A dispersed mass has a dispersive system of particles <1nm (10-9m) in diameter. Dispersions are molecules or ions with macroscopic characteristics of transparency, homogeneity, and stability.
Solution is the dispersion of one or more substances into another, forming a homogeneous, stable mixture. In this case, the solute is equivalent to the dispersant and the solvent is equivalent to the dispersant. Common solutions in life are sucrose solution, iodine, clarified lime water, dilute hydrochloric acid, salt water, air, etc.
Classified according to the different states of aggregation:
Gaseous solutions: gas mixtures, referred to as gases (such as air).
Liquid solution: dissolution or liquid-liquid dissolution of a gas or solid in a liquid state, referred to as a solution (e.g., brine).
Solid solution: a mixture of solids that are molecularly dispersed from each other, referred to as a solid solution (e.g., alloy).
Reading: generally read as "so-and-so (solute) of a (solvent) solution", such as alcohol can be read as "an aqueous solution of ethanol"
[edit]Second, the composition of the solution:
1. solute: the dissolved Substance
2. solvent: its dissolving effect of the substance
3. two liquids dissolve each other when dissolved, generally the amount of a more called the solvent, a lesser amount of a solute.
4. two liquids dissolve when dissolved, if one of them is water, the water is generally called the capacitor.
Of these, water (H2O) is the most commonly used solvent and can dissolve many substances. Gasoline and alcohol are also commonly used solvents, such as gasoline can dissolve fats and oils, alcohol can dissolve iodine and so on.
Solutes can be solids, liquids or gases; if two liquids dissolve each other, the one with the larger amount is generally called the solvent, and the one with the smaller amount is called the solute.
[edit]Third, the nature of the solution:
1. homogeneity: the composition and nature of the solution is exactly the same everywhere;
2. stability: the temperature is constant, the amount of solvent is the same, the solute and solvent will not be separated for a long time.
3. Transparency: is due to the individual molecules or ions of the solute is very small (diameter less than 1nm0, and thus can not block the transmission of light. Transparent solution does not mean that the solution is colorless, for example, ferrous sulfate solution is light green.
4 (liquid). Can pass through filter paper: the solute particles in the solution are less than 1 nm in diameter and can pass through the filter paper.
[edit]IV. Classification of solutions:
Saturated solution: at a certain temperature, a certain amount of solvent, the solute can not continue to dissolve the solution.
Unsaturated solution: at a certain temperature, a certain amount of solvent, the solute can continue to dissolve the solution.
Supersaturated solution: at a certain temperature, a certain amount of solvent, the solute can not continue to dissolve and has been part of the solute precipitation. Can be made by adding solvent or filtering, so that the supersaturated solution into a saturated solution.
Saturated and unsaturated solution conversion:
Unsaturated solution can be converted to saturated solution by adding solute (for all solutions) or lowering the temperature (for most of the solutes whose solubility rises with temperature, and vice versa, such as lime water), and by evaporating the solvent (when the solvent is liquid).
A saturated solution can be converted to an unsaturated solution by adding solvent (which is true for all solutions) or by increasing temperature (which is true for most solutes whose solubility increases with temperature, and vice versa, e.g., lime water).
[edit]V. Concepts, calculations and preparation of solutions
Related concepts
Solubility: at a certain temperature, a solid substance in 100g of solvent saturated by the mass of dissolved. If the solvent is not specified, the general term solubility refers to the solubility of a substance in water.
The solubility of a gas is the volume of a gas dissolved in 1 volume of water to saturation at a pressure of 101 kPa and a certain temperature.
Calculations
Mass of solution = Mass of solute + Mass of solvent
But volume of solution < Volume of solute + Volume of solvent
Mass fraction of solute = Mass of solute/Mass of solution × 100%
Mass of solute = Mass of solution × Mass fraction of solute
Preparation
In the laboratory. General steps in preparing a solution:
1. By mass fraction of solute: calculate, weigh, measure, dissolve, bottle and label.
2. By concentration of substance: calculate, weigh, dissolve, (cool), pipette, wash, set volume, shake well.
[edit]VI. Uses of solutions
Chemical reactions carried out in solutions are usually relatively fast. Therefore, in the laboratory or in chemical production, to make two solids that can react, often dissolve them first, and then mix the two solutions and shaking or stirring to speed up the reaction.
