Is it possible to grow crystals at home? Let’s try together to find the answer to this question, to propose methods for conducting this experiment.
We are well aware that crystals of various shapes and sizes can be found in nature. In winter, snowflakes adorn windows, tree branches. Some crystals are vital products of certain organisms.
Introduction
For example, crystal growth is characteristic of mollusks that enter the shell. After 5-10 years, a beautiful pearl is formed in it, unique in its appearance and unique brilliance.
As crystals, sapphires, rubies, diamonds, and other precious stones can be considered. The importance of natural crystals in industry, science, electronics, and optics is great.
Growing crystals at home is a fascinating activity available for beginner chemists and researchers. It is safe and therefore suitable even for elementary school students.
Thanks to careful preparation, accurate execution of the experiment, the formation and development of skills for setting up experiments takes place.
It is important to start growing crystals after ideas about the aggregate states of matter and methods for controlling the crystal growth process are formed.
If crystallization proceeds at an insignificant rate, one can count on obtaining a large crystal. With an increase in the speed of the process, one can count on obtaining polycrystalline small crystals.
Important information
The Crystal Growing project can be started with theoretical terms and concepts. Crystals are called the solid state of a substance. It is characterized by a certain shape, the number of faces associated with the specific arrangement of atoms. Crystals of one substance always have the same shape, but size differences are allowed.
Crystal growth is associated with a change in the thermodynamic parameters of the solution, the transition of the solution to a solid state of aggregation.
In nature, there are many diverse substances that can form crystals.
For example, growing water crystals involves lowering the temperature. During freezing, water forms snowflakes or ice crystals. According to a similar pattern, mineral crystals are formed during certain rock-forming processes.
Significant amounts of molten and hot rocks located in the bowels of the earth are mineral solutions.
When they are pushed to the surface of the earth, slow cooling occurs, which leads to the transition to solid form.
For example, mountain granite contains crystals of minerals: feldspar, quartz, and mica. Millions of years ago, granite existed in the form of a molten mass of minerals. Nowadays, there are various molten rocks in the earth's crust, with the gradual cooling of which various types of crystals form.
The methods for growing crystals vary and depend on the chemical structure of the substance, the temperature regime, and the use of additional components.
Process specifics
The process can be divided into several separate points:
- natural, associated with education in nature;
- artificial.
The second option is in demand in the following cases:
- for scientific and technical purposes;
- during extracurricular, practical, experimental work;
- random crystal formation.
How can crystal growth occur in the latter case? Chemistry considers such an option of crystallization as an unintended outcome of an experiment in which in this case no control by the researcher was supposed. Spontaneous crystallization is observed in the presence of additional physical or chemical processes: evaporation of the solvent, oxidation of the components of the solution.
Physicochemical Characterization
The growth of crystals from salt is explained by the solubility of the substance in solvents, accompanied by the destruction of the crystal structure. The heat required for such a process is taken from the environment. For example, in the case of dissolution of ammonium thiocyanate NH 4 SCN and potassium iodide, the temperature change can be felt by direct contact with the tube.
Also, growing crystals from salt at home is associated with diffusion. For example, taking several crystals of potassium permanganate (potassium permanganate) and dissolving them in water, you can observe how pink swirls form in the volume of the cylinder. With vigorous stirring, the entire solution acquires a uniform pink color. If it is frozen, you can count on getting beautiful potassium permanganate crystals.
Crystal growth for children is best seen on sodium chloride, copper sulfate (2).
Important aspects
When selecting material for experimental work, it is important to consider certain facts:
- The starting material should not be toxic. For example, the project "Growing crystals at home" for children does not allow the use of potassium cyanide, sodium sulfate, since the hydrolysis of such salts releases toxic compounds that can cause poisoning.
- Selected substances should give stable results. For example, crystals of sodium sulfate, iron-ammonium and chromium-potassium alum, manganese salts, when moisture is lost, turn into nondescript powders, and therefore, they are not included in the kit for growing crystals.
- Reasonable cost and availability of selected reagents. How can crystals be grown? Kits for children include available components, as well as detailed recommendations for doing practical work.
- Use of stable substances. It is not recommended the choice of substances that undergo reversible hydrolysis. So, ammonium salts, characterized by high hygroscopicity, will react with water, as a result of which it will be difficult to count on obtaining the desired result.
