Water into wine: Seconds
A fresh bottle of water is opened and some is drunk by the experimenter. The experimenter explains that it is nice to have something other than water and water is poured from the bottle into a wine glass which appears now to contain apple juice. The experimenter then suggests that coke might be more appropriate and the apple juice is poured into a second wine glass. The solution turns a dark colour giving it the appearance of coke. Finally the experimenter decides to try to get back to water and pours the coke into a third glass where it loses its colour. More water is poured into a fourth glass which now appears to contain a berry juice. Glucose is added to the berry juice and turns it gradually (from the bottom) a light orange.
- Four wine glasses.
- A bottle of water.
- Tincture of iodine.
- Starch solution.
- Vitamin C.
- Potassium permanganate.
- Caustic soda.
Make solutions as follows:
Tincture of iodine may be used directly as bought in a pharmacy.
Starch solution is made by adding a little boiling water to a small quantity (less than a quarter of a teaspoon) of Maizena (cornflour, corn starch). This should then be boiled and the resulting solution should be appreciably viscous. Add more boiling water if the starch starts to become solid. Dissolve one effervescent tablet of vitamin C in no more than 30 mL of water.
Make a small amount (30 mL) of an almost saturated solution of potassium permanganate and add half a teaspoon of caustic soda.
Place 10 – 15 drops of each of the solutions into the wine glasses. The first glass should contain the tincture of iodine, the second the starch solution, the third the vitamin C and the fourth the alkaline potassium permanganate.
The water poured into the first glass is simple coloured by the iodine tincture and looks a bit like apple juice.
The iodine reacts with the starch in the second glass to produce a deep blue colour, which can appear black if the concentrations are correct.
The vitamin C in the third glass acts as a reducing agent to reduce the iodine to iodide which removes the deep blue colouration.
In the fourth and final glass the potassium permanganate is a deep purple colour. The permanganate ion gives the solution its strong colour and is a strong oxidising agent. The permanganate oxidises the glucose and in the process becomes reduced to different forms of the manganate ion which changes the colour. The colour changes from the bottom up because the glucose sinks and is a high concentration at the bottom of the glass.
Check that your solutions give the right effects before doing this before an audience. There may be local variations in ingredients.
The final solution, with potassium permanganate, is sometimes difficult to see as it depends quite sensitively on the concentration of the solution.
Most of these solutions may be kept successfully in sealed bottles for a number of months. Beware, however, that the starch solution may start to grow organic matter.
Only drink from the water bottle, not from any of the solutions that you have made.
Only drink from the freshly opened bottle of water. Take care with iodine – it will stain (but stains can often be removed by applying vitamin C solution). Potassium permanganate is a powerful oxidising agent and should be treated with care and stored appropriately.
Take appropriate precautions when preparing the starch solution as one is dealing with boiling water and hot solutions.