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1、电子商务网站（chinese ecohillerce website)determination of molecular structure of ethanolfirst, explore the impulsein the middle school chemistry t eaching material seco nd, six th, third has such an experiment: "experimental device" as shown. a small amount of sodium in a flask; a slow drop of a

2、nhydrous ethanol from a funnel into a certain amount of substance the amount of ethanol and the complete reaction of sodium h2 released from the bottle into the middle of the hydraulic cylinder, by measuring the volume of the water in the cylinder, we can see that the reaction volume of h2. accordin

3、g to the data, the structure of ethanol is deduced."the purpose of this experiment is to obtain accurate volume data of h2 to determine the molecular structure of ethanol, so the measurement of gas volume with drainage method has become the key of the experiment how can i accurately measure the

4、 volume of h2 to ensure the success of the whole experiment? under the teacher's suggestion, the students asked themselves to operatetwo, the spark of thinkingaccording to the device given in the book, students encountered many problems throughout the experiment, such as: how to accurately measu

5、re the volume of ethanol? in the process of reaction, the sodium alcohol precipitated by the reaction between ethanol and sodium, which is attached to the surface of sodium, interferes with the contact between ethanol and sodium, thus preventing the reaction, and how to solve this problem? in the ca

6、se of no tightness in the device, the volume of the h2 is much smaller than the theory that the volume of the h2 should be generated, and why? what improvements should be made for the experimental equipment?three 、 experimental designaccording to the above doubts, students access to the data, design

7、ed different experiments to solve the problemquestion 1: how can i accurately measure the volume of ethanol and add it to a flask?1, the required volume of ethanol is less than 10ml, to accurately measure the ethanol volume available burets and can replace the burette separatory funnel in the origin

8、al device, can achieve the measurement with the volume of alcohol, can control the flow of liquid2, because the ethanol density, gas bubbles in the burette tip is not easy to drain, so the method should not be used for acid solution in anhydrous ethanol was injected into the burette this should be t

9、he buret tip into ethanol, cork, with ear wash ball ethanol and then close the cock into the burettequestion two: during the experiment, open the burette piston, why can't the ethanol f1ow out smoothly? how to solve?when the piston is opened, the bottle of alcohol is burette produced in the h2 a

10、nd air pressure boosting and drop down, even if the drop, when the amount of ethanol is low, air pressure and h2 is greater than the atmospheric pressure, the escape losses add to the burette, accurate determination of the actual release of h2 volume to make the correct calculation.solution: put the

11、 plug in the flask 3 holes, inserted below the piston burette respectively, rectangular glass a short glass tube and a derived h2 tube with a rubber plug, the burette and short glass tube connected, when the piston is opened, the pressure and the glass burette tip mouth pipe pressure can keep the ba

12、lance in the buret to alcohol can flow down until all dropquestion three: how to increase the con tact area between na and ethanol so as to make ethanol react adequately.the sliced sodium metal is quickly packed into a flask with a proper amount of kerosene, heated, fused, and strongly oscillating,

13、and the sodium is broken into tiny sodium particles - sodium mud, which is used after dumping of kerosene.question four: how to reduce the experimental error so that the volume of the h2 is close to the true value?1, the catheter in the glass tube filled with water, so that the ends are not into the

14、 water, otherwise the measured volume of h2 should be equal to the volume of water in the check into the cylinder and the volume of water in the conduit2 drops of alcohol, the speed is not too fast, in order to avoid the thermal reaction of alcohol gasification, not glass tube with reflux, h2 into t

15、he jar, not all the alcohol reacts with sodium, resulting in the release of 112 is smaller than the theoretical valuequestion five: where does the device use the drainage method to measure the volume of gas? how can it be improved?in reading a shows the number before adjusting cylinder position, the

16、 liquid level and the jar level is flat, with the gas pressure is equal to atmospheric pressure, the experimental result is correctthe improved device, as shown in fig：after the reaction stopped,the air guiding port to the cylinder into the water, cooling gas to be collected after adjusting the posi

