How to evaporate salt from water is the purpose of the work. Method for evaporating solutions with crystallization of salts
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Evaporation of the salt solution is controlled by specific gravity, crystallization and centrifugation - according to the quality of the resulting sodium acetate, processing of mother liquors - according to their quality (content of sodium formic acid and reducing substances), according to the content of sodium acetate in the waste discharged into the sewer, and according to their alkalinity.
Salt solutions are evaporated in steam-heated evaporators.
When the magnesium salt solution is evaporated, the hydrochloric acid formed during hydrolysis is gradually distilled off, and the hydrolysis goes further and further.
So, when a salt solution is evaporated, small cubic crystals of solid salt are formed. These cubic crystals are limited by flat square faces.
Nitrates are obtained by evaporating solutions of Zr and Hf salts with HNOS Oka are colorless compounds. All salts, except for the last two, are hydrolyzed in aqueous solutions which are strongly acidic.
On fig. 2 shows the modern design of an apparatus with a submersible burner for evaporating salt solutions. For uniform distribution of flue gases bubbling in the liquid, the submersible burner is equipped with a grate bubbler and a guide cone located at the mouth of the nozzle.
Main stages technological process sodium acetate production are: neutralization acetic acid, salt solution evaporation, salt crystallization and centrifugation, processing of mother liquors.
Apparatuses with a submersible burner located in the central part of the body are used for evaporating salt solutions. Crystallized salts are removed using a special valve installed in the lower part of the cone bottom. The steam-gas mixture is discharged through a pipe installed on the cover of the apparatus, inside which baffle plates are placed to separate drops of the solution. Disks with cylindrical or slotted holes are used as a bubbler in such devices. This increases the contact surface and intensifies the processes of heat and mass transfer. The disadvantage of such devices is the uneven distribution of gas over the cross section of the disk, especially in devices large sizes, and also, the lack of liquid circulation in the lower part of the apparatus.
| Typical device design. |
Apparatuses with a submersible burner located in the central part of the vessel are used to evaporate salt solutions. The required level of the solution in the apparatus / is set using a drain pipe 6 with a movable nozzle. Crystallized salts are removed through the lower fitting of the cone bottom using a special pulsating valve. On the cover 2 of the apparatus, a pipe 4 is installed to output the vapor-gas mixture. Breakers 5 are placed inside the pipe to separate drops of solution carried away by the steam-gas flow from the apparatus. Submersible burner 3 passes through the steam space of the apparatus, so tunnel-type burners with an elongated combustion chamber should be used.
Volatilization, however, does not occur when dilute hydrochloric acid solutions containing tin (IV) are boiled in vessels covered with watch glass or when hydrochloric-sulfuric acid solutions of salts of this element are evaporated until sulfuric acid vapor appears.
Removal of the vaporization zone from the heating tubes is a reliable way to protect them from encrustations only during the crystallization of salts, the solubility of which increases with increasing temperature. This measure is not enough when evaporating solutions of salts with reverse solubility, since it is near the heat transfer surface that a supersaturated state is formed. In addition, in the riser, where the solution boils rapidly and its maximum supersaturation is maintained, there is a high probability of the formation of encrustations, regardless of the nature of the salt solubility.
The salt solution, separated from mechanical impurities by filtration, was subjected to the action of various reagents. Georgi points out that when the salt solution was evaporated, small cubic crystals formed in it, containing an excess of alkaline salt. To saturate this excess alkaline salt, it was necessary for 5 ounces of salarka 2/2 drachma of vitriol.
With a once-through scheme, there is no need to install intermediate pumps for pumping the solution, which flows by gravity from the first apparatus to the last due to a decrease in pressure in each subsequent housing. However, a gradual decrease in the temperature of the solution as it is concentrated (which can cause premature crystallization and blockage of overflow pipes when evaporating solutions of salts with direct solubility) is a big disadvantage of the once-through scheme and it is usually not used for evaporating crystallizing solutions.
