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In chemical laboratories and then use indicators - sometimes for the determination of certain substances, and for the most part to find out the acidity of the environment, because of this property depends on the behavior of substances, and the nature of the reaction. Indicators will need us, as well as it is not always possible to buy them, then try to make them yourself. The feedstock will serve plants: many flowers, fruits, berries, leaves and roots contain colored substances that can change its color in response to some effect. And, getting into an acidic (or alkaline) environment, they clearly signal us about it.

Cooking "raw material" in the summer it is easy to collect in the forest, in the field, in the garden or yard. Take bright flowers - iris, dark tulips and roses, pansies, mallow; type raspberries, blackberries, blueberries, blueberry; stock up on a few red cabbage leaves and young beets.

Since the solutions of the indicators produced by boiling (the broth is something like a broth), then, naturally, they quickly deteriorate-sour, grow mouldy. They should be prepared immediately before experience. Take a bit of stored raw materials (the exact number doesn't matter), put in a test tube, pour in water, put in a water bath and heat until until the solution will not be painted. Each solution after cooling, strain and pour into prepared a clean vial label.

To provide indicators for the whole year, will Zaschita summer petals and berries, place them in separate boxes, and then exactly the same as mentioned above, cook from them broths, separately from each plant.

To find out what the broth is an indicator for a particular environment and how changes its color, it is necessary to conduct the test. Take the pipette a few drops of homemade indicator and add them alternately in an acidic or alkaline solution. The acidic solution can serve as vinegar, and alkaline - solution of washing soda, sodium carbonate. If, for example, to add a bright blue decoction of the flowers of the iris, under the influence of vinegar it will become red, ash - green-blue.

The results of all these experiments carefully record, preferably in a table; an example here we present.

Indicator The color of the solution
source in the acidic environment in alkaline medium
Grape juice Dark red Red Green
Blue iris Bright blue Red Green-blue

Suggest you continue with the table itself.

Not only the leaves and berries can render you a service as indicators. To change the acidity clearly react by changing color some juices (including red cabbage, cherry, black grape, black currant) and even fruit drinks.

The role of the indicator can an ordinary soup. This lady known for a long time and use such property beet broth, but not for analysis. That the soup was bright red in it before end of cooking add a little food acids - vinegar or lemon; color changing before our eyes.

Laboratories are widely used indicator phenolphthalein. Prepare it from pharmacy tablets of the same name. One or two tablets grind and dissolve in about 10 ml of vodka (in the extreme case, just in warm water). In any case, the tablet will not dissolve completely, because in addition to the basic substance, phenolphthalein, in them there is a filler is talc or chalk. Filter the resulting solution through blotting paper, and pour in a clean bottle with the label "phenolphthalein indicator. This colorless solution with time is not wasted. It will be useful, and not once, for determining alkaline environment: in it, he immediately blushes. To test, add a drop or two of phenolphthalein to the solution of washing soda.

And last on the vegetative indicators. Once it was in Vogue to write the invitation on the petals of flowers; and he wrote them depending on the flower and the desired color labels solution of acid or alkali, using a thin pen or pointed stick. Try, if you want to write that way, but the petals and solutions to pick up letters independently. Keep in mind that the solution should not be too concentrated, otherwise you may damage the delicate petals.

O. Holguín. "Experiments without explosions"
M., "Chemistry", 1986


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2014-06-15 17:33:06
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