自然科學 大學 1年以上以前 想問3-9的a跟c Problems 3-1. Explain the difference between *(a) random and systematic error. (b) constant and proportional error. *(c) absolute and relative error. (d) mean and median. *3-2. Suggest two sources of systematic error and two sources of random error in measuring the length of a 3-m table with a 1-m metal rule. 3-3. Name three types of systematic errors. *3-4. Describe at least three systematic errors that might occur while weighing a solid on an analytical balance. *3-5. Describe at least three ways in which a systematic error might occur while using a pipet to transfer a known volume of liquid. 3-6. Describe how systematic method errors may be detected. *3-7. What kind of systematic errors are detected by varying the sample size? 3-8. A method of analysis yields masses of gold that are low by 0.4 mg. Calculate the percent relative error caused by this result if the mass of gold in the sample is (a) 500 mg. (b) 250 mg. V(c) 125 mg. (d) 60 mg. 3-9. The method described in Problem 3-8 is to be used for the analysis of ores that assay about 1.2% gold. What minimum sample mass should be taken if the relative érror resulting from a 0.4-mg loss is not to exceed *(a) -0.1%? (b) -0.4%? (c) -0.8%? (d) - 1.1%? 3-10. The color change of a chemical indicator requires an overtitration of 0.03 mL. Calculate the error if the total volume of titrant is percent relative (a) 50.00 mL. (c) 25.0 mL. 3-11. A loss of 0.4 mg of Zn occurs in the course of an percent relative analysis for that element. Calculate the error due to this loss if the mass of Zn in the sample is *(b) 10.0 mL. (d) 30.0 mL. 190 (c) 188 (d) 4.52 x 103 4.63 x 103 4.53 x 10 ³ √6 *(a) 30 mg. (b) 100 mg. *(c) 300 mg. (d) 500 mg. 3-12. Find the mean and median of each of the following sets of data. Determine the deviation from the mean for each data point within the sets, and find the mean devi- Vation for each set. Use a spreadsheet if it is convenient. *(a) 0.0110 0.0105 (b) 24.53 0.0104 24.68 24.81 24.77 39.61 862 (f) 850 MA 3-13. Challenge Problem: Richards and W the molar mass of lithium and colle data. 24.73 Experiment 1 2 3 4 5 6 194 447 X 10 7 448 X 107 4.58 X 10 (a) Find the mean molar t workers. (b) Find the median molar ma (c) Assuming that the cam molar mass of lithium is the absolute ertor and of the mean value demi Willard. (d) Find in the chemical ues for the molar mus since 1910, and ag a table or spreadshera 1817 given in the a Richards and Willd. Com mass versus year to la of lithium has chang Suggest possible abruptly about 18 ant de (e) The incredibly deals Richards and W that major changes will occur. Disc calculation in pat (f) What factors ha since 1910? (g) How would you mass? 6See Chapter 2 of Applications of Microsoft Excel in Analytical Chemistry, 4th ed., for information about statistical 7T. W. Richards and H. H. Willard, J. Am. Chem. Soc., 1910, 32, 4, DOI: 10.1021/ja01919a002. built-in statistical functions. "Answers are provided at the end of the book for questions and problems marked with an asterisk The I of ₂ or inc rce of able vas error c often in individu ate resul data in rtainties. dimensio andom e analysts The result 待回答 回答數: 0
自然科學 大學 約2年以前 想問這兩題解法與解析 感謝🙏 方法 習題 4.4 習題 4.5 4.5 | X, 加成至烯類:鹵化作用。1 下列烯類經酸催化進行水加成後,你預期將會得到什麼產物? CH3 (a) CH3CH₂C=CHCH₂CH3 (b) - 甲基環戊烯(1-Methylcyclopentene) (c) 2,5- 二甲基 -2- 庚烯(2,5-Dimethylhept-2-ene) 你建議用什麼烯類來製造下列醇類? OH (a) CH3CH2CHCH3 OH (c) CH3 CH 3 OH 1 (b) CH3CH₂-C-CH₂CH3 CH3 待回答 回答數: 0
自然科學 大學 約2年以前 請問第26題⋯ 我的計算機無法計算三次方根 但由答案回推又不正確 想請問我的式子是否有誤? 3 48= 3a a Jr (2)4.42g/cm (C) Sodium crystallizes in a body-centered cubic structure (as drawn here) with a density of 0.97g/cm². Estimate its atomic radius. (A) 95pm (B)320pm (C)370pm (D) 190pm. p=0191= (brige)x a a 1.903x10 a² = 2.903x10? (108台大A) "in a face centered cubic lattice. The density of (D) - ha 3 Go 6x102 Q3 cm 27. Tunntal mare only miato 11izen in 已解決 回答數: 2
