О производстве спичек

An invisible letters.


There is a table a vial 50% solution of acerbic wax, cobalt (II) of the chloride, solution colorless phenolphthalein, a sprayer of Perfume, alcohol lamp, porcelain cups, the word “Welcome» which is written on paper on the stage. The Pupil 8 classes Erkin is writing at the table, Yulduz tries to hang the paperboard on board. On scene appear Halima and Ruhsora.

Halima: What are you writing Erkin ака?

Erkin:I am writing the announcements for mug of the chemistries.
Ruhsor (looking at paper of Erkin) Erkin ака there is not anything on paper.
Couldn`t you find a good pen?
Erkin: Why it is not seen. Look attentively and you can read.
Halima (takes a letter from letter Erkin, puts on light and with Ruhsora have not seen anything) See, there is not anything on paper.
Yulduz (having hung paperboard on board) It is not important for everybody to to see it, it can read only participants mug of chemistries.
Ruhsora (with fury to Yulduz): What do you mean?
Erkin: Stop. (Looking at Halima) If can not see ask me, I will show you.
Ruhsora :if there is nothing to see f there were anything ,we could see it ourselves.
Erkin: Why are you so angry? I think if I don’t show you, what is written you may offend .See please. (Erkin put the paper above the alcohol and heats it a little, after heating, there appeared a beautiful blue inscription "announcement"
Ruhsora reads this word aloud, now and Halima with surprise looked at this announcement.
Erkin: Well what have you seen record?
Ruhsora (taking a paper from Erkin, she shows it to spectators.)What kind of pen have you used?
Erkin: I will explain you the secret of this ink (shows on cup). This is not a paint but solution of cobalt (II)-chloride in water. The Chemical formula is (SOSL2. 6 N2O), this is a composition of the salts 6 molecules crystal water and thus it has a weakly orange color. If heat a little, it changes into the blue color.
Yulduz : Because the color of arid cobalt (II)-chloride salt has a blue color without a water.
Halima: Have you understood?
Ruhsora (showing the paperboard hung on board) If warm this paper will appear the inscription.
Erkin: No,there is other secret.
Halima: What is the secret?
Erkin: The secret of this letter will comes out (showing the sprayer of perfume) from this sprayer.
Ruhsora: How it can do it?
Erkin: Watch. (He takes the sprayer and sprays colorless liquid on paper. There appeared a word “Welcome comrades!» in red color
Halima: (takes the sprayer): Is this water?
Yulduz : This not a water, but solution of acerbic wax.
Erkin: You know that if alkalis reacts to phenolphthalein, which is colorless material,will give a red color . On the paper was written with the solution of phenolphthalein in alcohol .The liquid is colorless, thus isn’t seen anything. After spraying the liquid of alkalis, theletters appears in red color.
Ruhsora: Is it possible to hide these letters again?
Yulduz : Yes, it is this possible.
Erkin: If we spray on paper the solution of the acid, acid reacts with alkali and forms salt and alkali disappears. As a result phenolphthalein becomes colorless. (In this time Yulduz installed sprayer in gas in vial with salt acid and begin to spray, inscription disappears.)
Halima: Thank you Erkin ака! We have seen these unencumbered letters for the first time, so in the beginning have not believed, and you have offended.
Ruhsora: Yulduz , You also forgive us.
Erkin: Ok .It is useful ask that do not know.
Halima:
Erkin: Good bye, happy journey.
(Halima and Ruhsora leave, Erkin continues to write, curtain is closed).