Examples.
1 The following are salts ( ).
a．ch3cooh b．caco3 c．ca(oh)2 d．mno2
2 The following substances can be used as nitrogen fertilizers ( ).
a．kcl b．na2so4 c．co(nh2)2 d．ca3(po4)2
3 The fertilizers for sale on the shelves of an agricultural technology station include CO(NH2)2, KCL, and KNO3, and the missing fertilizer varieties are ( ).
A Nitrogen fertilizer B Phosphate fertilizer C Potassium fertilizer D compound fertilizer.
4 The following statement about calcium carbonate is false ( ).
a The main component of marble is calcium carbonate.
b Calcium carbonate is commonly used in laboratories to react with dilute sulfuric acid to produce CO2
c Calcium carbonate can be used as a calcium supplement.
d Lime mortar paints the walls and turns into calcium carbonate after "sweating".
5 Chemical fertilizers are the "food" of crops, and the following statements about chemical fertilizers are correct ( ).
a Urea [CO(NH2)2] is a compound fertilizer.
b Extensive application of chemical fertilizers to improve crop yields.
c Mixing ammonium nitrogen fertilizer with plant ash will reduce fertilizer efficiency.
d Cotton leaves are yellow, potassium fertilizers such as potassium sulfate should be applied.
6 The following statement is incorrect ( ).
a Drinking milk in the elderly can prevent osteoporosis
b Rational use of pesticides and fertilizers to increase food production
c Use comfortable and wear-resistant synthetic materials as fabrics to promote "no worries about wearing" to become a reality
d Lack of trace elements such as phosphorus, potassium, iron, etc., should take a large amount of health products.
7 The following understanding of sodium chloride is correct ( ).
a Composition: Contains sodium and chloride B Properties: Similar to hydrochloric acid, can react with carbonate.
c Uses: Can be used to produce metal sodium d Production: Commonly used sodium and chlorine are obtained through chemical reactions.
8 The substances that are indispensable in the physiological activities of the human body are ( ).
a Formaldehyde b table salt c sodium nitrite d carbon monoxide.
9 In the 11th century, China used the "Zhuo Tube Well" sinking technique to obtain table salt. The main component of table salt is ( ).
a．nahco3 b．na2co3 c．nacl d．naoh
10 The substance commonly known as "soda ash" is ( ).
a．h2so4 b．hcl c．na2co3 d．cu(oh)2
11 The Chinese chemical experts who proposed the combined alkali production method are ( ).
12 In the experiment of "Preliminary Purification of Coarse Salt", the following operation is correct ( ).
13 On May Day, the chemistry interest group came to the school's agricultural base and found that the original green grape leaves turned yellow
a．co(nh2)2 b．ca3(po4)2 c．kcl d．kh2po4
14 The following chemical fertilizers should not be mixed with alkaline substances ( ).
a．nh4cl b．ca3(po4)2 c．k2so4 d．co(nh2)2
15 The following statements about the use of substances are incorrect ( ).
a. Acidic soil with hydrated lime b. Limescale removal with salt water.
c. Refrigerator odor removal with activated charcoal d Sodium bicarbonate**Hyperacidity.
16 The one that can distinguish sodium hydroxide solution from sodium carbonate solution is ( ).
A phenolphthalein test solution b hydrochloric acid c potassium hydroxide solution d potassium carbonate solution.
17 Of the following statements about pesticides and fertilizers, it is incorrect ( ).
a Potassium nitrate (KNO3) is a compound fertilizer.
b Fertilizers and pesticides play an important role in both high and good agricultural yields.
c Hydrated lime powder grinding can identify ammonium chloride (NH4Cl) and potassium chloride.
d After the application of pesticides, there will be no transfer through crops, agricultural products, etc.
18 In order to remove sediment, Ca2, Mg2, SO42 and other impurities in coarse salt, the coarse salt can be dissolved in water, and then the following five steps are carried out: Filtration Add excess sodium hydroxide solution Add an appropriate amount of hydrochloric acid Add excess sodium carbonate solution Add excess barium chloride solution. The correct sequence of operations is ( ).
a．④⑤b．②④c．②⑤d．⑤②
19.From the following substances, fill in the blank with the appropriate substance (fill in the letter before the substance on the horizontal line).
a Sodium bicarbonate b Noble gas c Sodium chloride d Activated carbon.
1) Important condiments in life;
2) one of the main components of fermented flour;
3) It is used to adsorb color and odor in water;
4) It can be used to make electric light sources for various purposes.
20 Combined with the instrument shown in the figure below, complete the relevant problems in the crude salt purification experiment.
1) The name of the instrument is .