17、tion of the cylinder, cylinder and liquid leve 1. read a level shows the number is h2 volumefive, experimental inquirythe volume of the h2 is measured according to the teaching apparatus and the improved device, and the following table is filled:ethanol dosage (mol), na (g), h2 volume (ml), original

18、 unit, improved device six, and experimental conclusionsseven, experimental development1. in order to measure the structure of ethanol, an experimental device for measuring the hydrogen volume with anhydrous alcohol and sodium was designed and the experiment was carried out the experimental instrume

19、nts available are shown in the figure,please answer the following questions:(1) the correct device for measuring the volume of hydrogen isb. (f订1 in the serial number)(2) the role of the connecting funnel between the a part of the unit and the distilling flask is c. (fill in the serial number)a, pre

20、vent anhydrous alcohol volatilization b. , ensure that the experimental device is not leakc. makes anhydrous alcohol easy to drip(3) before the experiment will advance small sodium in xylene melting into a plurality of small beads of sodium cooled, poured into the flask, its purpose is to prevent th

21、e sodium reaction with air, in creasing the contact area of ethanol and sodium, fully reacting(4) the density of anhydrous alcohol was known to be 0. 789 g, cm - 1, and 2. oml ethanol was removed after complete reaction (sodium excess), 390 ml (as standard condition) gas was collected the number of

22、hydrogen atoms in a molecule of ethanol that can be replaced by sodium is 1, thus determining the structural formula of ethanol instead of hydrogen.(5) the results measured by the experiment were on the high side, and the possible cause was ab. ("11 in the serial number)a. this experiment is ca

23、rried out at room temperature, b. anhydrous alcohol mixed with trace methanolc, the reaction between absolute alcohol and sodium is not complete enough2. the chemical formula of ethanol is c2h60. because of the common isomerism of organic compounds, it is presumed that the structure of ethanol may b

24、e one of the following two.for the determination of the structure should be qualitative, using material specific quantitative experiments are ethanol, sodium, water and the necessary instruments, please a, b, c and d four students directly using the figure given device began to experiment to determi

25、ne the structure of ethanol.(1) student a is given a set of experimental data:ethanol molar volume of hydrogen (mol) 0. 10 (l) 1. 12 (standard) according to the above data structure inference should be 1 (with ethanol (i), (ii) said, the reason for that ethanol molecules) have a different h with the

26、 other five h, so as to determine the structure of ethyl alcohol molecular i(2) class b were accurately weighed 4.60 g ethanol several experiments the results showed that the volume of water displaced within the cylinder as the h2 volume is converted into a standard condition after the generation of

27、 less than 1. 12 l, if the error itself and ignore a b caused by reading, then b is thought to be the result of samples containing a small amount of water caused by the do you think, right? not correct (fill in ''correct7' or ，incorrect/，) if you think that is correct, please explain the

28、 reason; if you think that is not correct, the reason for this situation is what? between the jar and a water glass conduit volume without counting.(3) classmates think the key of successful experiments are as follows: the good air tightness device to start before the experiment to accurately determ

29、ine the calculation method of the amount of ethanol and sodium enough the jar must be filled with water and hydrogen volume correct and accurate data among them, the correct ones are. (fill in the serial number)(4) classmate ding does not want to determine the amount of ethanol by weighing the quali

30、ty of the alcoho 1. then he needs to know the density of the given ethanol sample(5) after the experiment, four students with the analysis of the relationship between the ethanol and the amount of sodium from the possible structure of ethanol is discussed, when the ethanol amount of substance is n m

31、ol, then the value of the amount of substance of sodium requirements must be greater than n mol.five, infonnation link1, high school chemistry (test revision, compulsory plus optional) second volumes, 164 pages.2, "middle school chemistry teaching dem on strati on and quest/, p166-167.3, chemis

