年級

科目

問題的種類

自然科學 大學

為什麼[A(org)]=n[An(org)]成立 (第三張圖equation 7.9) 感謝

Experiment 7 Experiment 7 The partition of Organic acid between Water and Organic solvent Objectives Understand the partition of a solute between two immiscible solvents. Introduction A chemical analysis that is performed primarily with the aid of volumetric glassware (e.g., pipets, burets, volumetric flasks) is called a volumetric analysis. For a volumetric analysis procedure, a known quantity or a carefully measured amount of one substance reacts with a to-be-determined amount of another substance with the reaction occurring in aqueous solution. The volumes of all solutions are carefully measured with volumetric glassware. The known amount of the substance for an analysis is generally measured and available in two ways: 1. As a primary standard: An accurate mass (and thus, moles) of a solid substance is measured on a balance, dissolved in water, and then reacted with the substance being analyzed. 2. As a standard solution: A measured number of moles of substance is present in a measured volume of solution - a solution of known concentration, generally expressed as the molar concentration (or molarity) of the substance. A measured volume of the standard solution then reacts with the substance being analyzed. The reaction of the known substance with the substance to be analyzed, occurring in aqueous solution, is generally conducted by a titration procedure. The titration procedure required a buret to dispense a liquid, called the titrant, into a flask containing the analyte. A reaction is complete when stoichiometric amounts of the reacting substances are combined. In a titration this is the stoichiometric point. In this experiment the stoichiometric point for the acid-base titration is detected using a phenolphthalein indicator. Phenolphthalein is colorless in an acidic solution but pink in a basic solution. The point in the titration at which the phenolphthalein changes color is called the endpoint of the indicator. Indicators are selected so that the stoichiometric point in the titration coincides (at approximately the same pH) with the endpoint of the indicator.

待回答 回答數: 0
自然科學 大學

求解答案是否正確

Multiple-choice questions: (70 points) write the letter of statement that is not true: 1. A.B.U The Drude Model: (a) It is a classical approach using concepts from the kinetic theory of gases. (b) A relaxation-time approximation is used where the probability of collision is l/t. (c) No forces act on the electrons in between collisions. (d) It predicts accurately the electronic heat capacity of metals. 2. The Sommerfeld Model: (a) The crystal potential is replaced by an average Coulomb potential. (b) The separation of states is so close that a continuum model can be applied. (c) The electrons are highly localized due to a strong crystal potential. (Q) The energy of the highest occupied state at 0 K is the Fermi energy. 3. Density of states in k-space, N(k): (a) N(k) is determined by the boundary value conditions. (b) For lattices in any dimensions, N(k) is constant in k-space. (C) N(k) depends on the direction and magnitude of k. (d) It is directly proportional to the volume of the crystal. E影響, c 4. The Fermi surface of a metal: (a) is responsible for many of the transport properties of the metal, (b) depends on the nature of the chemical bonds, (c) is always a sphere, (d) can involve mixing of electron orbitals. ✓ 5. The conductivity of a material () increases with the mobility of its carriers, (b) increases with the density of carriers, (C) it is inversely proportional to the energy gap. cogu changes with temperature. 6. BID Plasmons: (a) They are an important characteristic of the Sommerfeld electron gas model. (b) Plasmons occur spontaneously in metals. (c) They are related to charge density oscillations. (d) The Plasmon energy is typically of the order of 10 eV. The Fermi energy Ef in intrinsic semiconductors 8) is usually close to y E, at OK (b) it ACiD. can increase or decrease with temperature depending on the ratio of hole and electron effective masses, (c) it represents the point at which the probability of occupation is 12, even though there may not been any states with that energy, (d) its value relative to the electronic bands must remain unaffected in the presence of defects or interfaces.