Objectives: - To teach to argue, to hear your friend;
To develop the dialectical thinking of children: their ability to detect transformations in inanimate nature;
To develop formally - logical thinking - the ability to put forward hypotheses, find causal relationships, draw conclusions;
Develop speech, the ability to express and justify your point of view.
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Salt dissolution and evaporation
Objectives: - To teach to argue, to hear your friend;
To develop the dialectical thinking of children: their ability to detect transformations in inanimate nature;
To develop formally - logical thinking - the ability to put forward hypotheses, find causal relationships, draw conclusions;
Develop speech, the ability to express and justify your point of view.
Course progress.
- - Guys, I invite you to our laboratory again. We will be experimenting. But first, let's play.
Game "Say the other way around"
Game "Logic chain"
- - What is experience? (methods used by scientists in the study of science; scientific experiment).
Experience is a scientific experiment. To engage in science, one must be smart, be able to think, draw conclusions. And we want to be like that. To do this, we will conduct brain gymnastics.
Exercise 1 "Tilts and cross movements"
I.p. Standing feet shoulder width apart. We carry the shoulder to the hip, not the elbow to the knee! Head turns slightly as you move. The body seems to be folding, and the arms and legs are only substituted. Don't pinch your mouth. Lips are free.
This exercise increases the activity of a person and energizes him.
Exercise 2 "Brain Button"
Two fingers of one hand under the collarbones - there are two dimples. The second hand rests on the navel. Gently massage the subclavian fossae. We change hands.
Breathing improves, blood runs faster through the vessels, eyes see better.
Exercise 3 "Thinking Cap"
We take ourselves by the ears - by the upper part of the ear: the thumb is behind, the index finger is in front. And gently massage the ears, as if stretching back and twisting a little. We massage several times from top to bottom each point on the edge of the auricle.
Clarity appears in the head, you can quickly collect your thoughts.
Exercise 4 "Owl"
We take the left shoulder in the middle with the right hand. We turn our heads slightly to the left. We begin to knead - on exhalation squeezing fingers and say "Uh". Widen your eyes - look like an owl. Turn your head slightly from side to side. Then we take the left hand by the right shoulder and do the same.
Breathing improves, tension goes away.
Exercise 5 "Lazy Eights"
We bend one arm at the elbow and put it forward, thumb up, on which we fix our eyes. Thumb hands on the midline of the body. Mentally imagine a circle in front of us, in which we draw an infinity sign - a lazy figure eight, the main thing is that it be round.
The left hand hangs freely along the body. With the right hand, calmly and freely draw: up along the midline of the body, to the left - down-right to the midline of the case and along it up to the middle and in the other direction: up-right-down-left-ser.line up.
We change hands. And draw with the left hand. Start left up.
Vision improves.
3. - Let's go to our laboratory. Sit down at the tables.
Before conducting experiments, listen to and remember the rules of the laboratory:
answer each other;
Do not interrupt each other;
Listen to the answers of a friend to the end;
Answer with a full sentence.
What's on your tables? (a cup of salt, a glass of water).
Repeat the safety rules!
Consider water. What is she?(liquid, transparent, odorless, shapeless, fresh, colorless).
Examine the substance in the cup. What is this? Riddle - hint: Separately, I'm not so tasty, but everyone needs food. (Salt.) What kind of salt? You can also try. (white, crystals).
Salt is the only mineral substance that people use in pure form. Salt is food product and we know how small crystals white color. In fact, salt of natural origin has a grayish tint. Salt is produced in different types: unpeeled (stone) and peeled (cooking), large and small, sea.
Where do we meet with salt? (in the kitchen, on the sea).
Right. In the sea, the ocean water is salty. In the world there are lakes with salt water, salt lakes, in which the water is even more salty than in the sea. Look. Here are the salt lakes.
4. - And now we are conducting an experiment. Pour the salt into the water. What happened? (salt dissolved)
What was the water like? (salty)
Where did the salt go? (she melted)
Is there any salt left in the water? (yes, the salt has changed its state)
And now the main question. Children, do you think it is possible to separate salt from water? Surely not? How?