2) When filtering coarse brine, in addition to using a glass instrument in the figure, it is also necessary to use (fill in the name).
3) Evaporation of crystallized salt, in addition to the use of the instrument in the figure has to fill in the serial number).
4) The following description of the evaporation crystallization operation is correct
a When the heating is until there is crystal precipitation, the heating is stopped.
b When there are more solids in the evaporation dish, the heating is stopped.
c When the water is completely evaporated, the heating is stopped.
d The evaporation dish should be heated on an asbestos net to prevent breakage.
21 The ocean is a precious natural resource for mankind, and the "salt production" of seawater embodies the wisdom of mankind to use chemical science to conquer and transform nature. By drying seawater, coarse salt can be obtained, coarse salt contains insoluble impurities (such as sediment, etc.) and soluble impurities (such as mgCl2, CaCl2, etc.), and refined salt is made from coarse salt as raw material in industry, and its production process is shown in the figure.
Please answer the following questions:
1) The function of the glass rod in operation b is:
2) The ions removed by adding Na2CO3 solution are filled with ion symbols), and the chemical equation for the reaction of NaOH solution is .
3) The main component of the solute in the filtrate is the chemical formula), and the purpose of adding sufficient dilute hydrochloric acid is to do so
4) If the mass of coarse salt weighed in weighing is 3 g, the quality of refined salt weighed in weighing is 31 g, then the following analysis is correct (fill in the letters).
a The yield of refined salt is 1033%
b There may be moisture in the evaporation operation that has not been evaporated.
c NaCl is generated during the impurity removal process.
d The coarse salt was not completely dissolved during the dissolution operation.
22.After learning the knowledge of acids, alkalis and salts, a chemistry interest group carried out ** activities on the properties of certain salts.
research themes; **FeCl3 solution heated, burning changes.
Related information: Alcohol (C2H5OH) is reducible and can react with Fe3O4 under heating conditions; Fe and Fe3O4 are easily attracted to magnets, and FeO is a black solid and cannot be attracted to magnets; Fe3O4 can react with hydrochloric acid to form salt and water.
1) Experiment 1: About 20ml of saturated FeCl3 solution was heated and evaporated in an evaporation dish, and after boiling, it was found that the solution gradually produced reddish-brown turbidity.
The yellow color of the FeCl3 solution is mainly due to the presence of iron ions in the solution, which are symbolized by iron ions
When heated, FeCl3 is easy to react with water to form reddish-brown substances and hydrochloric acid, and the chemical equation of the reaction:
Inspired by experiments, FeCl3 solution is filled with "can" or "can't") by evaporation crystallization to obtain FeCl3 solids.
2) Experiment 2: The reddish-brown solid obtained by evaporation in Experiment 1 was transferred to the crucible and burned, and the color changed from reddish-brown to reddish-brown.
This process undergoes a decomposition reaction, which, in addition to the reddish-brown substance, also produces water, the chemical equation of the reaction:
Magnesium hydroxide, copper hydroxide and other thermal decomposition can also obtain the corresponding metal oxides, combined with experiments, from the type of substance and its solubility, the corresponding metal oxides can be generated by thermal decomposition.
3) Experiment 3: The group used multiple glass rods dipped in saturated FeCl3 solution and burned them on the flame of the alcohol lamp, and with the continuous heating time, the changes of the surface color of the glass rods were observed in the following order within 1 minute: yellow, reddish-brown, reddish-brown, and black.
Experiment 3 has the advantage of answering 1 point compared to Experiments 1 and 2).
The students had questions about the composition of the black substance. In connection with the flammability, reducibility and other related properties of alcohol, the composition of the black substance was speculated, and it was discussed that it may be one or more of the four substances of Fe3O4.
In order to determine the composition of the black substance, the following experiments were carried out to collect the black substance:
4) Expand and extend.
When preparing FeCl3 solution, in order to prevent the appearance of reddish-brown substances, a small amount of chemical formula can be added to it.
Combined with the knowledge learned, from the perspective of the change of elemental valence, when the reduction reaction of Fe2O3 occurs, the valency of iron before and after the reaction generally changes "up" or "down").
23 After learning about the properties of common salts, a chemistry study group completed the following experiment. The study group examined the composition of the solute in the supernatant of the waste cup. Please complete the following process.
Ask the question] What solutes are in the supernatant?
Make a conjecture] solute is only filled with chemical formula);
The solutes are KCl and BaCl2;
The solute is Kcl and filler chemical formula);
The solutes are KCl and K2CO3;
The solutes are KCl, K2SO4 and K2CO3.
Design Scheme] Communication and Reflection] After discussion, the study group concluded that there was no need to use AGNO3 solution during the experiment, and the reason was
In words).
