Glass of water
Liquid glass is a concentrated solution of sodium metasilicate Na2SiO3 (potassium salt is also used). It is made by dissolving silica (like sand) in a sodium hydroxide solution:
Glass of water in fact, it is a mixture of salts of various silicic acids with different degrees of polymerization. It is used as an impregnation (for example, to protect walls from moisture, as a fire protection), a component of putties and sealants, for the production of silicone materials, as well as a food additive to prevent caking (E 550). Commercially available liquid glass can be used for several spectacular experiments (because it is a thick syrupy liquid, it is used diluted 1:1 with water).
In the first experiment, we will precipitate a mixture of silicic acids. For the test, we will use the following solutions: liquid glass and ammonium chloride NH.4Cl and indicator paper to check the reaction (photo 1).
Chemistry - part of liquid glass 1 - MT
Liquid glass as a salt of a weak acid and a strong base in an aqueous solution is largely hydrolyzed and is alkaline (photo 2). Pour the ammonium chloride solution (photo 3) into the beaker with the water glass solution and stir the contents (photo 4). After some time, a gelatinous mass is formed (photo 5), which is a mixture of silicic acids:
(actually SiO2? нГн2ABOUT ? silicic acids with varying degrees of hydration are formed).
The beaker reaction mechanism represented by the above summary equation is as follows:
a) sodium metasilicate in solution dissociates and undergoes hydrolysis:
b) ammonium ions react with hydroxide ions:
As hydroxyl ions are consumed in reaction b), the equilibrium of reaction a) shifts to the right and, as a result, silicic acids precipitate.
In the second experiment, we grow "chemical plants". The following solutions will be required for the experiment: liquid glass and metal salts? iron (III), iron (II), copper (II), calcium, tin (II), chromium (III), manganese (II).
Chemistry - part of liquid glass 2 - MT
Let's start the experiment by introducing several crystals of iron chloride (III) salt FeCl into a test tube.3 and a solution of liquid glass (photo 6). After a while, brown?plants? (photo 7, 8, 9), from insoluble iron (III) metasilicate:
Also, salts of other metals allow you to get effective results:
- copper(II)? photo 10
- chromium(III)? photo 11
- iron(II)? photo 12
- calcium? photo 13
- manganese(II)? photo 14
- tin(II)? photo 15
The mechanism of the ongoing processes is based on the phenomenon of osmosis, i.e., the penetration of small particles through the pores of semipermeable membranes. Deposits of insoluble metal silicates form as a thin layer on the surface of the salt introduced into the test tube. Water molecules penetrate into the pores of the resulting membrane, causing the metal salt underneath to dissolve. The resulting solution pushes the film until it bursts. After pouring out the metal salt solution, does the silicate precipitate re-precipitate? the cycle repeats itself and the chemical plant? increases.
By placing a mixture of salt crystals of various metals in one vessel and watering it with a solution of liquid glass, can we grow a whole “chemical garden”? (photo 16, 17, 18).
Photos