Solutions also have a great significance for the physiological activities of plants and animals. Animals ingest nutrients from food that must be digested and turned into solution before they can be absorbed. In animals oxygen and carbon dioxide are also dissolved in the blood for circulation. In the medical use of glucose solution and saline, treatment of bacterial infections caused by a variety of inflammatory injections (such as gentamicin, kanamycin), a variety of eye drops, etc., are in accordance with certain requirements for the use of the solution. Plants from the soil to obtain a variety of nutrients, but also to become a solution, in order to be absorbed by the roots. Soil contains water, which dissolves a variety of substances, forming a soil solution, the soil solution contains the nutrients needed by plants. Many fertilizers, such as human urine, cow and horse manure, crop stalks, weeds, etc., before application are subjected to the process of decomposition, one of the purposes is to make the complex insoluble organic matter into a simple soluble substances, which can be dissolved in the soil solution for the crops to absorb.
[edit]VII, the formation of solutions
The process of solution formation is accompanied by energy, volume changes, and sometimes color changes. Dissolution is a special physicochemical change divided into two processes. One is the dissociation of solute molecules or ions, this process requires the absorption of heat to overcome the intermolecular attraction, while increasing the volume; the second is the combination of solvent molecules and solute molecules, which is an exothermic process at the same time the volume is reduced. The combination of the whole process is the **** same action of both.
VIII, the dilution of solutions
According to the total amount of solute before and after the dilution of the same operation, either with water, or with a dilute solution to dilute a concentrated solution, can be calculated.
(1) dilution of concentrated solutions with water
Set the mass of the concentrated solution before dilution is m, the mass fraction of its solute is a%, the mass of water added to the dilution is n, the mass fraction of solute after dilution is b%.
Then we can get m × a% = (m + n) × b%
(2) Dilute the concentrated solution with the dilute solution
Set the mass of the concentrated solution to be A, and the mass fraction of its solute to be a%, and the mass of the dilute solution to be B, and the mass fraction of its solute to be b%, and the mass fraction of solute after mixing of the two liquids to be c%.
Then we get A × a% + B × b% = (A + B) × c% (1)
or A/B = (c%-b%)/(a%-c%) (2)
1. The solubility of a solid is the number of grams dissolved when a substance is saturated in 100 grams of solvent at a certain temperature. When the number of grams dissolved, expressed in the letter s, its unit is "g/100g of water". In the case of unspecified, usually solubility refers to the solubility of the substance in water.
2, the solubility of a gas usually refers to the gas (the pressure of 1 standard atmospheric pressure) at a certain temperature in a volume of water dissolved in a volume of water. Also commonly used "g/100g water" as a unit (naturally, also available in volume).
3, solubility is a certain temperature, a substance in 100 grams of solvent (usually water) in the saturated state of the number of grams dissolved.
4, special attention: the unit of solubility is grams (or grams / 100 grams of water) rather than no unit
[edit paragraph] solubility factors
Substance dissolved or not, the magnitude of the ability to dissolve, on the one hand, is determined by the nature of the substance (referring to the solvent and the solute); on the other hand, also with the outside world conditions, such as temperature, pressure, the type of solvent and so on. On the other hand, it is also related to external conditions such as temperature, pressure, and type of solvent. Under the same conditions, some substances are easy to dissolve, while some substances are difficult to dissolve, that is, different substances in the same solvent with different solvency. Usually the ability of a substance to dissolve in another substance is called solubility. For example, sugar is soluble in water, while fats and oils are insoluble in water, that is, their solubility in water is different. Solubility is a quantitative representation of solubility.
The solubility of a solid substance is the number of grams of a substance dissolved in 100 grams of solvent when saturated at a given temperature. When not specified, solubility usually refers to the solubility of the substance in water. For example, at 20°C, the solubility of table salt is 36 grams and the solubility of potassium chloride is 34 grams. These data can show that at 20 ℃, the maximum solubility of table salt and potassium chloride in 100 grams of water is 36 grams and 34 grams, respectively; it also shows that at this temperature, table salt is more soluble than potassium chloride in water.
