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Separating salt from sand is an interesting experiment that can be done at home. If you have ever thought about the scientific idea of solubility, then the separation of these substances from each other will serve as a clear example of this concept. This process is so simple that you will get the opportunity to see the laws of physics in action both at school and at home.
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the sedimentation method can be used to separate sand and salt, for this we pour the mixture into water and stir, the salt dissolves in water and the sand settles. But it will be safer to separate the river sand from the salt solution using the filtering method, it can be done using a paper filter and a funnel. In this case, the salt solution will pass through the paper filter, and the sand will settle on it, sand in this case is the precipitate, and the salt solution will be the filtrate. Salt can be separated from the filtrate using the evaporation method. To do this, this mixture is heated, the water evaporates, and the salt remains on the walls of the porcelain cup. Salt can also be isolated from the filtrate by evaporation, i.e. partial evaporation of the liquid - in this case a more concentrated solution is obtained, which upon cooling gives a precipitate in the form of salt (in this case, the crystallization method is used)
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This lesson is a practical lesson in the process of which you will learn how to separate different mixtures of substances using the methods you have learned. The lesson describes in detail the experiments on the separation of the following mixtures: 1) sugar with sawdust, 2) salt with river sand, 3) vegetable oil with water.
Subject: Initial Chemical Concepts
Lesson: Practice 2. Separation of Mixtures of Substances
1. Separation of a mixture of sugar and sawdust
The separation of any mixture of substances is based on knowledge of the differences in the properties of its constituent components. Thus, in order to divide the proposed mixture into constituent components, you need to know how they differ from each other.
EXPERIENCE 1. Separation of a mixture of sugar and sawdust. As you know, sugar dissolves well in water, but sawdust does not. In addition, sawdust does not drown in water, so the sedimentation method can be used to separate this mixture.
First, the mixture must be placed in water (sugar will dissolve), and then carefully remove the wood chips from the surface of the water. In order to isolate the pure sugar dissolved in water, you need to evaporate the solution, leaving a little water, and then cool it - as a result, sugar crystals will precipitate (here evaporation and crystallization methods are used).
Fig. 1. Separation of a mixture of sugar and sawdust
2. Cleaning salt from river sand
EXPERIENCE 2. Cleaning salt from the admixture of river sand. Easily soluble substances can be easily cleaned from mechanical impurities by filtering the solution. First, it is necessary to place the contaminated table salt in water, the salt will dissolve in water, but no impurities. To separate solids, you can use the filtering method. Note that when a contaminant is soluble, the filter cannot separate it. How to get dry table salt from a purified solution? To do this, you need to use the evaporation method: the water will evaporate, and crystals of purified salt will remain on the walls of the porcelain cup.
Fig. 2. Purification of table salt from river sand impurities (stage of evaporation of the filtrate)
Purification of salt from river sand is carried out based on such properties of salt as good solubility in water and non-volatility (when evaporating water from a solution).
3. Separation of a mixture of vegetable oil and water
EXPERIENCE 3. Separation of a mixture of vegetable oil and water. If liquids are not soluble in each other and have different densities, then they can be separated using the settling method.
Pour water into the separatory funnel and add a few drops of vegetable oil. Shake the funnel. It turns out a white emulsion: a mixture of oil and water. Let the mixture stand. Gradually, the emulsion is divided into two layers: the heavy lower layer is water. Upper, lighter - vegetable oil. Carefully pour water through the tap of the separatory funnel. Vegetable oil remains in the funnel.
Fig. 3. Using the settling method to separate a mixture of vegetable oil and water
By settling, it is possible to separate mixtures of other slightly or insoluble liquids of different densities in each other. For example, a mixture of gasoline and water, a mixture of oil and water.
Recommended Reading List
1. A collection of tasks and exercises in chemistry: 8th grade: to the textbook P.A. Orzhekovsky and others. "Chemistry, Grade 8" / P.A. Orzhekovsky, N.A. Titov, F.F. Hegel. - M .: AST: Astrel, 2006.
2. Ushakova OV Workbook on chemistry: 8th grade: to the textbook P.A. Orzhekovsky and others. "Chemistry. Grade 8 ”/ O.V. Ushakova, P.I. Bespalov, P.A. Orzhekovsky, under. ed. prof. P.A. Orzhekovsky - M .: AST: Astrel: Profizdat, 2006. (p.10-11)
3. Chemistry: 8th grade: textbook. for general institutions / P.A. Orzhekovsky, L.M. Meshcheryakova, L.S. Contact M .: AST: Astrel, 2005. (§4)
4. Chemistry: inorg. chemistry: textbook. for 8 cl. general institutions / G.E. Rudzitis, FyuGyu Feldman. - M .: Education, Moscow Textbooks OJSC, 2009. (§2)
5. Encyclopedia for children. Volume 17. Chemistry / Chap. ed.V.A. Volodin, Ved. scientific ed. I. Leenson. - M .: Avanta +, 2003.
Additional web resources
1. A single collection of digital educational resources (Source).
2. The electronic version of the journal "Chemistry and Life" (Source).
Do a home experiment. Touch up 50 ml of water with ink. Add 2-3 tablets of activated carbon. Mix well. Let the mixture settle or filter it. Describe your observations. What water treatment method did you use?
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