In the school laboratory and at home, you can get beautiful single crystals or clusters of small crystals, cover them with different objects (paper clips, figures from threads, paper). How to grow crystals from salt dissolved in water? Everyone who wants to carry out this interesting experience will require accuracy, attention and accurate implementation of the instructions.
What is crystallization?
When a substance is dissolved in water, its particles pass into solution. The inverse phenomenon is called crystallization. This process is associated with a change in the solubility of the substance at different temperatures. Upon gradual cooling, crystals precipitate from the saturated solution. In shape, the resulting particles are similar to cubes, rhombuses with sharp, straight edges and smooth sides. Various compounds are suitable for conducting the experiment: sodium chloride, sugar, potassium dichromate, vitriol and other substances. They give crystals of different shapes and colors. The most accessible of water-soluble compounds is salt. The substance is safe for humans, does not cause burns if it gets on the skin or inside the body. Find out how to quickly grow salt crystals.
Useful Tips
When performing the experiment, compliance with simple rules is required. This will allow in a short time to get large crystals of regular shape:
- use demineralized or distilled water;
- grow crystals of substances with good solubility;
- carry out an experiment in clean dishes;
- filter the solution (you can through a paper towel).
The process can be observed, but the tank should not be shaken and moved. Many are interested in how to grow crystals from salt, so that they are a certain size. It all depends on the temperature at which the saturated solution is located, as well as on the presence of undissolved particles and impurities.
With slow cooling, large crystals fall out, and with fast cooling - a lot of medium and small ones. To cool, a jar of solution is left in a cold room or placed in a bowl with water and pieces of ice.
What equipment will be required for experience?
Laboratory work "Growing salt crystals" can be successfully performed at home. Very simple objects and substances will be required:
- glass flask or glass (you can take a jar);
- pan for heating in a water bath;
- a bowl of cold water in which the saturated solution will cool;
- stirring stick (glass or wooden);
- funnel and filter paper (paper towel);
- thermometer for water;
- copper wire, paper clip;
- threads
- ice cream stick or pencil;
- half a glass of salt;
- demineralized water.
How to make crystals from salt? Instructions for laboratory work
In advance, select the largest of the salt crystals, they will serve as seed particles. Tie them to a thread, wrap it with an ice cream stick (pencil). For now, set aside this stock and prepare a saturated solution. The use of a heating device will be required. Be careful not to spill hot water or burn from the burner.
Working process:
- Pour one teaspoon of table salt in a jar of water and place in a water bath (90 ° C). Constantly stir the liquid with a stick until the portion of salt is completely dissolved.
- Keep adding substance until it dissolves. Assume that at 100 ° C 39.2 g of sodium chloride are dissolved in 100 ml of water.
- Once saturation is reached, complete the heating. Filter the hot liquid into another jar.
- Dip a thread with a particle into the solution that has not yet cooled to initiate the process.
After a while, a crystal of salt will grow. It needs to be taken out and dried on a paper towel. It is possible to conduct an experiment without initiating crystallization or to lower a metal clip attached to a thread. Crystals will grow on it. If you coat them with colorless varnish, they will be better preserved.
How to get blue crystals?
Copper sulfate is highly soluble in water. Large blue crystals can be grown from this substance. Only you need to carefully conduct the experiment - the compound is toxic. How to grow crystals from salt, which is the crystalline hydrate of copper sulfate? Large and very beautiful specimens can be grown by placing an initiating particle in the solution. To obtain it, a little supersaturated solution of copper sulfate is poured into a saucer and left overnight. From the precipitated crystals, choose the one that is larger, tied to a silk thread and immersed in a hot saturated solution so that it does not touch the walls and bottom of the can. In the air, bound water will evaporate from copper sulfate, it will turn into a faded greenish powder of copper sulfate. It is necessary to dry the finished crystal and varnish it.
How to grow salt crystals in the form of letters and figures?
In banks, according to the instructions, prepare a saturated solution of salt, copper sulfate, sugar, potassium dichromate (in different dishes). For white substances, food coloring can be used. Make a figure or letter out of thin wire. Gently wrap it with white wool threads. Dip the prepared suspension frames in supersaturated solutions that have not cooled down so that they do not touch the bottom and walls of the cans. In a day or even faster, the figures will be covered with crystals. Remove them, dry on a paper towel and cover with colorless nail polish. A few ideas for using grown crystals:
- school presentation on the topic “Solutions”;
- preparation of a report on laboratory work;
- decoration of the festive wall newspaper;
- making Christmas tree toys;
- gifts to friends, teacher, parents;
- creating a collection of grown crystals.