Usually, at room temperature (20 degrees), the solubility of 10g/100g of water is called soluble substance, the solubility of 1~10g/100g of water is called soluble substance, the solubility of 0.01g~1g/100g of water is called slightly soluble substance, and the solubility of less than 0.01g/100g of water is called difficult to dissolve substance. It can be seen that the dissolution is absolute, insoluble is relative.
The solubility of gases is also related to pressure. The greater the pressure, the greater the solubility, and vice versa.
The higher the temperature, the less soluble the gas.
[edit]Solubility of solids
Most solids increase in solubility with increasing temperature, such as potassium nitrate
A few solubility of solids are not much affected by temperature, such as table salt (sodium chloride)
Very few solubility of substances decreases with increasing temperature, such as calcium hydroxide. Because calcium hydroxide has two hydrates [Ca(OH)2-2H2O and Ca(OH)2-12H2O]. These two hydrates are more soluble and anhydrous calcium hydroxide is very soluble. As the temperature rises, these crystalline hydrates gradually change into anhydrous calcium hydroxide, so the solubility of calcium hydroxide decreases as the temperature rises.
[edit]Gas solubility
At a certain temperature and pressure, the maximum amount of gas dissolved in a certain amount of solvent is called the solubility of the gas. Commonly used at a fixed temperature in 1 volume of solvent dissolved in the most volume number to indicate. Such as 20 ℃ when 100mL water can dissolve 1.82mL hydrogen, is expressed as 1.82mL/100mL water. The solubility of the gas in addition to the nature of the gas, the nature of the solvent, but also with the temperature, pressure, and its solubility generally with the temperature increases and decreases, due to the dissolution of gases when the volume change is very large, so its solubility with the increase in pressure and a significant increase. On the solubility of gases dissolved in liquids, in 1803 the British chemist W. Henry, based on the study of dilute solutions summarized a law called Henry's law.
Solubility of some gases at 101kPa atmospheric pressure
One of the solubilities of gases
The maximum amount of a gas that can be dissolved in a given amount of solvent at a given temperature and pressure is called the solubility of the gas. Commonly used at a fixed temperature in 1 volume of solvent dissolved in the most volume number to indicate. Such as 20 ℃ when 100mL water can dissolve 1.82mL hydrogen, is expressed as 1.82mL/100mL water. The solubility of the gas in addition to the nature of the gas, the nature of the solvent, but also with the temperature, pressure, and its solubility generally with the temperature increases and decreases, due to the dissolution of the gas when the volume change is very large, so its solubility with the increase in pressure and a significant increase. On the solubility of gases dissolved in liquids, in 1803 the British chemist W. Henry, based on the study of dilute solutions summarized a law called Henry's law.
Solubility of some gases at 101kPa atmospheric pressure
Solubility of gases bis
The size of the solubility of a gas is determined by the nature of the gas in the first place, but also with the pressure of the gas and the solvent of the temperature of the gas and the different changes. For example, at 20 ℃, the pressure of the gas is 1.013 × 10 ^ 5 Pa, a liter of water can dissolve the volume of the gas is: ammonia is 702 L, hydrogen is 0.01819 L, oxygen is 0.03102 L. Ammonia is soluble in water because ammonia is a polar molecule, water is also a polar molecule, and ammonia molecules with water molecules can also form hydrogen bonding, the occurrence of significant hydration, therefore, it is very soluble; while ammonia is a polar molecule, water is also polar molecules, and ammonia molecules with water molecules also form hydrogen bonding, significant hydration, therefore, it is very soluble. it is very soluble; while hydrogen and nitrogen are non-polar molecules, so they are very soluble in water.
When the pressure is certain, the solubility of a gas decreases with increasing temperature. There is no exception to this for gases because when the temperature rises, the rate of motion of gas molecules accelerates and they tend to escape from the water surface.
When the temperature is constant, the solubility of a gas increases as the pressure of the gas increases. This is because when the pressure increases, the concentration of the gas on the surface of the liquid increases, so more gas molecules enter the surface of the liquid than escape from the surface, thus making the gas more soluble. Moreover, the solubility of a gas is directly proportional to the pressure (partial pressure) of that gas within a certain range (in the case that the gas does not change chemically with water). For example, at 20℃, the pressure of hydrogen is 1.013×10^5Pa, and the solubility of hydrogen in a liter of water is 0.01819L; also at 20℃, at 2×1.013×10^5Pa, the solubility of hydrogen in a liter of water is 0.01819×2=0.03638L.