24.(2019, Shenzhen, Guangdong) Known:
NaHCO3 solids are thermally decomposed.
Na2CO3 does not decompose when heated.
Answer the following questions:
1) The narrative about the NAHCO3 solid is wrong to fill in the label).
A is commonly known as baking soda B is poorly soluble in water.
c can react with dilute hydrochloric acid d is one of the main components of baking powder.
2) To determine the mass fraction of NaHCO3 in a solid sample of NaHCO3 (containing only Na2CO3 impurities and evenly distributed), 50g The sample was heated to the point that the mass no longer changed, and the mass of the remaining solids and the mass of CO2 formation were measured as shown in the figure.
The pH 7 of the NaOH solution (fill in " "=" or " "The CO2 generated by the solution is completely absorbed, and the chemical equation for the reaction is
As can be seen from the data in the figure, the above 5The mass of the 0g NaHCO3 sample that completely decomposes to produce CO2 is g, and the mass of H2O to produce is g.
Calculate the mass fraction of NaHCO3 in this sample (write out the complete calculation steps according to the chemical equation).
Examples. Answer] B Analysis] A, CH3COOH belongs to acids; b. CaCO3 is a salt; c. Ca(OH)2 is a base; D. MNO2 is a metal oxide, so B is correct.
Answer] C Analysis] A. KCL contains potassium and belongs to potassium fertilizer, so it does not meet the topic; b. Na2SO4 does not contain chemical fertilizer nutrients and does not need to be used as chemical fertilizer, so it does not meet the topic; c. CO(NH2)2 contains nitrogen, which is a nitrogen fertilizer, so it is in line with the topic; D. Ca3(PO4)2 contains phosphorus, which is a phosphate fertilizer, so it does not meet the topic.
Answer] B Analysis] CO(NH2)2 belongs to nitrogen fertilizer; KCL belongs to potash fertilizer; KNO3 belongs to compound fertilizer, so it lacks phosphate fertilizer, B is correct.
Answer] Analysis] The main component of marble is calcium carbonate so a is correct; Calcium carbonate is commonly used in laboratories to react with dilute hydrochloric acid to produce CO2,B. Calcium carbonate can be used as a calcium supplement, c correct; The reason for the "sweating" after lime mortar painting the walls is that calcium hydroxide and carbon dioxide react to produce calcium carbonate and water, d correctly.
Answer] C analysis] Urea [CO(NH2)2] belongs to nitrogen, A is wrong; The application of chemical fertilizers in large quantities will cause water pollution and nitrogen pollution, so it should be used reasonably, b wrong; When ammonium nitrogen fertilizer is mixed with plant ash, ammonia gas will be released by the reaction of ammonium salt and alkali, which will reduce the fertilizer efficiency, c is correct; Cotton leaves are yellow, nitrogen fertilizer should be applied, d wrong.
Answer] D Analysis] Milk is rich in calcium, and drinking milk for the elderly can prevent osteoporosis, a correct; Rational use of pesticides and fertilizers to increase grain production, b is correct; The use of comfortable and wear-resistant synthetic materials as fabrics, extend the service life, and promote "not worrying about wearing" to become a reality, C statement is correct; Lack of trace elements such as phosphorus, potassium, iron, etc., if you take a large number of health products, it is harmful to the body, and D is wrong.
Answer] C Analysis] Sodium chloride is composed of sodium and chlorine, a is false; It is not similar to hydrochloric acid, hydrochloric acid is an acid, sodium chloride is a salt, does not react with sodium carbonate, b is wrong; Sodium chloride can be used to produce sodium metal, c correct; Sodium chloride is commonly used in seawater to dry salt, or obtained from salt wells, salt mines, d error.
Answer] B Analysis] Formaldehyde, carbon monoxide, and sodium nitrite are all toxic, so they cannot exist in the human body, and table salt is essential for the human body, B is correct.
Answer] C Analysis] The chemical name of table salt is sodium chloride. a, nahco3 common name baking soda; B, Na2CO3 common name soda ash; c. NACL, commonly known as table salt; D. NaOH is commonly known as caustic soda, caustic soda, and caustic soda, so C is correct.
Answer] C analysis] "soda ash" is not alkali, but salt, sodium carbonate its aqueous solution is alkaline, so it is called "soda ash".
Answer] B Analysis] The Chinese chemical expert who proposed the combined alkali production method is Hou Debang.
Answer] C Analysis] When taking coarse salt, the cork should be placed upside down, A is wrong; A beaker should be applied when dissolving, b error; Filtration of coarse brine is done correctly, c is correct; During evaporation, when there is a large amount of solid precipitation in the evaporation dish, the heating is stopped, and the water is evaporated dry by residual heat.
