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
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1、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
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
3、 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 solut
4、ion, 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 t
5、he 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
6、, 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
7、 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
8、 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
9、 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
10、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
11、 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
12、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 chlori
13、de 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: Pl
14、ease 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
15、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 samp
16、le, 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
17、 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 dilu
18、ted sulfuric acid 100 120 80 The quality g of hydrogen production 0.4 0.4 0.4 According to the students 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
19、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
20、: 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 o
21、f 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 oper
22、ations, 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
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