There are two ways to express the solubility of a gas. One is at a certain temperature, the pressure of the gas (or the partial pressure of the gas, excluding the pressure of water vapor) is 1.013 × 10^5Pa, dissolved in a body of water, saturated with the volume of the gas (and need to be converted to the volume at 0 ℃), that is, the solubility of the gas in water. Another method of expressing the solubility of a gas is, at a certain temperature, the gas in 100g of water, the total pressure of the gas is 1.013×10^5Pa (the partial pressure of the gas plus the pressure of water vapor at that time) the number of grams dissolved.
The magnitude of the solubility of a gas is determined, first of all, by the nature of the gas, but also with the pressure of the gas and the temperature of the solvent. For example, at 20 ℃, the pressure of the gas is 1.013 × 10 ^ 5 Pa, a liter of water can dissolve the volume of the gas is: ammonia is 702 L, hydrogen is 0.01819 L, oxygen is 0.03102 L. Ammonia is soluble in water, because ammonia is a polar molecule, water is also a polar molecule, and ammonia molecules with water molecules can also form hydrogen bonds, the occurrence of significant hydration, therefore, it is very soluble; while ammonia is a polar molecule, water is also polar molecules, and ammonia molecules with water molecules also form hydrogen bonding, significant hydration, therefore, it is very soluble. it is very soluble; while hydrogen and nitrogen are non-polar molecules, so they are very soluble in water.
When the pressure is certain, the solubility of a gas decreases with increasing temperature. There is no exception to this for gases because when the temperature rises, the rate of motion of gas molecules accelerates and they tend to escape from the water surface.
When the temperature is constant, the solubility of a gas increases as the pressure of the gas increases. This is because when the pressure increases, the concentration of the gas on the surface of the liquid increases, so more gas molecules enter the surface of the liquid than escape from the surface, thus making the gas more soluble. Moreover, the solubility of a gas is directly proportional to the pressure (partial pressure) of that gas within a certain range (in the case that the gas does not change chemically with water). For example, at 20℃, the pressure of hydrogen is 1.013×10^5Pa, and the solubility of hydrogen in a liter of water is 0.01819L; also at 20℃, at 2×1.013×10^5Pa, the solubility of hydrogen in a liter of water is 0.01819×2=0.03638L.
There are two ways to express the solubility of a gas. One is at a certain temperature, the pressure of the gas (or the partial pressure of the gas, excluding the pressure of water vapor) is 1.013 × 10^5Pa, dissolved in a body of water, saturated with the volume of the gas (and need to be converted to the volume at 0 ℃), that is, the solubility of the gas in water. Another method of expressing the solubility of a gas is, at a certain temperature, the gas in 100g of water, the total pressure of the gas is 1.013×10^5Pa (the partial pressure of the gas plus the pressure of the water vapor at that time) the number of grams dissolved.
[edit]Solubility Curve
The significance and application of the solubility curve can be analyzed in terms of points, lines, surfaces and intersections.
1. Point
Each point on the solubility curve represents the solubility of a substance at a certain temperature. That is, any point on the curve corresponds to a corresponding temperature and solubility. Temperature can be found on the horizontal coordinate, and solubility can be found on the vertical coordinate. Solubility curve on the point has three aspects of the role: (1) according to the known temperature to find the solubility of the substance; (2) according to the solubility of the substance to find the corresponding temperature; (3) compare the size of the solubility of different substances at the same temperature or saturated solution in the mass fraction of the size of the solute.
2. Line
The solubility curve represents the solubility of a substance at different temperatures or the change in solubility with temperature. The greater the slope of the curve, the more the solubility is affected by temperature; conversely, it is less affected by temperature. The solubility curve also has three applications: (1) According to the solubility curve, the solubility of a substance can be seen to change with the change in temperature. (2) According to the solubility curve, the magnitude of solubility of substances within a certain temperature range is compared. (3) On the basis of the solubility curve, choose a method for separating certain soluble mixtures.
3. Surface
For any point on the area of the lower part of the curve, the solution prepared in accordance with its data is an unsaturated solution at the corresponding temperature; for points on the area of the upper part of the curve, the solution prepared in accordance with its data is a saturated solution at the corresponding temperature with solute remaining. If you want to make the unsaturated solution (a point in the lower part of the curve) into a saturated solution at the corresponding temperature, there are two methods: the first method is to add solute to the solution to reach the curve; the second method is to evaporate a certain amount of solvent.