Answer] A Analysis] The leaf color of the green grape leaves turns yellow, and there is a lack of nitrogen, so nitrogen fertilizer is needed, and CO(NH2)2 belongs to nitrogen fertilizer, A is correct; Ca3(PO4)2 belongs to phosphate fertilizer, B is wrong; KCL belongs to potash fertilizer, C is wrong; KH2PO4 is a compound fertilizer and does not fit the title.
Answer] A Analysis] Ammonium nitrogen fertilizer cannot be mixed with alkaline substances, and a reaction will occur when mixed to generate ammonia and reduce fertilizer efficiency. Ammonium nitrogen fertilizer only has ammonium chloride, which belongs to a correct.
Answer] B Analysis] Modified acidic soil with hydrated lime, using the principle of neutralization reaction, A is correct; Remove limescale with dilute hydrochloric acid instead of salt water, b error; Refrigerator odor is removed with activated carbon, using its adsorption, c correct; Sodium bicarbonate can react with hydrochloric acid, which belongs to the sodium bicarbonate ** hyperacidity, d correct.
Answer] B Analysis] Because the sodium hydroxide solution and the sodium carbonate solution are alkaline, the phenolphthalein test solution added dropwise turns red, and A is wrong; There is no obvious phenomenon in the reaction between hydrochloric acid and sodium hydroxide solution, while bubbles will be produced when hydrochloric acid reacts with sodium carbonate solution, so b is correct; Potassium hydroxide solution does not react with sodium hydroxide solution and sodium carbonate solution, so c is wrong; The potassium carbonate solution does not react with the sodium hydroxide solution and the sodium carbonate solution, so d is wrong.
Answer] D Analysis] Compound fertilizer refers to two or more chemical fertilizers containing two or more nutrients of nitrogen, phosphorus and potassium, so A is correct; Fertilizers and pesticides play an important role in both high yields and good harvests in agriculture, b correct; Hydrated lime powder grinding can identify ammonium chloride (NH4Cl) and potassium chloride two chemical fertilizers, correct; After the pesticide is applied, it will be transferred through crops, agricultural products, etc., and enter the human body.
Answer] C Analysis] In order to remove impurities such as sediment, Ca2, Mg2, and SO42 in coarse salt, an excess sodium hydroxide solution is added to generate a white magnesium hydroxide precipitate to remove Mg2; Add excess barium chloride solution to generate a white precipitate of barium sulfate, and remove SO42; Excess sodium carbonate solution was added to remove Ca2 and excess Ba2+; Then filter, remove all insoluble matter, and add an appropriate amount of hydrochloric acid to remove excess sodium hydroxide.
Answer: (1) C (2) A (3) D (4) B
Analysis] (1) Salt is an important condiment in life, so fill in: c;
2) Sodium bicarbonate is one of the main components of fermented flour, so fill in: a;
3) Activated carbon has adsorption and is often used to adsorb color and odor in water, so fill: d;
4) Noble gases will emit different colors of light when energized, which can be used to make electric light sources for various purposes, so fill in: b.
Answer] (1) Alcohol lamp (2) Funnel (3) 4) B
Analysis] The name of the instrument is the alcohol lamp; When filtering coarse brine, in addition to the use of a glass instrument in the figure is a funnel; To evaporate crystallized salt, in addition to the use of glass rods in the figure, it is also necessary to use the glass rod in the figure for drainage; When heating evaporation, when there are more solids in the evaporation dish, the heating is stopped, and the correct one is b.
Answer] (1) Drainage (2) Ca2 mgCl2 2NaOH===2NaCl mg(OH)2
3) NaCl removes excess sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) (or excess OH and CO32) 4) BC
Analysis] operation B filtration, to use glass rods to drain, the role of all glass rods is drainage; When Na2CO3 solution is added, A2CO3 reacts with CaCl2 to form a calcium carbonate precipitate, all of which removes Ca2; The chemical equation of the reaction with the addition of NaOH solution is MGCL2 2NAOH===2NaCl MG(OH)2; The main component of the solute in the filtrate is sodium chloride; The purpose of adding sufficient dilute hydrochloric acid is to remove excess sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) or to remove excess OH and CO32; If the mass of coarse salt weighed in weighing is 3 g, the mass of refined salt weighed in weighing is 31 g, the possible reason is that there may be water in the evaporation operation that is not evaporated or NaCl is generated during the impurity removal process, b and c are correct.
