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 know perfectly well that crystals of various shapes and sizes can be found in nature. In winter, snowflakes decorate windows, tree branches. Some of the crystals are the waste products of certain organisms.
Intro
For example, the growth of crystals is typical for mollusks that fall into the shell. After 5-10 years, a beautiful pearl is formed in it, unique in its appearance and unique brilliance.
Sapphires, rubies, diamonds, and other precious stones can be considered as crystals. The importance of natural crystals in industry, science, electronics, optics is great.
Growing crystals at home is a fun activity for beginner research chemists. It is safe, so it is suitable even for elementary school students.
Through meticulous preparation, meticulous executionexperiment, the formation and development of the skills of setting up experiments takes place.
It is important to start growing crystals after ideas about the aggregate states of matter, ways to control the process of crystal growth.
If crystallization proceeds at a low rate, you can count on getting a large crystal. By increasing the speed of the process, you can expect to obtain polycrystalline small crystals.
Important information
The Crystal Growing Project can be started with theoretical terms and concepts. Crystals are the solid state of matter. It is characterized by a certain shape, the number of faces associated with the specifics of the arrangement of atoms. Crystals of the same substance always have the same shape, but differences in size are allowed.
Growing crystals is associated with a change in the thermodynamic parameters of the solution, the transition of the solution into a solid state of aggregation.
In nature, there are many different substances that can form crystals.
For example, growing water crystals involves lowering the temperature. As water freezes, it forms snowflakes or ice crystals. According to a similar scheme, the formation of mineral crystals is carried out during certain rock-forming processes.
Significant amounts of molten and hot rocks in the earth's interior are mineral solutions.
When pushing them to the surfaceearth, a slow cooling occurs, which leads to a transition to a solid form.
For example, mountain granite contains crystals of minerals: feldspar, quartz, mica. Millions of years ago, granite existed as a molten mass of minerals. In our time, there are various molten rocks in the earth's crust, with the gradual cooling of which crystals of various types are formed.
Methods of growing crystals vary and depend on the chemical structure of the substance, temperature, 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;
- when conducting extracurricular, practical, experimental work;
- random crystal formation.
How can crystal growth take place in the latter case? Chemistry considers this variant of crystallization as an unintended outcome of the experiment, in which in this case there was no control on the part of the researcher. Spontaneous crystallization is observed in the presence of additional physical or chemical processes: evaporation of the solvent, oxidation of the components of the solution.
Physical and chemical characteristics
Growing crystalsfrom s alt 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 dissolving ammonium thiocyanate NH4SCN and potassium iodide, the temperature change can be felt by direct contact with the test tube.
Also, growing crystals from s alt at home is associated with diffusion. For example, by taking several crystals of potassium permanganate (potassium permanganate) and dissolving them in water, one can observe how pink swirls form over 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 crystals of potassium permanganate.
Growing crystals for children is best considered on sodium chloride, copper sulfate (2).
Important aspects
When selecting material for experimental work, it is important to consider certain facts:
- The starting material must not be toxic. For example, the "Growing crystals at home" project for children does not allow the use of potassium cyanide, sodium sulfate, since the hydrolysis of such s alts releases toxic compounds that can cause poisoning.
- The substances chosen must give stable results. For example, sodium sulfate crystals, iron-ammonium and chromium-potassium alum, manganese s alts, with loss of moisture, turn into nondescript powders, and therefore, theyare not included in the crystal growing kit.
- Acceptable cost and availability of selected reagents. How can crystals be grown? Kits for children include accessible components as well as detailed instructions for doing practical work.
- Use of stable substances. The choice of substances that undergo reversible hydrolysis is not recommended. Thus, ammonium s alts, which are highly hygroscopic, will react with water, as a result of which it will be difficult to expect to obtain the desired result.
What else should a young alchemist know? Growing crystals involves a certain sequence of actions (algorithm). Only if all the requirements and stages of work are met, you can count on getting the desired result.
Store crystals preferably in the refrigerator, so as not to provoke their destruction. There are some substances that are able to exist in a stable crystalline form for quite a long time period.
For example, the best option for schoolchildren is to grow crystals from copper sulfate, s alt. These components are available in a price range, suitable for their chemical-physical, biological characteristics.
With an additional coating of the obtained crystals with a colorless varnish, you can significantly extend their "lifetime".
Equipment required
How to grow crystals? Sets for children include chemical glassware: heat-resistant glasses,filter paper, funnel, glass rod, reagents.
If the experiment is carried out at home, toilet paper (napkins) can be used instead of filter paper, and an old pot placed on an electric stove can play the role of a water bath.
An alternative to a real chemical funnel is the neck of an old plastic bottle.
What else is important to consider when doing a Crystal Growing experiment? In addition to direct cultivation, it is important to acquire the skills to preserve the result of experimental activities.
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 a molten state, we can note the appearance of ice from water, as well as the formation of volcanic rocks.
Growing crystals from vitriol is a typical example of the transition from a liquid phase to a solid state of aggregation.
In the case of cooling of a vapor or gas, due to electric forces of attraction, the association of atoms or molecules into a crystalline state is observed. Among the most common options for the artificial production of single crystals, which can be carried out by elementary school students, we single out the cultivation of crystals from copper sulphate. The complexity of the process lies in the insignificant speed of its flow.