What else should a young alchemist know? Crystal growth involves a certain sequence of actions (algorithm). Only if all the requirements, stages of work are met, can one count on obtaining the desired result.
It is desirable to store crystals in the refrigerator, so as not to provoke their destruction. There are some substances that can exist in a stable crystalline form for a rather long time period.
For example, the best option for schoolchildren is to grow crystals from copper sulfate, table salt. These components are available in a price range, they are suitable for their chemical-physical, biological characteristics.
With an additional coating of the obtained crystals with a colorless varnish, their “lifespan” can be significantly extended.
Necessary equipment
How to grow crystals? Kits for children include chemical glassware: heat-resistant glasses, filter paper, funnel, glass rod, reagents.
If the experiment is carried out at home, instead of filter paper, toilet paper (napkins) is allowed, and the role of a water bath can be played by an old pan placed on an electric stove.
An alternative for a real chemical funnel is the neck of an old plastic bottle.
What else is important to consider when conducting the experiment "Growing crystals"? In addition to direct cultivation, it is important to gain skills in maintaining the result of experimental activity.
Education Options
There are three different options for crystal formation:
- from the melt;
- from solution;
- from the gas phase.
As an example of crystallization from the molten state, the appearance of ice from water, as well as the formation of volcanic rocks, can be noted.
Crystal growth from vitriol is a typical example of the transition from the liquid phase to the solid state of aggregation.
In the case of cooling of steam or gas, due to the electric forces of attraction, the union of atoms or molecules into a crystalline state is observed. Among the most common options for the artificial production of single crystals that can be carried out by elementary school students, let us single out the growth of crystals from copper sulfate. The complexity of the process lies in the insignificant speed of its course.
An example of design work of a student
The relevance of the topic is that detailed instructions for growing crystals were given, as well as concrete results were achieved.
Project hypothesis: at home, you can grow beautiful and unique crystals.
Project goal: Growing salt crystals on your own.
Project Objectives:
- to analyze the theoretical information on the research issue;
- to identify the importance of salt for human life;
- with your own hands to grow crystals of table salt;
- specify the conditions for the formation of crystals;
- evaluate the results obtained in the course of practical activity.
Historical reference
Sodium chloride is a common food product. In nature, this compound is found as a halite mineral, also called "rock salt". Sodium chloride is present in significant quantities in seawater. This compound was found in the bowels of the earth, on the banks of rivers, in the mountains.
Without a certain amount of table salt, many living organisms begin salt starvation. Predators fill the deficit of sodium chloride with meat and blood of prey, herbivores lick salty soils.
A person needs 10-15 grams of table salt per day (no more than 1 tablespoon), an excess of this chemical leads to kidney disease. In ancient times, salt was used to make coins; a slave could be purchased on 5 tiles of salt.
In ancient Rome, hired soldiers received a salary precisely with salt, and not with money. The British believed that a solution of sodium chloride, sprinkled on a thing, prevents misfortune. It was salt that was considered a symbol of friendship and hospitality. There is a popular sign, according to which, when it is scattered, it is necessary to prepare for failure, a quarrel.
The substance got into Kievan Rus from the salt lakes of the Azov and Black Seas. It was such an expensive commodity that they served it only for noble guests.
There are cities that appeared on the sites of extraction of sodium chloride:
- Solikamsk.
- Solvychegodsk.
- Bursol.
- Solikamsk.
- Soligalich.
- Sol-Iletsk.
Interesting about crystals
Translated from the Greek language, the word means "ice". They have a diverse shape, structure, size. For example, giant specimens reach a mass of several tons. Ancient people believed that it was possible to obtain crystal from ice, and to obtain diamonds from crystal. They were endowed with magical properties, believed that crystals heal from deadly diseases, affect the fate and life of a person.
There are special forms of crystals: branches, feathers, needles, trees, flowers. An example is the patterns on the windows in the winter. People have learned to grow rubies artificially. Stones are needed for the jewelry industry, as well as for the manufacture of precision watch movements.
Practice
Growing crystals of salt does not imply special chemicals. Each house has salt that is eaten. The crystals of this chemical compound are transparent, colorless cubes. The procedure for growing crystals from table salt was divided into several stages:
- Dissolution of salt in warm water. The process continued until such a moment arrived, until the substance ceased to dissolve (saturated solution).