Answer] (1) Fe3+ FeCl3+3H2O==Fe(OH)3 +3HCl: No
2) 2Fe(OH)3Fe2O3+3H2O insoluble or insoluble base
3) Easy to operate or save energy or experiment time Fe, C, Feo (name is also acceptable) Fe3O4
4) Hydrochloric acid or dilute hydrochloric acid or concentrated hydrochloric acid decreases.
Analysis] (1) The yellow color of FeCl3 solution is mainly due to the presence of iron ions in the solution, and the iron ion symbol is: Fe3+. Therefore, fill in: fe3+
When heated, FeCl3 is easy to react with water to form reddish-brown substances and hydrochloric acid, according to the conditions of metathesis reaction, the precipitate is iron hydroxide, and the chemical equation of the reaction is: FeCl3+3H2O==Fe(OH)3 +3HCl. Therefore, fill in: FeCl3+3H2O==Fe(OH)3 +3HCl
According to the experiment, ferric chloride will be hydrolyzed to form iron hydroxide when heated, so FeCl3 solution cannot obtain FeCl3 solid by evaporation and crystallization. Therefore, fill in: No.
2) Experiment 2: The reddish-brown solid obtained by evaporation in Experiment 1 was transferred to the crucible and burned, and the color changed from reddish-brown to reddish-brown. This process undergoes a decomposition reaction, in addition to the formation of reddish-brown substance, but also the formation of water, that is, the decomposition of iron hydroxide to form iron oxide and water, the chemical equation of the reaction is:
Magnesium hydroxide, copper hydroxide, etc. are insoluble alkalis or insoluble alkalis, and the corresponding metal oxides can also be obtained by thermal decomposition. Therefore, fill in: insoluble alkali or insoluble alkali.
3) Experiment 3 directly takes the sample and burns it on the flame, which is simpler to operate, shorter in time, less in drug dosage, and environmentally friendly than in Experiments 1 and 2; Therefore, it is easy to operate or save energy or experiment time.
The students had questions about the composition of the black substance. In connection with the flammability, reducibility and other related properties of alcohol, the composition of the black substance is conjectured, and the black solid substance after burning must contain iron elements, which may be iron element, ferrous oxide, ferric tetroxide, etc., or it may be that the incomplete combustion of alcohol lamp produces carbon black, so the black solid substance may be one or more of the four substances of FE, C, FEO, and FE3O4. Therefore, fill in: fe, c, feo (name can also be).
According to the experimental phenomenon, the black powder is all attracted by magnets, which may be Fe3O4 and iron, and the solid is dissolved and there are no bubbles after adding hydrochloric acid, indicating that there is Fe3O4 and no iron element, so it can be concluded that the black substance is Fe3O4. Therefore, fill in: fe3O4
4) When preparing FeCl3 solution, in order to prevent the hydrolysis of FeCl3 and the production of reddish-brown substances, a small amount of HCl solution can be added dropwise to inhibit hydrolysis. Therefore, fill in: hydrochloric acid or dilute hydrochloric acid or concentrated hydrochloric acid.
When Fe2O3 is reduced to form iron, the valency of iron before and after the reaction becomes 0 valence from +3, and the valency decreases, so the valency of Fe2O3 generally decreases when the reduction reaction occurs. Therefore, fill in: down.
Answer] KCL K2SO4 K2SO4 (or K2CO3 and other reasonable can be) There is a white precipitate.
The clarified waste must contain KCL, and the presence of KCL is not required.
Analysis] According to the discussion of the excess of reactants and the possible conditions of the products, the solute is Kcl; The solutes are KCl and K2SO4; According to the title, the conjecture is correct, only need to prove that the solution contains BaCl2, at this time, as long as it is proved that the solution contains Ba2+, at this time, it is necessary to generate a white precipitate, just add K2SO4 or K2CO3; There is no need to use AgNO3 solution during the experiment, the reason is that the clear waste liquid must contain KCL, and there is no need to prove the presence of KCL.
Answer] (1) B
2）①＞co2 + 2naoh = na2co3 + h2o
Solution: Let the mass of NaHCO3 in this sample be x.
x = 4.2g
The mass fraction of NaHCO3 in this sample is 42g/5.0g 100% 84%
A: The mass fraction of NaHCO3 in this sample is 84%.
Analysis] NaHCO3 belongs to salt and has the properties of salt and belongs to the statement about NaHCO3 solids is wrong is B, sodium hydroxide belongs to alkali and belongs to pH 7;The chemical equation for the reaction of CO2 with sodium hydroxide solution is CO2 + 2NaOH = Na2CO3 + H2O; According to the image, the mass of carbon dioxide produced is 11g, the mass of the generated water is 50g-3.45g-1.1g=0.45g.