32、try teaching, 2003, p5-6 "on the determination of ethanol structural formula" experiment improvement4, chemistry teaching, 2004.5, pll "on the determination of ethanol structure type experiment" re improvement5, chemistry teaching, 2004. 11, p7, ，zinquiry activity on the experime

33、ntal error of gas measuring devicedetermination of molecular structure of ethanola, suspicionsin the middle school chemistry teaching material second, sixth, third has such an experiment: "'experimental device" as shown. a small amount of sodium in a flask; a slow drop of anhydrous eth

34、anol from a funnel into a certain amount of substance the amount of ethanol and the complete reaction of sodium h2 released from the bottle into the middle of the hydraulic cylinder, by measuring the volume of the water in the cylinder, we can see that the reaction volume of h2. according to the dat

35、a, the structure of ethanol is deducedthe purpose of this experiment is to obtain accurate volume data of h2 to determine the molecular structure of ethanol, so the measurement of gas volume with drainage method has become the key of the experiment how can i accurately measure the volume of h2 to en

36、sure the success of the whole experiment? under the teacher，s suggestion, the students asked themselves to operatetwo, the spark of thinkingaccording to the device given in the book, students encountered many problems throughout the experiment, such as: how to accurately measure the volume of ethano

37、l? in the process of reaction, the sodium alcohol precipitated by the reaction between ethanol and sodium, which is attached to the surface of sodium, interferes with the contact between ethanol and sodium, thus preventing the reaction, and how to solve this problem? in the case of no tightness in t

38、he device, the volume of the h2 is much smaller than the theory that the volume of the h2 should be generated, and why? what improvements should be made for the experimental equipment?three 、 experimental designaccording to the above doubts, students access to the data, designed different experiment

39、s to solve the problemquestion 1: how can i accurately measure the volume of ethanol and add it to a flask?question two: during the experiment, open the burette piston, why can，t the ethanol flow out smoothly? how to solve?question three: how to increase the con tact area between na and ethanol so a

40、s to make ethanol react adequately.question four: why is the volume of 112 produced in experiments smaller than the theoretical value? how to improve?question five: where does the device use the drainage method to measure the volume of gas? how can it be improved?four, experimental inquiry1 、 experi

41、mental improvement device2, data analysisethanol dosage (mol), na (g), h2 volume (ml), original unit, improved device five, and experimental conclusions:six, the experimental sentimentseven, experimental development1. in order to measure the structure of ethanol, an experimental device was designed

42、for the reaction of anhydrous alcohol with sodiumplease answer the following questions:(1) the correct device for measuring the volume of hydrogen is. (fill in the serial number)(2) the function of the connecting funnel between the a part of the unit and the distilling flask is. ("11 in the ser

43、ial number)a, prevent anhydrous alcohol volatilization b. , ensure that the experimental device is not leakc. makes anhydrous alcohol easy to drip(3) prior to the experiment, a small piece of sodium was dissolved into small amounts of sodium beads in xylene after cooling, it was poured into a flask.

44、(4) the density of anhydrous alcohol was known to be 0. 789 g, cm - 1, and 2. oml ethanol was removed after complete reaction (sodium excess), 390 ml (as standard condition) gas was collected the number of hydrogen atoms in a molecule of ethanol that can be replaced by sodium is determined by the st

45、ructural formula of ethanol instead of hydrogen(5) the results measured by the experiment are on the high side (fill in the serial number)a. this experiment is carried out at room temperature, b. anhydrous alcohol mixed with trace methanolc, the reaction between absolute alcohol and sodium is not co

46、mplete enough2. the chemical formula of ethanol is c2h60,because of the common isomerism of organic compounds, it is speculated that the structure of ethanol may be one of the following two.for the determination of the structure should be qualitative, using material specific quantitative experiments

47、 are ethanol, sodium, water and the necessary instruments, please a, b, c and d four students directly using the figure given device began to experiment to determine the structure of ethanol.(1) student a is given a set of experimental data:the amount of ethanol (mol), the volume of hydrogen (l) 0. 10, 1.12 (standard condition), according to the above data, the st