4. Intersection
The intersection of two solubility curves indicates that the two substances have the same solubility at the temperatures shown at the point, and the mass fractions of solutes in the saturated solutions of the two substances are also the same.
[edit paragraph]Characteristics of the solubility curve
(1) the solubility curve of most solid substances is low on the left and high on the right, and the solubility increases with the rise of temperature;
(2) the solubility curve of a few solid substances is gentle, and the solubility is little affected by the temperature, such as salt;
(3) the solubility curve of a few solid substances is high on the left and low on the right, and the solubility increases with the rise of temperature;
(3) the solubility curve of a few solid substances is high on the left and low on the right, and the solubility is low on the right, and the solubility is low on the right. (4) The solubility curve of very few solid substances is left-high and right-low, and the solubility decreases with increasing temperature, such as slaked lime;
[edit this paragraph] Application of solubility curve
(l) To check the corresponding solubility of a substance from the known temperature;
(2) To check the temperature of a substance from the solubility of the substance;
(3) To compare the solubility of different substances at the same temperature;
(4) Devise methods of separation or purification of mixtures, e.g., purification of NaCl can be done by evaporation of the solvent, separation of NaCl and NaNO3 can be done by cooling crystallization.
[edit]Calculations on the mass fraction of a solute
Broadly speaking, these include the following four types:
(1) To find the mass fraction of a solute when the amounts of solute and solvent are known;
(2) To prepare a certain amount of a solution with a certain mass fraction of solute, to calculate the amounts of solute and solvent required;
(3) Solution dilution and preparation problems;
(4) applying the mass fraction of solute to the calculation of chemical equations.
[edit]Dilution of solutions
Calculations based on the fact that the total amount of solute remains the same before and after dilution, either by using water, or by using a dilute solution to dilute a concentrated solution.
(1) Dilution of a concentrated solution with water
Set the mass of the concentrated solution before dilution to be m, and the mass fraction of its solute to be a%, and the mass of water added during dilution to be n, and the mass fraction of solute after dilution to be b%.
Then we can get m × a% = (m + n) × b%
(2) Dilute the concentrated solution with the dilute solution
Set the mass of the concentrated solution to be A, and the mass fraction of its solute to be a%, and the mass of the dilute solution to be B, and the mass fraction of its solute to be b%, and the mass fraction of solute after mixing of the two liquids to be c%.
Then we have A × a% + B × b% = (A + B) × c% (1)
or A/B = (c%-b%)/(a%-c%) (2)
[edit paragraph] Calculation of solubility
Mass fraction of the solute = mass of the solute / mass of the solution x 100%
Solubility of a substance = mass of solute / mass of solvent × 100
One of the solubility of a solid
The number of grams of a solid substance dissolved when it saturates in 100 g of solvent at a certain temperature is called the solubility of this substance in this solvent. Symbol: S
Solubility of solids II
The amount of solid solute contained in a certain amount of saturated solution at a certain temperature is called the solubility of the solid substance at the specified temperature. Usually at a certain temperature, the substance in 100g of solvent saturation when the number of grams dissolved to indicate that the solubility of a substance in the solvent, such as 20 ℃, 100g of water can dissolve up to 35.8g of sodium chloride, that is, the temperature of the solubility of sodium chloride for 35.8g/100g of water. The solubility of solid substances and solute, solvent nature, usually the structure of the solute and solvent structure is similar to the easier to dissolve, that is, the so-called principle of similar solubility, which explains part of the fact. Most of the solubility of solid substances with the increase in temperature and increase the temperature of different substances have different effects, according to the relationship between the solubility of substances and the temperature of the solubility curve, the use of solubility curves can be found at any temperature, the solubility of a substance, but also the use of solubility curves to purify and separate certain substances. The solubility of solid substances is less affected by pressure.