An example of student project work
The relevance of the topic is that it was givendetailed instructions for growing crystals, as well as specific results.
The hypothesis of the project: beautiful and unique crystals can be grown at home.
The goal of the project: growing s alt crystals on our own.
Project Objectives:
- analyze theoretical information on the research question;
- reveal the value of s alt for human life;
- grow s alt crystals with your own hands;
- clarify the conditions for the formation of crystals;
- evaluate the results obtained in the course of practical activities.
Historical background
Sodium chloride is a common food product. In nature, this compound occurs as the mineral halite, also referred to as "rock s alt". Sodium chloride is found in significant amounts in sea water. This compound was found in the bowels of the earth, on the banks of rivers, in the mountains.
Without a certain amount of table s alt, many living organisms begin s alt starvation. Predators make up for the lack of sodium chloride with the meat and blood of prey, herbivores lick s alty soils.
10-15 grams of table s alt (no more than 1 tablespoon) is enough per day for a person, an excess of this chemical leads to kidney diseases. In ancient times, s alt was used to make coins, for 5 tiles of s alt you could buy a slave.
In ancient Rome, hired soldiers were paid with s alt, not money. The British believed that a solution of sodium chloride,splashed on a thing, prevents misfortune. It was s alt that was considered a symbol of friendship and hospitality. There is a popular sign, according to which, when it is scattered, you need to prepare for failure, a quarrel.
In Kievan Rus, the substance came from the s alt lakes of the Azov and Black Seas. It was such an expensive commodity that it was served only for noble guests.
There are cities that appeared on the places where sodium chloride was mined:
- Solikamsk.
- Solvychegodsk.
- Bursol.
- Solikamsk.
- Soligalich.
- Sol-Iletsk.
Interesting about crystals
The word means "ice" in Greek. They have a variety of shapes, structures, sizes. For example, giant samples reach a mass of several tons. Ancient people believed that crystal could be obtained from ice, and diamonds could be obtained from crystal. They were endowed with magical properties, they 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 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 s alt crystals does not involve special chemicals. Every home has s alt for food. The crystals of this chemical compound aretransparent colorless cubes. The procedure for growing s alt crystals was divided into several stages:
- Dissolving s alt in warm water. The process continued until such a moment came, until the substance ceased to dissolve (saturated solution).
- The prepared mixture is poured into another container, in which the final crystals can be grown. In order for the motes not to interfere with the crystallization process, the solution is first filtered through a napkin or toilet paper.
- A small pebble is tied to a 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 a pebble without special need.
Debris should not get into the saturated solution, as this will lead to a decrease in the crystallization rate, and will negatively affect the size of the particles formed.
Don't use dyes when 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 top of each other. Eventually, a fairly large transparent crystal of sodium chloride is formed.
Cultivation of copper sulfate crystals
To get beautiful sulfate particlescopper can be purchased at the hardware store copper sulfate powder. 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's poisonous! It is necessary to wash hands after the process of dissolving the powder, as well as when working with copper sulfate crystals.
First you need to prepare a saturated solution of this s alt. To do this, the powder is dissolved 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 time, room temperature is maintained. In order to prevent debris and dust from getting inside, the container can be covered with food foil.
In the course of evaporation, a crust will appear on the surface of the solution, gradually turning into blue shiny crystals. After 3-4 days, the "seed" is overgrown with blue crystals resembling precious stones. After three weeks, 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, to which powdered food coloring is added. Also in the set there are pebbles necessary for the "seed", a plastic container with a lid and measured divisions for growing, tweezers,magnifying glass, stirring paddle.
For the experiment, 40 ml of hot water is measured, then the mixture is poured in, it is dissolved in water while stirring with a spatula. The main rock is scattered along the bottom of the container, the solution is poured into the container. It is placed in a bright place, for example, on a windowsill. As the water evaporates, needle-shaped s alt crystals appear in the container. After 2-3 weeks, the water will completely evaporate, you can see large crystals of ammonium s alt.
In closing
When carrying out research work according to the algorithm proposed earlier, one can count on the implementation of the task. Crystals grown at home are quite large.
During independent experiments, a young chemist can draw the following conclusions:
- compare the crystal growth process of various chemicals;
- analyze differences in color, size, shape of grown crystals;
- particles can grow when removing weeds, getting rid of unwanted growths;
- the process of crystal growth is carried out as water evaporates;
- their shape and size is affected by temperature.
Judging by the reviews, the crystals are quite capricious, they need to be treated with care, full observance of 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 an unusual shape, color, size at home on your own.
We must not forget that crystalline substances are needed by a person for the manufacture of machine tools, construction of houses, domestic purposes.
In the bowels of the earth there are stones of such an ideal shape, as if someone had polished, polished, cut them with high quality.
Each of us looked with surprise at the flawless snowflakes, small grains of sand on the river bank, admired precious and semiprecious stones.
It's hard to believe that it was nature, without any human intervention, that created these crystalline substances.
In the process of practical activities, students get acquainted with theoretical materials, skills of experimental activities, study the basic safety rules.
