最新初三化学计算题专题复习（Special+review+of+chemistry+calculation+questions+in+junior+middle+school）优秀名师资料.doc

初三化学计算题专题复习（Special review of chemistry calculation questions in junior middle school）初三化学计算题专题复习(Special review of chemistry calculation questions in junior middle school) The mass fraction of solute in the obtained solution is about () A( 0% B. $number( $number c. $number( $number d. $number( 0% 2, to 100g solute mass fraction 10% of the solution of a substance, respectively, the following operations: ? evaporation of 10g water, no crystal precipitation ? add solute mass fraction of 10% of the same solute solution 10g? add 10g homogeneous solute, and completely dissolved ? add 10g water. The solute mass fraction of the four solutions after operation is from small to large order () A. ?b. ?c. ?d. ? 3, the following solid matter of sufficient quantity and the same quality, solute mass fraction of the same hydrochloric acid mixture, if hydrochloric acid is fully reacted to the ZNCL2 solution, the smallest solute mass fraction is () A( Zn B. ZnO c. Zn (OH) 2 d. ZnCO3 Five, image analysis type choice question Example 4: Existing a mixture of $literal and NaHCO3, a classmate for the determination of its content, take a certain amount of the sample dissolved in water, by dropping into the acid and constantly oscillation, first reaction: $literal + hcl = NaHCO3 + NaCl, then react: nahco3+ hcl = NaCl + co2?+ $literal. It is known that the CO2 density at this temperature is 1.98g/l, experimentally measured CO2 and acid data as shown on the right. (1) When G hydrochloric acid is added, the CO2 is started; = ml in the figure. (2) Please calculate: What is the quality fraction of HCl in hydrochloric acid added to ? What is the quality of $literal and NaHCO3 in the original samples of ? (The percentage is accurate to 0.1% and the quality is accurate to 0.01g) "Same Topic link" 1. The laboratory uses the KCL03 to make the oxygen. The MnO2 in the mixture can be correctly expressed in the image. The mass fraction a% change with time t is () 2, the same quality of Mg, Fe, Zn, respectively, with the amount of acid reaction, the reaction speed and the quality of hydrogen produced the relationship is correct () 3, the amount of Fe and Zn is the same as the quality of the acid complete reaction, the formation of hydrogen mass (m) and time (t) of the relationship is correct () 4, to the sufficient amount of acid to add a proper amount of magnesium powder, the following diagram can correctly indicate that the change is () 5, an extracurricular interest group of students to draw four kinds of experimental operation of the trend of the image, the correct is () A B C D A( Potassium nitrate crystals are continuously added to a certain temperature near saturated potassium nitrate solution b( Adding an overdose of sodium hydroxide solution to the mixed solution of sulfuric acid and copper sulfate C( An overdose of sodium hydroxide solution to the acid D( Dilute sulphuric acid with equal mass and mass fraction of magnesium and aluminium 6, to a mixture of 40g hydrochloric acid and a certain quantity of copper chloride solution into the solution of slowly dropping 20% of sodium hydroxide solution and oscillation, the quality of sodium hydroxide solution and the formation of precipitation as shown in the figure, the following judgments are correct () A. The quality of the final generation of precipitation is 9.8g B. The solute mass fraction of 40g hydrochloric acid is 27.375% C. The quality of the precipitated precipitation increases with the addition of sodium hydroxide solutions D. When adding sodium hydroxide solution to 20g, the reaction solution is sodium chloride solution. Precipitation Quality g 0 g of NaOH solution quality 7, (Jinan city) in a beaker of 100gbacl2 and HCl mixed solution, A $literal solution with a solute mass fraction of 10%, the mass of the mixed solution and the mass of the droplets into the $literal solution as shown in the figure: Please answer questions according to the question: (1) In the experimental process, the gas release, but also can see the obvious experimental phenomenon is 。 (2) The total mass of gas emitted during the experiment is G. (3) When the $literal solution is dropped into the b point of the graph, what is the solute mass fraction in the unsaturated solution obtained by calculation? (The calculation results are accurate to 0.1%) 8, ordinary brass only by copper and zinc, widely used in the manufacture of plates, tubes, etc., also used in casting machinery parts. The existing piece of a. 00g brass sample, a classmate uses an unknown concentration of acid to determine the quality fraction of the CU in the sample. The figures are as follows. Q: (1) The quality fraction of CU in brass. (2) The quality of the H2 produced by the sample fully reacts. (3) Acid solute mass fraction. VI. Experimental data type calculation problem Example 5: A classmate to explore the quality of iron in copper alloy, successively conducted three experiments, the experimental data are as follows: Number of experiments Project First time Second time Third time The quality g of the alloy taken 20 20 40 Quality g of diluted sulfuric acid 100 120 80 The quality g of hydrogen production 0.4 0.4 0.4 According to the student's experiment, try to answer the following questions: (1) In the three experiments, the quality of dilute sulfuric acid solution is _g when the iron in the alloy exactly reacts. (2) What is the mass fraction of iron in the copper-iron alloy? (3) The solution solute mass fraction obtained from the third experiment was _ (the result was retained to 0.1%). "Same Topic link" 1, A, B, c three students respectively take a limestone sample and 50g hydrochloric acid experiment, the results are as follows: Experimental Methyl Ethyl C Quality g of the sample 5 10 15 Quality g of generating CO2 1.76 3.52 4.4 Please: ? the quality fraction of calcium carbonate in the limestone samples. ? the mass fraction of solute in hydrochloric acid. 2, lime plant in order to determine a group of limestone samples of the quality of calcium carbonate, take 4 G limestone samples, the acid 4 times to add the sample (in addition to calcium carbonate in the sample, the rest of the ingredients are neither with hydrochloric acid reaction, nor soluble in water), the full reaction after filtering, drying and other operations, the final weighing, the experimental data are as follows: Dosage of acid Add 5 g for the first time Second time add 5 g Third time add 5 g Fourth time plus 5 g Quality of remaining solids 3 G 2 G L g 1 g (1) The quality fraction of calcium carbonate in the limestone sample is; (2) Calculate the solute mass fraction of the acid (write the calculation process, the result is accurate to 0.1%). 3, (Beijing) Artificial aquaculture seafood needs a large amount of seawater, 1kg water containing sodium ions in the quality of about ten. 76g, the quality of magnesium ions is about 1.29g, also contains a large number of chloride ions and sulfuric acid root ions. According to the calculation, select the two salts from the table below, to prepare one of the simplest and cheapest "artificial seawater", so that the "artificial sea" of sodium elements, magnesium elements in the content and water basically the same. Material $number MgCl2 NaCl MgSO4 Price (Yuan/500g) 7 8 4 12 (1) The two selected salts are. (2) Calculate the cost of the salt required to prepare the 1t "artificial Seawater" (write the formula). VII. Balance of balances 1, each end of the balance is placed in a beaker with a sufficient amount of acid, and the balance is transferred to a beaker, and 5 is put into one of them. 6g Calcium oxide, to another beaker into the appropriate amount of magnesium, in order to maintain balance finally, the need to put the quality of magnesium wafer () A( 5.61g B. 8.00g C. 4.2g d. 6.11g 2, in the balance of two sets of equal quality beaker, the beaker in each Sheng 100g9.8% of the sulfuric acid solution, to two of the simultaneous addition of the metal, the balance is still balanced when the reaction is terminated () A( Zinc, iron each 7g B. Zinc, iron each 5g C. Zinc, iron each 4g d. Zinc, Iron 3g 3, in the balance of the two to find a plate in the top two beaker, respectively, to add the mass of the $literal, to the left of the cup into 0.44gCaO, to make the balance again, to the right beaker to add the appropriate material is () A( 100gcaco3 B. 0.48gMg Powder c. 0.924gmgco3 d. 0.44gcu? Al Alloy 4, in the pallet balance on two plates each put a beaker, two beaker Shengyou, such as quality, and other mass fraction of the sufficient amount of hydrochloric acid, so that both sides maintain balance. Add one to the left beaker. 2gCaO, to keep the sides balanced again, the quality of adding CaC03 to the right beaker is () A( 2g B. 17. 6g c. 20g d. 22. 