Substance color
Red solids: copper, iron oxide Black solids: carbon, copper oxide, iron oxide, iron powder, manganese dioxide
Blue solids: alum, copper hydroxide Red-brown solids: ferric hydroxide Yellow solids: sulphur
Green solids: basic copper carbonate Blue solution: copper sulfate and other soluble copper salts
Yellow Yellow solution: soluble iron salts such as ferric sulfate and ferric chloride
Light green solution: ferrous sulfate and ferrous chloride
Salts insoluble in water and acids: barium sulfate and silver chloride
Substances insoluble in water but soluble in acids: insoluble carbonates such as calcium and barium carbonate; insoluble bases such as magnesium hydroxide and copper hydroxide
Three summaries of the uses of the substances
CO2: insoluble copper salt such as copper sulfate and barium chloride
Three summaries of the uses of the substances
CO2: soluble copper salt such as copper sulfate and barium chloride
CO2: gas: fire extinguishing, soda, greenhouse fertilizer Dry ice: artificial rainfall, chilling agent
Ca(OH)2: building materials, improve acidic soil, Bordeaux liquid, lithosulfuric acid, bleach
CaCO3: building materials
CaO: food desiccant, construction materials
NaCl: flavoring, preservatives, Saline (0.9%) for pickled food
CuSO4: agricultural fungicide, Bordeaux solution, swimming pool disinfection
Na2CO3: detergent, make buns to remove acid and make them fluffy
NaOH: soap, petroleum, papermaking, (solids can be used as a desiccant)
O2: to support the combustion, supply of respiration (aerospace, mountaineering, Diving, saving patients, oxygen-enriched steel)
H2: clean energy, smelting metals
CO: energy, smelting metals, gas poisoning
CH3COOH: flavoring, (the kitchen can be used to distinguish between table salt and soda ash, scale removal, the production of shell-less eggs)
Industrial alcohol: poisonous (containing methanol CH3OH)
Industrial Salt: sodium nitrite NaNO2 is toxic
Four substances commonly known as:
CaO: quicklime NaOH : caustic soda, caustic soda, caustic soda Na2CO3: soda ash (not alkali)
Ca(OH)2: slaked lime, slaked lime Copper sulphate crystals: CuSO4?5H2O Bile alum, blue alum
Dry ice: (not ice) solid Carbon dioxide Sodium carbonate crystals: Na2CO3?10H2O Soda
The main ingredient of marble, limestone is CaCO3
The main ingredient of table salt is NaCl
Hydrochloric acid is an aqueous solution of hydrogen chloride gas
Five on the gas-washing flasks:
1), to test for and absorb a small amount of CO2: the flask is filled with lime-water. gas from a into
Remove and absorb a large amount of CO2: bottle containing sodium hydroxide solution, gas from a into
2), remove HCl: bottle containing sodium hydroxide solution or silver nitrate solution, gas from a into
Testing of HCl: bottle containing silver nitrate solution, gas from a into
3), to remove the water vapor: bottle containing concentrated sulfuric acid, gas from a into
4), gas collection by air displacement method: density greater than air: gas from a into
density smaller than air: gas from b into
collection by drainage method: the bottle is full of water, the gas from b into
5) oxygen delivery: the oxygen bottle is connected to the a (observation of the rate of oxygen delivery, control of the rate of delivery of oxygen)
6) storage cylinders: the bottle is full of gas, to take the gas out, should be from a into the water
Note: gas testing and decontamination and drying: the first test and then decontamination and drying
Six important knowledge tips
1, alkali + salt, salt + salt reaction of the reactant should be dissolved in water, and the product should generally be a precipitate
2, check whether a solution contains SO42-, CO32 -, Cl- order is: take a sample and add excess of dilute nitric acid
(bubbles indicate that there is carbonate, excess purpose is to get rid of carbonate ions), and then add an excess of barium nitrate (such as precipitation indicates that there is sulfate. Excess is to get rid of sulfate ions), and finally add silver nitrate (such as precipitation of chloride ions)
3, gas absorption
NaOH solid: absorb water and acidic gases (such as small amounts of carbon dioxide, sulfur dioxide, hydrogen chloride, hydrogen sulfide)
NaOH solution: acidic gases: CO2, SO2, HCl, etc.