自然科學 大學 約2年以前 大學普化 方智化學第六題 ow Na k 7 CI o se Br Chapter 2 化學鍵結 AH -C=CH 升二技插大 3. Brigma The bond between the carbon atoms in acetylene (HCCH) consists of ) (A)6 pi electrons (B)4 pi and 2 sigma electrons (C)6 sigma electrons (D)2 pi and 4 sigma electrons (E)3 pi and 3 sigma B) B 7.(BCDE) electrons. 【84 成大化學) 14.(B) 20.(C) 4. E ) (A)NO; [83 中興A] Which of the following has a triple bond? (B)O2 (C)C12 (D)CO; (E)CN-. Which one of the following element pairs has the lowest electronegativity (B) 27.(D) 34. (C) C) 41.(CD) 1 G difference and thereby is the least polan? Få 10 323.49 B) (84 5% *ILI) -) 48. (A) 6. NET 2 > 2 D) 58. (D) 62. (B) 69. NO+ D Obind (219) O 发 (A)SeF (B)Seci (QKBr (D/NaCl (E)KAT. 11 The compound Sio does not exist as a discrete molecule while CO2 does. This can be explained because ly 2 ep 3 15 aly zp (A)the Si–O bond is unstable (B)The Lewis structure of SiO has an even number of electrons (C)The SiO2 is a solid while CO, is a gas (D)the 3p orbital of the Si has little overlap with the 2p of the 0 (E)none of the these. V MOJT 515 1 - 4 40 (成大】 Yi (4 0 atom) (86 58*A] 7. In order to explain the valence observed for many of the elements 0 -Si-O in terms of electron configurations, it is often useful to look at electronis staies slightly different from the ground state in comparing 0-41-0 the ground state of boron with the state more useful to describe 0 bonding, the number of unpaired electrons goes from (A)1 to 2 (B)1 to 3 (C)3 to 4 (D)3 to 5 (E)none of the above. (集 (80 清大B) Which of the following compounds should not exist? ( (, 【85 成大A】 alf 566-32 Cle 32-8-24 2-89 cild 14 1 he atoms 83 中興A) mm bove. B 29 p. 1 1 be a ) \CHE > ? (A)Na,P (B)(NH4),PO, CIPO. DPH xH)POCI,, Maspal sput 中興A] Pa zorgt O 15412 = 1) O-P- 5 5+12= 1) 10-4 - 13 13-12=1 -- cl-P-0 待回答 回答數: 0
自然科學 大學 2年以上以前 普通物理 想請問這題該如何計算呢? What vertical launch speed is necessary to get a rocket to an alti-tude of 1200 km? 答案為4.45km/s 待回答 回答數: 0
自然科學 大學 2年以上以前 求解 為什麼動量不需要代速度值?🤔 6.51 Using Heisenberg's uncertainty principle, calculate the uncer- tainty in the position of (a) a 1.50-mg mosquito moving at a speed of 1.40 m/s if the speed is known to within £0.01 m/s; (b) a proton moving at a speed of (5.00 + 0.01) X 104 m/s. (The mass of a proton is given in the table of fundamental constants in the inside cover of the text.) (a) Ax >= h bar /24p = 6.626*10-34/(1.5*10-6*0.01)/41 = 4/41*10-27 m (b) Ax >= h bar/24p = 6.626*10-34/(1.67*10-27*0.01)/41 = 3/41*10-10 m * 尚未解決 回答數: 1
自然科學 大學 2年以上以前 水文學——降水與損失 如圖,請問有人知道這兩題該怎麼算嗎? 翻遍教科書教過的內容根本沒想法⋯ > 0 2-14 有一矩形集水區,其四個角落的座標分別為(0,0),(0,10), (14,10) 和 (14,0)。集水區內設有四個雨雨量測站,各測站所在位置的座標及降雨量如下 表。所有座標值的單位均為公里。試以徐昇氏法推算此集水區的平均降雨量 及逕流總體積(註:假設無任何降雨損失) o 雨量站位更 (4,2) (4,7) (11 , 7) | (11,2) 降雨量(cm) 1.5 2.0 2.4 4.3 ( 86 水利工程簡任升等) 待回答 回答數: 0
自然科學 大學 2年以上以前 求證明(b)的過程😭感謝~ (I) A soccer player kicks a ball at 15 m/s at 20° above the horizontal to another member of the team. At what speed should the second player run in order to reach the ball just as it lands? The initial separation of the players is 25 m. he (II) A basketball player throws the ball with initial velocity vo at above the horizontal to the hoop which is located a horizontal distance L and at a height h above the point of release, as shown in Fig. 4.44. (a) Show that the initial the speed required is given by an vſ gL 2 cosO(tan 9 - h/L) (b) Show that the angle a to the horizontal at which it reaches the hoop is given by tan a = 2h/L - tan 0. = Vo h L FIGURE 4.44 Problem 16 待回答 回答數: 0
自然科學 大學 2年以上以前 求過程感謝😭 5. (1) A projectile lands at the level from which it was fired. (a) For what initial angle is the horizontal range equal to the maximum height? (b) For what initial angle is the range equal to half the maximum height? 6. (II) A projectile is fired up an incline with an initial speed vo at an angle o to the horizontal, as shown in Fig. 4.42. (a) If the angle of the incline is a to the horizontal, show that the range along the incline is 2võ sin(0 – a) cos e 0 R = g cosa a (b) Recast this expression for R by using a trigonometric identity for sin A cos B. For what value of 8 is R a maxi- mum? (c) Show that the maximum value of R is vô R= g(1 + sin a) 90-0-2x 0-a 001 R 待回答 回答數: 0