Question 1. Sucrose. Its structure, properties, production and application.
Answer. It has been experimentally proven that the molecular form of sucrose
- C 12 H 22 O 11. The molecule contains hydroxyl groups and consists of interconnected residues of glucose and fructose molecules.
Physical properties
Pure sucrose is a colorless crystalline substance with a sweet taste, highly soluble in water.
Chemical properties:
1. Subject to hydrolysis:
C 12 H 22 O 11 + H2O C 6 H 12 O 6 + C 6 H 12 O 6
2. Sucrose is a non-reducing sugar. It does not give a “silver mirror” reaction, and interacts with copper (II) hydroxide as a polyhydric alcohol, without reducing Cu (II) to Cu (I).
Being in nature
Sucrose is a part of sugar beet juice (16-20%) and sugar cane (14-26%). In small quantities, it is found together with glucose in the fruits and leaves of many green plants.
Receipt:
1. Sugar beet or sugar cane is turned into fine shavings and placed in diffusers through which hot water is passed.
2. The resulting solution is treated with milk of lime, a soluble calcium saccharate of alcoholates is formed.
3. To decompose calcium sucrose and neutralize excess calcium hydroxide, carbon monoxide (IV) is passed through the solution:
C 12 H 22 O 11 CaO 2H 2 + CO 2 = C 12 H 22 O 11 + CaCO 3 + 2H 2 O
4. The solution obtained after precipitation of calcium carbonate is filtered and then evaporated in vacuum apparatus and sugar crystals are separated by centrifugation.
5. Isolated granulated sugar usually has a yellowish color, as it contains coloring matter. To separate them, sucrose is dissolved in water and passed through activated charcoal.
Application:
Sucrose is mainly used as a food product and in the confectionery industry. By hydrolysis, artificial honey is obtained from it.
Question 2. Features of the placement of electrons in atoms of elements of small and large periods. States of electrons in atoms.
Answer. An atom is a chemically indivisible, electrically neutral particle of matter. An atom consists of a nucleus and electrons moving in certain orbits around it. An atomic orbital is the region of space around the nucleus within which an electron is most likely to be found. Orbitals are also called electron clouds. Each orbital corresponds to a certain energy, as well as the shape and size of the electron cloud. A group of orbitals for which the energy values are close is assigned to the same energy level. An energy level cannot contain more than 2n 2 electrons, where n is the number of the level.
Types of electron clouds: spherical - s-electrons, one orbital at each energy level; dumbbell-shaped - p-electrons, three orbitals p x, p y, p z; in the form resembling two crossed dumbbells, - d-electrons, five orbitals d xy, d xz, d yz, d 2 z, d 2 x - d 2 y.
The distribution of electrons over energy levels reflects the electronic configuration of the element.
Rules for filling energy levels with electrons and
sublevels.
1. The filling of each level begins with s-electrons, then the p-, d- and f-energy levels are filled with electrons.
2. The number of electrons in an atom is equal to its serial number.
3. The number of energy levels corresponds to the number of the period in which the element is located.
4. The maximum number of electrons in the energy level is determined by the formula
Where n is the level number.
5. The total number of electrons in atomic orbitals of the same energy level.
For example, aluminum, the nuclear charge is +13
Distribution of electrons by energy levels - 2,8,3.
Electronic configuration
13 Al:1s 2 2s 2 2p 6 3s 2 3p 1 .
In the atoms of some elements, the phenomenon of electron slippage is observed.
For example, in chromium, electrons jump from the 4s sublevel to the 3d sublevel:
24 Cr 1s 2 2s 2 2p 6 3s 2 3d 5 3d 5 4s 1 .
The electron moves from the 4s sublevel to the 3d one, because the 3d 5 and 3d 10 configurations are more energetically favorable. An electron occupies a position in which its energy is minimal.
The energy f-sublevel is filled with electrons in the element 57La -71 Lu.
Question 3. Recognize substances KOH, HNO 3, K 2 CO 3.