(pour into another glass, filtering. Any assumption of children must be verified by experience)
5. Experiment - evaporation of salt on an alcohol lamp. What's left in the spoon? (salt)
The spoon is still hot, so I'll taste it myself - is it really salt? Yes, children, this is salt. So the assumption turned out to be correct: after heating, salt remained.
6. Well done! You have completed this task. Sequentially tell the stages of our experience.
I draw your attention to the fact that the process was reversible: first we mixed salt and water and got a solution, and then again we got salt and water from the solution.
Homework: What are the salt lakes in Russia, find their names.
How to get salt from sea water? For centuries, this question has baffled sailors wandering the seas and students alike wandering through science project fairs. The answer is simple: evaporation. When you make sea water evaporate ( naturally or artificially heating it), only water turns into steam, and salt remains. With this knowledge, it's pretty easy to separate the salt from the water with some simple materials you might already have at home.
Steps
How to do a basic water evaporation experiment
- Feel free to scrape some salt off the paper to season your food: it must be perfectly safe and edible. But be careful not to scrape off pieces of paper with it for your food!
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Start by boiling a pot of salt water. The simple experiment above shows how to extract salt from water, but what if you want less salty water as well? Distillation is the answer. Distillation is the process of heating water to separate it from other chemicals dissolved in it, then collecting the condensate, which must be relatively "clean". In this case, we'll start by making a few cups of salt water (read above how) and boiling them on the stove.
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Cover the bucket with a lid, but not completely. Next, find a lid for your ladle (it doesn't have to be a perfect fit). Lay the lid so that one part of it hangs from the ladle and is lower than all other parts. Watch as condensation begins to form on the lid and then drip from it.
- As the salt water boils, the water itself (without salt) will turn into steam and rise from the ladle. As it hits the lid, the steam will cool slightly and form liquid condensate (water) on the bottom of the lid. This water does not contain salt, so all that remains for us is to collect salt-free water.
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Let the water accumulate in the bowl. As the water runs downwards, condensation on the inside of the lid will naturally gather at its lowest point. Once enough of it has collected, it will begin to form into drops and fall down. Place a bowl under this point to catch drops of distilled water.
- If you like, you can lower a long, narrow metal or glass object (like a glass stirring rod or a thermometer) from the bottom of the lid into the bowl: then the water will run down it straight into the container.
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If necessary, repeat the previous step. The longer the water boils in the ladle, the more distilled water should collect in the bowl. This water will be devoid of most of the salt. However, in some cases a small amount of there will still be salt. Then you may need double distillation: Boiling water already collected in a bowl to remove salt residue.
- Technically, this water should be potable. However, if you are not sure that the lid of the ladle and the bowl for collecting water (and a metal or glass rod to drain it, if you used one) were clean, you should not drink it.
Heat water and add salt to it to get salt water. With this simple experiment, it's easy to see the principles of evaporation in action. To get started, you will need regular fine table salt, tap water, a frying pan, some black construction paper, and a stovetop. Pour a few cups of water into a frying pan and place it on a lit burner. Wait for the water to heat up: it doesn't have to boil, it's just that the hotter it is, the faster the salt will dissolve in it.
Add salt until it no longer dissolves. Continue to pour it on a teaspoon and stir. Eventually, you will reach the point where the water can no longer dissolve the salt, no matter how hot it is. It's called a line saturation water. Turn off the burner and let the water cool slightly.
Pour a tablespoon of water onto dark construction paper. Using a ladle or a tablespoon, pour some salt water onto a piece of dark construction paper. Place this piece on a plate ahead of time so you don't wet your work surface or table. All you have to do now is wait until the water evaporates. This process will be faster if the cardboard is left in sunlight.
Wait for the salt to form. As the water evaporates, it will leave behind miniature salt crystals. They should look like small shiny white or clear flakes on the surface of the cardboard. Congratulations! You have just separated the salt from the water.
