teachers may wish to present this experiment as a magic trick. The colour change can be brought about by simply pouring the solution from a sufficient height into a large beaker. This experiment can be a popular Open day activity.
B The colour will change to blue and will fade back to colourless over about 30 seconds. C The more shaking, the longer the blue colour will take to fade. D The process can be repeated for over 20 cycles. E After some hours, the solution will turn yellow and the colour changes will fail to occur. Teaching notes, a white keywords background helps to make the colour changes more vivid. A white laboratory coat is ideal. On a cold day it may be necessary to warm the solution to at least 20 c, otherwise the changes are very slow. Methylene blue is a redox indicator and is colourless under reducing conditions but regains its blue colour when oxidised. The removal of the blue colour is caused by the glucose which, under alkaline conditions, is reducing the methylene blue to a colourless form.
hydroxide into the 1 dm3 conical flask. C Add 300 cm3 of water and 10 g of glucose and swirl until the solids are dissolved. D Add 5 cm3 of the methylene blue solution. The exact quantity used is not critical. E The resulting blue solution will turn colourless after about one minute. Stopper the flask and label it irritant (due to the potassium hydroxide present). The demonstration a Holding the stopper securely in place, shake the flask vigorously so that air dissolves in the solution.
Glucose (dextrose 10 g, methylene blue (harmful.05 g, ethanol (ida industrial Denatured Alcohol) (highly eksempel flammable, harmful 50 cm3. Access to a nitrogen cylinder (optional). Refer to health safety and Technical notes section below for additional information. Health safety and Technical notes. Read our standard health safety guidance. Wear goggles when preparing the solution. Potassium hydroxide, koh(s (corrosive, irritant) - see cleapss hazcard. Glucose (dextrose c6H12O6(s) - see cleapss hazcard. Methylene blue (harmful) - see cleapss hazcard.
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Demonstration, an alkaline solution of from glucose acts as a reducing agent and reduces added methylene blue from a blue to a colourless form. Shaking the solution raises the concentration of oxygen in the mixture and this oxidises the methylene blue back to its blue form. When the dissolved oxygen has been consumed, the methylene blue is slowly reduced back to its colourless form by the remaining glucose, and the cycle can be repeated many times by further shaking. Lesson organisation, the reactions involved are not part of a normal chemical curriculum, but this experiment has a good visual impact and would be one way of stimulating interest in chemistry, perhaps via an Open day. The demonstration lasts about 3 - 5 minutes, but about 15 - 20 minutes is needed for the preparation beforehand. Apparatus, chemicals, eye protection: goggles should be worn when preparing the solution. For each demonstration: Conical flask (1 dm3 stopper or bung, to fit flask. Potassium hydroxide (corrosive, irritant.