4g VIII. Comprehensive analytic type selection problem Example 6: The mixed gas of a certain mass of CO and CO2 is obtained by a sufficient amount of BA (OH) 2 solution, which is filtered after full reaction, and the resulting precipitation and the quality of the mixed gas obtained are equal, then the ratio of carbon atoms to oxygen atoms in the mixed gas is () A( 1:1 B. 1:2 c. The D. 181:209 "Same Topic link" 1, in the mixture of CO, CO2 of oxygen elements of the mass fraction of the elements of 64%, the 10g mixed gas first through the full amount of hot copper oxide reaction, the resulting gas into the sufficient amount of lime water, the maximum can be white precipitation () A( Ten G B. 20g c. 30g d. G 2, in the laboratory with iron filings, copper oxide, dilute sulfuric acid for the preparation of copper, the following two ways: (1) Fe H2 cu (2) CuO CuSO4 cu If the same quality of copper is produced by the two methods, the following is said: ? consumes the same quality of copper oxide ? consumes the same quality of iron ? and consumes the same quality of sulfuric acid ? to produce ferrous sulfate in different quality. Which is in line with the actual situation is () A. ?b. ?c. ?d. ? Refer to the answer First, the average type calculation choice question: Example 1: B "The same topic link" 1, a 2, B 3, C, D 4, D II. Sample of the estimated type 2: A "the same topic link" 1, d 2, b 3, a Three, the Special Law type Choice question Example 3: B "The same topic link" 1, c 2, b C IV. Solute mass fraction calculation 1, a 2, B 3, C Five, image analysis type choice question Example 4: (1) 5 444 (2) Solution: The quality of ?444 mLCO2 is: Set to generate 0.88GCO2, the quality of the HCL consumed is x g nahco3+ hcl = NaCl +co2?+ $literal 36.5 44 X 0.88g Solution: x = 0.73g 0.73 = ($number) $number = 7.3% (method has a variety of reasonable points) When ? was added to 5g hydrochloric acid, YG $literal was converted to zgNaHCO3. $literal + hcl = NaHCO3 + NaCl 106 36.5 84 Y 5gx7.3% z Solution: Y $number 06g. Z $number. 84g. The quality of 556MLCO2 is: 556ml? (1000mL)x1.98g/l=1.10g The NaHCO3 mass of the reaction when releasing 556mlco2 is M. The: nahco3+ hcl = NaCl +co2?+ $literal 84 44 m 1. 10g solution: M = 2.10g The quality of NaHCO3 in the original sample was: 2.1g-0.84g= 1.26g A: The quality fraction of HCl in ? hydrochloride was 7.3%, and na2co31.06g., NaHCO3 1.26g in ? original samples. "Same topic link" 1, b 2, a 3, C 4, b 5, B 6, a 7, white precipitation generation; 4.4g 8.1% 8 Solutions: (1) (2) The quality of the H2 produced by the sample exactly reacts to X, and the quality of the HCL consumed is Y. Zn + 2HCl = ZnCl2 + h2? 65 73 2 00g-33.75g =16.25g y x X $number. 5 g y =18.25g (3) The quality of the acid is as follows: $number 25g +0.5g-16.25g=182.5g A: The quality of copper in brass is 67.5%, and the quality of the H2 produced by the sample is 0.5g, the solute mass fraction of acid is 10%. VI. Experimental data type calculation problem Example 5: (1) 80g (2) 56% (3) 33.5% "Same topic link" 1, 80% 14.6% 2, (1) 75% (2) Solution: From the table data that the third time after adding 5 g acid, 3 G calcium carbonate and the acid just completely reaction. The mass of solute in acid is X CaC03 + 2HCl = = CaCl2 + H20 + c02? 100 73 3g x 九年级数学下册知识点归纳= $literal g 垂直于切线; 过切点; 过圆心.The solute mass fraction of acid was: x100%=14.6% （3）圆内接四边形：若四边形的四个顶点都在同一个圆上,这个四边形叫做圆内接四边形.3, NaCl MgSO4 Costs required for NaCl: 1000kgx10.76g/kg? (23/58.5) x (4/500) $ = 218.9 函数的取值范围是全体实数；Cost of MgSO4:1000kgx1.29g/kg? (24/120) x (12/500) yuan = 154.8 yuan 2. 俯角：当从高处观测低处的目标时，视线与水平线所成的锐角称为俯角Balance 1, D 2, a 3, B, c 4, C VIII. Comprehensive analytic type of selection 6: D 一年级有学生 人，通过师生一学期的共同努力，绝大部分部分上课能够专心听讲，积极思考并回答老师提出的问题，下课能够按要求完成作业，具有一定基础的学习习惯，但是也有一部分学生的学习习惯较差，学生上课纪律松懈，精力不集中，思想经常开小差，喜欢随意讲话，作业不能及时完成，经常拖拉作业，以致学习成绩较差，还需要在新学期里多和家长取得联系，共同做好这部分学生行为习惯的培养工作。"Same topic link" 7, a 8, C 3、认真做好培优补差工作。 开展一帮一活动，与后进生家长经常联系，及时反映学校里的学习情况，促使其提高成绩，帮助他们树立学习的信心与决心。"Learn to have it." 其中点在圆上的数量特征是重点，它可用来证明若干个点共圆，方法就是证明这几个点与一个定点、的距离相等。Problem-Solving ideas: The topic of the equation ? write the balance of the chemical formula ? find the relationship between the amount ? list ? solution. (三)实践活动"One (3) the quality of Sheng into H2 is already equal to the average value, according to the principle of" having big and small ", the other two metals are 5.6 g, the quality should be a greater than 0. G, the other is less than 0. 】 43.193.25观察物体2 生活中的数1 P22-23Slightly)