Answer: KOH + phenolphthalene → crimson color of the solution;
NHO 3 + litmus → red color of the solution,
K 2 CO 3 + H 2 SO 4 \u003d K 2 SO 4 + H 2 0 + CO 2
Ticket number 20
Question 1 . Genetic relationship of organic compounds of various classes.
Answer: Scheme of the chain of chemical transformations:
C 2 H 2 → C 2 H 4 → C 2 H 6 → C 2 H 5 Cl → C 2 H 5 OH → CH 3 CHO → CH 3 COOH
C 6 H 6 C 2 H 5 OH CH 2 \u003d CH-CH \u003d CH 2 CH 3 COOC 2 H 5
C 6 H 5 Cl CH 3 O-C 2 H 5 C 4 H 10
C 2 H 2 + H 2 \u003d C 2 H 4,
alkyne alkene
C 2 H 4 + H 2 \u003d C 2 H 6,
alkene alkane
C 2 H 6 + Cl 2 \u003d C 2 H 5 Cl + HCl,
C 2 H 5 Cl + NaOH \u003d C 2 H 5 OH + NaCl,
chloralkane alcohol
C 2 H 5 OH + 1/2O 2 CH 3 CHO + H 2 O,
alcohol aldehyde
CH 3 CHO + 2Cu(OH) 2 = CH 3 COOH + 2CuOH + H 2 O,
C 2 H 4 + H 2 O C 2 H 5 OH,
alkene alcohol
C 2 H 5 OH + CH 3 OH \u003d CH 3 O-C 2 H 5 + H 2 O,
alcohol alcohol ether
3C 2 H 2 C 6 H 6,
alkyne arena
C 6 H 6 + Cl 2 \u003d C 6 H 5 Cl + HCl,
C 6 H 5 Cl + NaOH \u003d C 6 H 5 OH + NaCl,
C 6 H 5 OH + 3Br 2 \u003d C 6 H 2 Br 3 OH + 3HBr;
2С 2 H 5 OH \u003d CH 2 \u003d CH-CH \u003d CH 2 + 2H 2 O + H 2,
diene alcohol
CH 2 \u003d CH-CH \u003d CH 2 + 2H 2 \u003d C 4 H 10.
diene alkane
Alkanes are hydrocarbons with the general formula C n H 2 n +2 that do not add hydrogen and other elements.
Alkenes are hydrocarbons with the general formula C n H 2 n, in the molecules of which there is one double bond between carbon atoms.
Diene hydrocarbons include organic compounds with the general formula C n H 2 n -2, in the molecules of which there are two double bonds.
Hydrocarbons with the general formula C n H 2 n -2, in the molecules of which there is one triple bond, belong to the acetylene series and are called alkynes.
Compounds of carbon with hydrogen, in the molecules of which there is a benzene ring, are classified as aromatic hydrocarbons.
Alcohols are hydrocarbon derivatives in which one or more hydrogen atoms are replaced by hydroxyl groups.
Phenols include derivatives of aromatic hydrocarbons, in the molecules of which the hydroxyl groups are bonded to the benzene ring.
Aldehydes - organic substances containing a functional group - CHO (aldehyde group).
Carboxylic acids are organic substances whose molecules contain one or more carboxyl groups connected to a hydrocarbon radical or a hydrogen atom.
Esters include organic substances that are formed in the reactions of acids with alcohols and contain a group of atoms C (O) -O -C.
Question 2. Types of crystal lattices. Characterization of substances with different types of crystal lattices.
Answer. The crystal lattice is a spatial, ordered by the mutual arrangement of particles of matter, which has an unambiguous, recognizable motif.
Depending on the type of particles located at the lattice sites, there are: ionic (IR), atomic (AKR), molecular (MKR), metallic (Met. CR), crystal lattices.
MKR - at the nodes there is a molecule. Examples: ice, hydrogen sulfide, ammonia, oxygen, nitrogen in the solid state. The forces acting between molecules are relatively weak; therefore, substances have low hardness, low boiling and melting points, and poor solubility in water. Under normal conditions, these are gases or liquids (nitrogen, hydrogen peroxide, solid CO 2). Substances with MCR are dielectrics.