- The prepared mixture is poured into another container in which it is possible to grow the final crystals. In order that the specks do not interfere with the crystallization process, the solution is preliminarily filtered through a tissue or toilet paper.
- A small pebble is attached to the thread, which is lowered into the prepared solution.
- The container is covered with metallized foil to prevent debris and dust from getting inside.
Important points
In order to get large and beautiful crystals, it is undesirable to pull out pebbles without special need.
Debris should not get into the saturated solution, as this will lead to a decrease in the rate of crystallization and will adversely affect the size of the particles formed.
No need to use paints in the process of growing crystals, as this will not only spoil the solution itself, but also negatively affect the final result.
Judging by the reviews, the first crystals on the thread are formed 2-3 days after the start of the experiment. Gradually they increase in size, grow on each other. In the end, a sufficiently large transparent crystal of sodium chloride is formed.
Cultivation of crystals of copper sulfate
To obtain beautiful particles of copper sulfate, copper sulfate powder can be purchased at a hardware store. This substance is used in agriculture to combat harmful microorganisms that destroy vegetable and fruit crops.
It must be remembered that copper sulfate is an active chemical compound. It is poisonous! You need to wash your hands after the process of dissolving the powder, as well as when working with crystals of copper sulfate.
First you need to prepare a saturated solution of this salt. To do this, the powder dissolves in hot water until the dissolution process stops. Next, a small pebble (seed) is attached to the thread, it is suspended in a container with a solution of copper sulfate so that it does not touch the bottom. The vessel is left open for a long period, room temperature is maintained. In order to prevent ingress of debris and dust, the container can be covered with food foil.
During evaporation, a crust will appear on the surface of the solution, gradually turning into shiny blue crystals. After 3-4 days, the “seed” is overgrown with blue crystals resembling precious stones. Three weeks later, you can get a large crystal of copper sulfate.
If you wish, you can arm yourself with a ready-made set of a young chemist, designed to grow a variety of crystals.
Ammonium dihydrogen phosphate is used as a substance, in which a food-grade powder dye is added. Also in the kit there are pebbles necessary for “seed”, a plastic container with a lid and graduated divisions for growing, tweezers, a magnifying glass, a spatula for mixing.
For the experiment, 40 ml of hot water is measured, then the mixture is poured, it is dissolved in water with stirring with a spatula. The main rock is scattered along the bottom of the container, the solution is poured into the tank. It is placed in a bright place, for example, on a windowsill. As the water evaporates, needle crystals of salt appear in the container. After 2-3 weeks, the water will completely evaporate; large crystals of ammonium salt can be observed.
Finally
When conducting research on the algorithm proposed earlier, you can count on the implementation of the task. Crystals grown at home are quite large.
In the course of independent experiments, the young chemist can draw the following conclusions:
- compare the crystal growth process of various chemicals;
- analyze the differences in color, size, shape of the grown crystals;
- particles can grow when removing weeds, getting rid of unwanted growths;
- the crystal growth process is carried out as water evaporates;
- their shape and size is affected by the temperature indicator.
Judging by the reviews, the crystals are quite capricious, they need a careful attitude to them, full compliance with the temperature regime, the sequence of actions, the use of "seed". If you have patience, carefully and carefully treat this project, it is quite possible to grow crystals of unusual shape, color, size at home.
We must not forget that man needs crystalline substances for the manufacture of machine tools, the construction of houses, and domestic purposes.
In the bowels of the earth there are stones of such an ideal shape, as if someone had polished them, polished them, and sawed them with high quality.
Each of us was surprised to examine flawless snowflakes, small grains of sand on the banks of the river, admiring the precious and semiprecious stones.
It is hard to believe that it was nature, without any human intervention, that created these crystalline substances.
To instill a cognitive interest in inorganic chemistry, to develop skills in project and research activities, to prepare the younger generation for the upcoming choice of a profession, experiments related to the cultivation of crystals of copper sulfate, table salt at home can be considered an ideal option. In the process of practical activity, schoolchildren get acquainted with theoretical materials, skills of experimental activity, study the basic safety rules.