How to make a distiller
Obtaining table salt from the Black Sea water and studying its properties (Author: Alexandra Borisenko, Novorossiysk Technical and Economic Lyceum, Krasnodar region. Head Kozlova N.P.)
For a long time, the inhabitants of the Kuban have been looking for an opportunity to obtain local salt due to the high cost of imported salt. The body of primitive man received the necessary salt with food of animal origin. Salt has had a strong influence on many human languages. More recently, salt was so expensive that wars were staged because of it, and sometimes a shortage of salt caused "salt riots." Now the problem of salt production in the Kuban has not been resolved, and I decided to study ways to obtain it.
Target: Obtaining table salt (NaCl) from the Black Sea water and the possibility of its use for residents of the Caucasian coast.
To achieve my goal, I set the following tasks:
1. To study the methods of extraction and properties of table salt.
2. To study the areas of use of table salt in human life.
3. Conduct an experiment to obtain sodium chloride from the water of the Black Sea and determine its salinity in the Tsemes Bay.
4. Estimate economic efficiency obtaining salt from sea water.
Methods: For the experiment, I used combined method ancient coast-dwellers successive freezing and evaporation.
Hypothesis: Table salt, obtained from the water of the Black Sea, has all the properties and qualities of commercially available salt.
Table salt has weak antiseptic properties; 10-15% salt content prevents the development of putrefactive bacteria, which leads to its widespread use as a preservative, and in the past in the processing of leather and fur raw materials. They used to say: “One eye on the police (where is the bread), the other on the salt cellar (salt shaker)”, “Without bread it’s not satisfying, without salt it’s not sweet.”
In nature, sodium chloride is found in dissolved form in sea water and in the form of the mineral halite - rock salt. The word "halite" comes from the Greek "galos", meaning both "salt" and "sea". Halite is rarely pure white. More often it is brownish or yellowish due to impurities of iron compounds.
In modern industry, salt is mined mainly three ways:
1. open way– development of salt layers coming to the surface (Artyomovskoye deposit)
2. Mine method - development of underground deposits (Iletsksol, Tyretsky salt mine, etc.)
3. Freezing or evaporation of salt from saline reservoirs (Baskunchak deposit, Lake Elton, etc.)
Store-bought salt is about 97% NaCl; the rest is accounted for by various natural impurities and special additives (iodides, carbonates, fluorides).
Container with pre-filtered sea water I placed it in the freezer, where it was kept at -18°C for 7 hours. The formed fresh ice after opening the plastic container was removed, and 120 g of the remaining liquid or brine was poured into a steel container. The brine was evaporated on a gas burner for 19 minutes. After evaporation, crystals formed on the entire bottom of the container in the form of an uneven, porous, brittle white crust. The size of the crystals ranges from 0.5 to 5 mm. Almost all of them do not have a regular shape, and only a few specimens approach the cube. When trying to separate from the crust, the crystals are destroyed, turning into White powder. The distribution of impurities of various salts in sea water can fluctuate under the influence of various factors within a wide range (accidental discharges of industrial enterprises, pesticide pollution, etc.).
Monetary costs in an experiment to determine salinity consist of payment for the consumption of electricity for work freezer and gas consumption. Electricity consumption according to the readings of the electric meter amounted to 4.7 kW / h. Due to the lack of a gas meter, the payment for the operation of a gas burner is assumed to be 0.7 rubles. The total costs for the evaporation of salts from sea water amounted to 4.7x1.97 + 0.7 = 9.96 rubles. The commercial cost of table salt in a retail network is 10 rubles. for 1 kg.
I studied the basic properties, methods of extraction and production of sodium chloride and conducted an experiment during which it turned out:
1. Salinity of sea water in laboratory and field conditions can be determined by the method of freezing and evaporation.
2. When using the technology of freezing and evaporation from sea water, sodium chloride with impurities of other salts in a mass volume of up to 20-25% is obtained in the final product.
Salt dissolution and evaporation
Target: Integration experimental - research activities within the framework of a single educational space for the development of educational areas by children. Increasing productive cooperation between the teacher and children.