ACR - atoms in knots. Examples: boron, carbon (diamond), silicon, germanium. Atoms are connected by strong covalent bonds, so substances are characterized by high boiling and melting points, high strength and hardness. Most of these substances are insoluble in water.
IFR - at the sites of cations and anions. Examples: NaCl, KF, LiBr. This type of lattice is present in compounds with an ionic type of bond (metal-nonmetal). Substances are refractory, low volatile, relatively strong, good conductors of electric current, highly soluble in water.
Met. CR is a lattice of substances consisting only of metal atoms. Examples: Na, K, Al, Zn, Pb, etc. The aggregate state is solid, insoluble in water. In addition to alkali and alkaline earth metals, conductors of electric current, boiling and melting temperatures range from medium to very high.
Question 3. Task. To burn 70 g of sulfur, 30 liters of oxygen were taken. Determine the volume and quantity of substance formed sulfur dioxide.
Given: Find:
m(S) = 70 d, V(SO2) = ?
V (O 2) \u003d 30 l. v(SO2) = ?
Decision:
m=70 G V= 30 l x l
S + O 2 \u003d SO 2.
v: 1 mol 1 mol 1 mol
M: 32 g/mol -- --
V: -- 22.4L 22.4L
V(O 2) theor. \u003d 70 * 22.4 / 32 \u003d 49 l (O 2 is in short supply, calculation for it).
Since V (SO 2) \u003d V (O 2), then V (SO 2) \u003d 30 liters.
v (SO 2) \u003d 30 / 22.4 \u003d 1.34 mol.
Answer. V (SO 2) \u003d 30 l, v \u003d 1.34 mol.
Physical properties
Pure sucrose is a colorless crystalline substance with a sweet taste, highly soluble in water.
Chemical properties
The main property of disaccharides, which distinguishes them from monosaccharides, is the ability to hydrolyze in an acidic environment (or under the action of enzymes in the body):
C 12 H 22 O 11 + H2O> C 6 H 12 O 6 + C 6 H 12 O 6
Sucrose glucose fructose
Glucose formed during hydrolysis can be detected by the "silver mirror" reaction or by its interaction with copper (II) hydroxide.
Obtaining sucrose
Sucrose C 12 H 22 O 11 (sugar) is obtained mainly from sugar beet and sugar cane. In the production of sucrose, chemical transformations do not occur, because it is already present in natural products. It is only isolated from these products as pure as possible.
The process of isolating sucrose from sugar beets:
Peeled sugar beets in mechanical beet cutters are turned into thin chips and placed in special vessels - diffusers through which hot water is passed. As a result, almost all sucrose is washed out of the beets, but with it various acids, proteins and coloring substances pass into the solution, which must be separated from sucrose.
The solution formed in the diffusers is treated with milk of lime.
C 12 H 22 O 11 + Ca(OH) 2 > C 12 H 22 O 11 2CaO H 2 O
Calcium hydroxide reacts with the acids contained in the solution. Since the calcium salts of most organic acids are sparingly soluble, they precipitate. Sucrose, on the other hand, with calcium hydroxide forms a soluble sucrose of the alcoholate type - C 12 H 22 O 11 2 CaO H 2 O
3. To decompose the resulting calcium sucrose and neutralize the excess of calcium hydroxide, carbon monoxide (IV) is passed through their solution. As a result, calcium is precipitated in the form of carbonate:
C 12 H 22 O 11 2CaO H 2 O + 2CO 2 > C 12 H 22 O 11 + 2CaCO 3 v 2H 2 O
4. The solution obtained after precipitation of calcium carbonate is filtered, then evaporated in vacuum apparatus and sugar crystals are separated by centrifugation.
However, it is not possible to isolate all the sugar from the solution. A brown solution (molasses) remains, which contains up to 50% sucrose. Molasses is used to produce citric acid and some other products.
5. Isolated granulated sugar usually has a yellowish color, as it contains coloring matter. To separate them, sucrose is redissolved in water and the resulting solution is passed through activated charcoal. Then the solution is again evaporated and subjected to crystallization. (see annex 2)
Application of sucrose
Sucrose is mainly used as a food product and in the confectionery industry. By hydrolysis, artificial honey is obtained from it.