Concentrated sulfuric acid: water and alkaline gases: NH3
4, with concentrated hydrochloric acid and marble reaction to produce carbon dioxide, the resulting gas is passed into the clarified lime water, does not change the turbidity, the reason for this is mixed with hydrogen chloride
5, H2S, HBr, etc., dissolved in water to form anaerobic acid, named hydrosulfuric acid, hydrobromic acid . HIO3 is called iodic acid
6, the smallest molecule of the relative oxides. The one that reacts with both acidic and basic oxides is water
7, The same mass of zinc, magnesium, iron, and aluminum are added to equal mass and concentration of hydrochloric acid (or sulfuric acid),
(1) If the acid reacts completely, as much hydrogen is produced
(2) If the metal reacts completely. Aluminum produces the most hydrogen (Hydrogen mass = Compound value / Relative atomic mass)
(3) The fastest reacting is magnesium and the slowest is iron (from which you can determine metal activity)
(4) If the acid reacts completely, the one that consumes most of the metal is zinc (Metal mass = Relative atomic mass / Compound value)
8, Chemical Fertilizers:
Nitrogen Fertilizers: Makes leaves intensely green (carbamide, ammonium nitrate, urea, etc.) Phosphorus fertilizers: makes roots well developed Potassium fertilizers: makes stems thick and strong (KCl, K2CO3, K2SO4)
Compound fertilizers: contain two or more nutrients (N, P, K) such as KNO3, KH2PO4, NH4H2PO4)
9, By the chemical formula of meta-di-methylhydrazine, C2H8N2, you can get What is the information:
(1) Meta-dihydrazine is an organic substance (2) Meta-dihydrazine consists of the elements carbon, hydrogen, and nitrogen
(3) A molecule of meta-dihydrazine consists of twelve atoms (4) The ratio of the number of atoms of carbon, hydrogen, and nitrogen in meta-dihydrazine is: 1:4:1 (5) The mass ratio of the elements carbon, hydrogen, and oxygen in meta-dihydrazine is: 6:2:7
10, and Meaning of the chemical equation: to 2H2O = 2H2↑ + O2↑ (above the = plus the condition of energization)
(1) Meaning of mass: water under the condition of energization produces hydrogen and oxygen
(2) Meaning of quantity: 36 parts by mass of water under the condition of energization reacts to produce 4 parts by mass of hydrogen and 32 parts by mass of oxygen
(3) Meaning of microscopic: 2 molecules of water produced 2 molecules of hydrogen and 1 molecule of oxygen
11, diamond and graphite have different physical properties because the atoms are arranged in a different order
carbon dioxide and carbon monoxide have different chemical properties because the molecules have different compositions
sodium atoms are different from sodium ions because of the difference in the number of electrons in the outer layer or the number of electrons in the outermost layer
acids are different from bases Because of the different ions contained
The difference between pig iron and steel is because of the different carbon content
The difference between concentrated sulfuric acid and dilute sulfuric acid is because of the different mass fractions
12, to prove that carbon dioxide can react with water experiment: to make purple litmus red, carbon dioxide pass into the water to measure its electrical conductivity
To prove that carbon dioxide can be dissolved in water: open the soda bottle bubble, use a plastic bottle to collect the full carbon dioxide and then collect the carbon dioxide.
To prove that carbon dioxide can dissolve in water: open a soda bottle and bubble it, collect a plastic bottle full of carbon dioxide and then add a certain amount of water, the plastic bottle becomes flat.
13, put metal into hydrochloric acid, at first the reaction is slow (surface rust). Finally also getting slower because the mass fraction of hydrochloric acid becomes smaller
14, prove that potassium chlorate contains the element chlorine: potassium chlorate mixed with manganese dioxide and heated, cooled and then dissolved the reacted substance in water, filtered, to the filtrate add silver nitrate and dilute nitric acid
seven points of knowledge of the chemistry of life
a) on the combustion of substances
1,
Lit two candles of different heights, covered with a beaker, the high candle first extinguished, the reason is that the generated carbon dioxide gas is hotter, rises, and then fills the entire bottle from top to bottom, so when a fire occurs indoors should be wet towel blocking the mouth and nose stooped over to escape from the fire zone, the way to escape from a fire in the forest is: blocking the wet towel to the mouth and nose to escape against the wind
2, in order to ensure safety In order to ensure the safety, in the celebration activities can be filled with helium balloons, not hydrogen.