Integration of educational areas.
Educational area "Cognitive development"
Continue to acquaint children with the properties of salt (smell, taste, color, solubility);
Develop a learning initiative
To form the ability and skills of research activities;
Exercise children in elementary experimentation with salt
Practice with loops
Educational area "Speech development"
To improve dialogical speech: to teach to participate in a conversation, it is clear for listeners to ask questions and answer them.
Develop curiosity. To expand children's ideas about objects and phenomena that did not take place in their own experience.
Educational area "Physical development"
Continue to introduce children to physical exercises to strengthen body systems (finger gymnastics for speech development); visual gymnastics - for the prevention of myopia).
Form the correct posture.
Material and equipment:
Magnifiers by the number of children, salt, water containers, (by the number of children, spoons, napkins, video slides on making salt.
Course progress.
- - Guys, I invite you to our laboratory again. We will be experimenting. But first, let's play.
Game "Say the other way around"
Game "Logic chain"
- - What is experience? (methods used by scientists in the study of science; scientific experiment).
Experience is a scientific experiment. To engage in science, one must be smart, be able to think, draw conclusions. And we want to be like that. To do this, we will conduct brain gymnastics.
Exercise 1
I.p. Standing feet shoulder width apart. We carry the shoulder to the hip, not the elbow to the knee! Head turns slightly as you move. The body seems to be folding, and the arms and legs are only substituted. Don't pinch your mouth. Lips are free.
This exercise increases the activity of a person and energizes him.
Exercise 2
We take ourselves by the ears - by the upper part of the ear: the thumb is behind, the index finger is in front. And gently massage the ears, as if stretching back and twisting a little. We massage several times from top to bottom each point on the edge of the auricle.
Clarity appears in the head, you can quickly collect your thoughts.
Exercise 3
We bend one arm at the elbow and put it forward, thumb up, on which we fix our eyes. The thumb is in the midline of the body. Mentally imagine a circle in front of us, in which we draw an infinity sign - a lazy figure eight, the main thing is that it be round.
The left hand hangs freely along the body. With the right hand, calmly and freely draw: up along the midline of the body, to the left - down-right to the midline of the case and along it up to the middle and in the other direction: up-right-down-left-ser.line up.
We change hands. And draw with the left hand. Start left up.
Vision improves.
3. - Let's go to our laboratory. Sit down at the tables.
Before conducting experiments, listen to and remember the rules of the laboratory:
answer each other;
Do not interrupt each other;
Listen to the answers of a friend to the end;
Answer with a full sentence.
What's on your tables? (a cup of salt, a glass of water).
Repeat the safety rules!
Consider water. What is she?(liquid, transparent, odorless, shapeless, fresh, colorless).
Examine the substance in the cup. What is this? Riddle - hint: Separately, I'm not so tasty, but everyone needs food. (Salt.) What kind of salt? You can also try. (white, crystals).
Salt is the only mineral that people consume in its pure form. Salt is a food product, and we know it as small white crystals. In fact, salt of natural origin has a grayish tint. Salt is produced in different forms: unrefined (stone) and refined (cooking), large and small, sea salt.
Where do we meet with salt? (in the kitchen, on the sea).
Right. In the sea, the ocean water is salty. In the world there are lakes with salt water, salt lakes, in which the water is even more salty than in the sea. Look. Here are the salt lakes.
4. - And now we are conducting an experiment. Pour the salt into the water. What happened? (salt dissolved)
What was the water like? (salty)
Where did the salt go? (she melted)
Is there any salt left in the water? (yes, the salt has changed its state)
And now the main question. Children, do you think it is possible to separate salt from water? Surely not? How?
(pour into another glass, filtering. Any assumption of children must be verified by experience)
5. Experiment - evaporation of salt in a spoon.
What's left in the spoon? (salt)
The spoon is still hot, so I'll taste it myself - is it really salt? Yes, children, this is salt. So, the assumption turned out to be correct: after heating, salt remained.
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