Being in nature and the human body
Sucrose is a component of sugar beet juice (16-20%) and sugar cane (14-26%). In small quantities, it is found together with glucose in the fruits and leaves of many green plants.
It is useful to know the chemical formulas of substances common in everyday life not only as part of a school chemistry course, but simply for general erudition. Almost everyone knows the formula for water or table salt, but few can immediately get to the point about alcohol, sugar or vinegar. Let's go from simple to complex.
What is the formula for water?
This liquid, thanks to which amazing wildlife appeared on planet Earth, is known and drunk by everyone. Moreover, it makes up about 70% of our body. Water is the simplest combination of an oxygen atom with two hydrogen atoms.
Chemical formula of water: H 2 O
What is the formula for table salt?
Table salt is not only an indispensable culinary dish, but also one of the main components of sea salt, the reserves of which in the World Ocean amount to millions of tons. The formula for common salt is simple and easy to remember: 1 sodium atom and 1 chlorine atom.
Chemical formula of table salt: NaCl
What is the formula for sugar?
Sugar is a white crystalline powder, without which no sweet tooth in the world can live a day. Sugar is a complex organic compound whose formula is hard to remember: 12 carbon atoms, 22 hydrogen atoms and 11 oxygen atoms form a sweet and complex structure.
Chemical formula of sugar: C 12 H 22 O 11
What is the formula for vinegar?
Vinegar is a solution of acetic acid, which is used for food, as well as for cleaning metals from plaque. The acetic acid molecule has a complex structure consisting of two carbon atoms, to one of which three hydrogen atoms are attached, and to the other two oxygen atoms, one of which has taken another hydrogen.
Chemical formula of acetic acid: CH 3 COOH
What is the formula for alcohol?
Let's start with the fact that alcohols are different. The alcohol that is used to make wines, vodkas and cognacs is scientifically called ethanol. In addition to ethanol, there are still a bunch of alcohols that are used in medicine, automotive and aviation.
Chemical formula of ethanol: C 2 H 5 OH
What is the formula for baking soda?
Baking soda is scientifically called sodium bicarbonate. From this name, any novice chemist will understand that the soda molecule contains sodium, carbon, oxygen and hydrogen.
Chemical formula of baking soda: NaHCO 3
Today is February 24, 2019. Do you know what holiday is today?
Tell What is the formula for sugar, salt, water, alcohol, vinegar and other substances friends on social networks:
sucrose C 12 H 22 O 11, or beet sugar, cane sugar, in everyday life just sugar - a disaccharide from the group of oligosaccharides, consisting of two monosaccharides - α-glucose and β-fructose.
Chemical properties of sucrose
An important chemical property of sucrose is the ability to undergo hydrolysis (when heated in the presence of hydrogen ions).
Since the bond between monosaccharide residues in sucrose is formed by both glycosidic hydroxyls, it does not have restorative properties and does not give a "silver mirror" reaction. Sucrose retains the properties of polyhydric alcohols: it forms water-soluble sugars with metal hydroxides, in particular, with calcium hydroxide. This reaction is used to isolate and purify sucrose in sugar refineries, which we will talk about a little later.
When an aqueous solution of sucrose is heated in the presence of strong acids or under the action of an enzyme invertases going on hydrolysis of this disaccharide to form a mixture of equal amounts of glucose and fructose. This reaction is the reverse of the formation of sucrose from monosaccharides:
The resulting mixture is called invert sugar and is used for the production of caramel, sweetening food products, to prevent the crystallization of sucrose, obtaining artificial honey, and the production of polyhydric alcohols.