待回答 回答數: 0
自然科學 大學

4.59答案為什麼是a

mass, are 「 PASSAGE PROBLEMS 了 R/S BODY. Dancers experience jjmps they make. Tor example Speed7 sma- jZOnta] ) case7? he box )n foT 7 ere no an en- )1S at- 了1S and 1S Ve Up- glvVen 「graph 1 TV planet, when a dancef ]an head by 過e neck cause 負e head to $ 9g.4% of atypical personsm Janding after a Vertical Jump $ 4.0 m/s to restinatime of 0.20 S. 4,57 What 1$ the magnitude Of the average force that her neck exerts on her head during the ]anding? (3) ON; (b) 6O N; (c) 120 N: must exceed the jow down and come to Tes- The head is about as8. Video analysis ot a 65-kg dancer hows that her head decelerates from hthe force her neck exerts on her head during the ]anding, the force her head exerts On her neck 1S (3) the Sames: (b) greater; (co) smaller: (d) greater during the first half ot the land- uring the second halt of the ]anding. 4.,58 Compared Wit 9 and smaller d 4,59 While the dancer 1S in the air and holding a fixed bose what is the magnitude of the force her neck exertS On her heady (3 ON; (b) 6O N; (o]) 120 N; (0) 180 N. 4.60 The forces ona dancer can be measSsured directly When a dancer performs aJump On a force plate that measSures the 10rfce betWween her feet and the ground. A graph Of force verSus time es a Vertical jump performed on aforce plate is Shown lt es at 1S happening at 0.4 $? The dancer is (3) bendlng 0 1S acceleratling downward; (b) pushtung er legs and is almost ready to leave the ground (o in the air and at the to have just touched the 一 her jump; (d) landing and her feel Figure P4.60

尚未解決 回答數: 1
自然科學 大學

請問一下,第45題怎麼算

96d nt” Chemieal EdUUDT LT 人 說 1 ction below ata certam 1 全 同 同 equilibrium ee 說 ii [Ho2] 三 0.0500 TE 、 ipid container are 總 人 2 抽 Ho(g) + 到(tg) 三一 2HF(g) /@巡 > 1 / 1 語全 全胸 : iibri mmIXtUure, 0 2 於 了 人 0.200 mole of Fz is added to this 1 gquilib- thee 2 caJcuJate the'corcentrations 9f a11 gases 1 )。 入 rium is reesfablished- 2 只汪 人 和 沿之 / (9 1100 K, 及p 0.25 for the following reactlon 1 三入 3 、 一一 所 全生 /4 2SQ23(g) 十 Qz(g) 二二 250O3(9 du Ttbe 選娘 an ial pressures of 502, 人2 te 全 了Cajculate the eduilibrium Partial pressure 人 同 葬 也62人 5O3 produced 自om an initfaL_mixrure In 8 oo 三 Po 王 0.50 atm and Pso, 三 0. 2人 三人 1和 宅及林用 生 ” 46. At 22002C 肥 三 0.050 for the reaction 2509 4 2 yy2(9) +O2(g) =二 2NO() 的 What js 和the partial pressure of NO at equilibrtum as 人選 9 suming he N2 and O2 had initial pressures of 0.80 atm 全 // -彈d 0.20 atm, respectively? @ / 32 5 相/ 和pe )f reactiOn_ we wi study is that having a very 汪 補- 六sma上有value (K<< 1 Solving for equilibrium concen- 一條0說人 frations jm an eduilibrium problem usually requires many mathematica| operations to be performed. How- 說 和 even the math involved in solving edquilibrium problems 。。 %6 2 Ina D6909 , for feactions having smal| K values (K << 1) 1s simpli- 527- fied. Whatassumption js made when solving equilibrium 1 Concentrations for reactions having small 太 values? 534 Le 台 戰 Whenever assumptions are made, they must be checked ler ? (吃 hdiry np general the 59 rule> is used to check t cd 旨 Me Vaudlty of assuming thatx (or 2x, 3x, and so on) is ga 只 sma compared to some number Whenx (or 2x, and so 1 less than 和

待回答 回答數: 0