3,
Gas poisoning is caused by carbon monoxide, to prevent gas poisoning is an effective way to pay attention to ventilation, in order to prevent gas leaks, we often add a special odor in the gas mercaptan (C2H5SH) in order to know the leakage of gas, found that there is a leakage of gas in a timely manner to open the doors and windows, shut off the gas valve, (can not turn on the lights, phone calls, fans, etc.) because these actions will generate sparks. (not turn on the lights, phone, fan, etc. because these behaviors will produce sparks and thus gas explosion), found that some people gas poisoning should pay attention to the patient to move to a ventilated place, artificial respiration, if necessary, sent to the hospital for treatment.
4,
Candle blowing out because of the cold air so that the candle temperature drops to below its ignition point, with the fan the fire is getting stronger because of the provision of sufficient oxygen, increasing the area of coal and oxygen contact.
5,
West-to-east gas is natural gas, the main component is methane, coal mine "gas" explosion of the main gas is also methane, the reason is poor ventilation in the mine, so that methane and air mixed to reach the limit of the explosion by the ignition of the explosion, so in order to prevent the explosion of the coal mine to often maintain ventilation, no fireworks. Strictly prohibit fireworks.
6, light bulbs often have a small amount of red phosphorus, mainly off the oxygen inside the lamp
7,
when a fire occurs to block the mouth and nose with a wet towel is to prevent inhalation of toxic gases. If you encounter a toxic gas (containing chlorine, hydrochloric acid, hydrogen sulfide, ammonia) leakage, we also need to use a wet towel blocked to the mouth and nose, and then fled to higher ground.
2) About food
1,
Putting fresh eggs in lime water can keep them fresh because the carbon dioxide exhaled by the eggs reacts with the lime water to form calcium carbonate, which plugs the pores on the surface of the eggs and prevents them from oxidizing and deteriorating.
2,
In order to prevent food from moisture and deterioration or deformation, often in the food bag filled with gas carbon dioxide or nitrogen; or in the bag to put the desiccant: quicklime, calcium chloride is mainly absorbent, the main iron is to absorb oxygen and water; or to take the vacuum packaging.
3, the gas inside the swim bladder of the fish is mainly carbon dioxide and oxygen
4, when making trowel, add some soda ash mainly to neutralize the acid produced by the fermentation of flour, the carbon dioxide generated can make the bread loose and porous.
5, pesticide residues in vegetables can be soaked in alkaline substances, which can reduce the pesticide properties
6, the astringent flavor of the eggs can be removed by adding a little vinegar
7, the refrigerator can be used to remove the odor of the activated charcoal, the use of activated charcoal adsorptive properties.
8, aluminum pot on the scale (the main component is calcium carbonate and magnesium hydroxide), can be removed by hydrochloric acid or vinegar
Three: environmental issues
1,
Acid rain is due to the oxides of nitrogen and sulfur oxides (such as SO2, NO2) caused by a large number of emissions, the hazards of acid rain: corrosion of buildings, affecting the growth of crops, pollution of rivers, affecting land acidification. Human health, causing land acidification. Measures to reduce acid rain: the development of new energy sources, less use of coal as fuel, coal desulfurization technology.
2,
Automobile exhaust contains CO, NO, SO2, etc., the method of treatment is: change the engine structure, so that the fuel is fully combusted; in the exhaust pipe on the installation of a catalytic converter, so that the CO, NO is converted into non-toxic N2 and carbon dioxide. Control of urban vehicle exhaust air pollution methods are: (1) the development of new energy sources, (2) the use of electric vehicles
3, to prevent water pollution methods: (1) strengthen the monitoring of water quality, (2) industrial waste should be treated and then discharged
(4) the rational use of pesticides and chemical fertilizers (4) prohibit the use of phosphorus-containing laundry detergent (5) to strengthen soil and water conservation, reforestation
Methods of water conservation: secondary use of water (rice-washing water to water flowers), turning off faucets as you go, low irrigation techniques, and secondary use of industrial water.
4, greenhouse effect
The carbon dioxide content in the air is increasing due to the use of coal and petroleum fuels. Adverse effects are: global warming, desertification of land, melting of glaciers at the poles; measures that can be taken are: planting trees, banning indiscriminate logging; reducing the burning of fossil fuels, and making more use of solar energy, wind energy, geo-energy, nuclear energy, hydro-energy, etc. (We can save paper, save energy, plant more trees, and turn off the lights as we please.)