Relation to hydrolysis
The hydrolysis of sucrose is easy to follow with a polarimeter, since the sucrose solution has right-hand rotation, and the resulting mixture D- glucose and D- fructose has a left rotation, due to the prevailing value of the left rotation of D-fructose. Consequently, as sucrose is hydrolyzed, the angle of right rotation gradually decreases, passes through zero, and at the end of hydrolysis, a solution containing equal amounts of glucose and fructose acquires a stable left rotation. In this regard, hydrolyzed sucrose (a mixture of glucose and fructose) is called invert sugar, and the hydrolysis process itself is called inversion (from Latin inversia - turning, rearranging).
The structure of maltose and celobiose. Relation to hydrolysis
Maltose and starch. Composition, structure and properties. Relation to hydrolysis
Physical properties
Maltose is easily soluble in water and has a sweet taste. The molecular weight of maltose is 342.32. The melting point of maltose is 108 (anhydrous).
Chemical properties
Maltose is a reducing sugar because it has an unsubstituted hemiacetal hydroxyl group.
By boiling maltose with dilute acid and by the action of an enzyme maltose hydrolyzes (two molecules of glucose C 6 H 12 O 6 are formed).
Starch (C 6 H 10 O 5) n polysaccharides of amylose and amylopectin, the monomer of which is alpha-glucose. Starch, synthesized by different plants in chloroplasts, under the action of light during photosynthesis, differs somewhat in the structure of grains, the degree of polymerization of molecules, the structure of polymer chains, and physicochemical properties.
An example of the most common disaccharides in nature (oligosaccharide) is sucrose(beet or cane sugar).
Oligosaccharides are the condensation products of two or more monosaccharide molecules.
disaccharides - These are carbohydrates that, when heated with water in the presence of mineral acids or under the influence of enzymes, undergo hydrolysis, splitting into two molecules of monosaccharides.
Physical properties and being in nature
1. It is a colorless crystals of sweet taste, highly soluble in water.
2. The melting point of sucrose is 160 °C.
3. When molten sucrose solidifies, an amorphous transparent mass is formed - caramel.
4. Contained in many plants: birch sap, maple, carrots, melons, as well as sugar beet and sugar cane.
Structure and chemical properties
1. The molecular formula of sucrose is C 12 H 22 O 11
2. Sucrose has a more complex structure than glucose. The sucrose molecule consists of glucose and fructose residues connected to each other through the interaction of hemiacetal hydroxyls (1→2)-glycosidic bond:
3. The presence of hydroxyl groups in the sucrose molecule is easily confirmed by the reaction with metal hydroxides.
If a solution of sucrose is added to copper (II) hydroxide, a bright blue solution of copper sucrose is formed (qualitative reaction of polyhydric alcohols).
Video experiment "Proof of the presence of hydroxyl groups in sucrose"
4. There is no aldehyde group in sucrose: when heated with an ammonia solution of silver (I) oxide, it does not give a “silver mirror”, when heated with copper (II) hydroxide, it does not form red copper (I) oxide.
5. Sucrose, unlike glucose, is not an aldehyde. Sucrose, being in solution, does not enter into the "silver mirror" reaction, since it is not able to turn into an open form containing an aldehyde group. Such disaccharides are not capable of being oxidized (i.e., being reducing agents) and are called non-reducing sugars.
Video experience "Lack of reducing ability of sucrose"
6. Sucrose is the most important of the disaccharides.
7. It is obtained from sugar beet (it contains up to 28% of sucrose from dry matter) or from sugar cane.
Reaction of sucrose with water.
An important chemical property of sucrose is the ability to undergo hydrolysis (when heated in the presence of hydrogen ions). In this case, from one sucrose molecule, a glucose molecule and a fructose molecule are formed:
C 12 H 22 O 11 + H 2 O t , H 2 SO 4 → C 6 H 12 O 6 + C 6 H 12 O 6
Video experience "Acid hydrolysis of sucrose"
Among the isomers of sucrose having the molecular formula C 12 H 22 O 11, maltose and lactose can be distinguished.
During hydrolysis, various disaccharides are split into their constituent monosaccharides by breaking the bonds between them ( glycosidic bonds):
Thus, the hydrolysis reaction of disaccharides is the reverse of the process of their formation from monosaccharides.
Application of sucrose
· Food product;
· In the confectionery industry;
Obtaining artificial honey
