Re: [化學] 台大普化B 96~100 共7題

看板TransBioChem作者Vencol (Vencol)時間12年前 (2012/07/06 16:23)推噓0(0推 0噓 11→)

留言11則, 4人參與討論串2/2 (看更多)

※ 引述《Highhuman (Ryan)》之銘言： : 以下這幾題，是我目前仍然不太會算的題目: : 1.A gas sample containing of CO2 and N2 in 1:2 molar ratio has a volume of : 。 : 350ml at 40 C with a CO2 partial pressure of 560 torr. What is the : volume of the mixed gases under STP condition ? : 。 CO2 分壓 : 560torr = P(總壓) x X1 (CO2莫耳分率) 所以 P (總壓) = 560 torr / (1/3) = 1680 torr 利用 PV = nRT 反推回求 n (1680 / 760) ( 0.35 ) = (n) (0.082) (313) atm L mole K n = 0.03 又 STP 下每mole體積的氣體 =22.4 L 所以體積 ==> 0.03 x 22.4 = 0.672 (L) : 2.The decomposition of dimethyl ether , (CH3)2O , at510 C is a first-order : process wuth a rate constant of 6.8*10^-4 s^-1. : (CH3)2O (g) -->CH4 (g) + H2 (g) + CO(g) : If the initial pressure of (CH3)2O is 135 torr , how long will it take : when the pressure of (CH3)2O drops to 51 torr ? : (A)17.9 s (B)1020 s (C)1430 s (D)1.23*10^5 s 原本的一級反應式是這樣寫 ln [A] = ln [A]0 - kt 但今天妳牽扯到P的變化所以來找初P跟濃度的關係對於理想氣體而言必須遵守 PV = nRT 所以移項得 P = nRT/V = (n/V) RT n/V = C 即為濃度所以把原本的一級反應式改寫成 ln (P0 / Pi) = ln (C0 / Ci) = kt ln (135/51) = (0.00068) (t) ===> t = 1431.5 : 3.Consider the equilibrium :N2O4 (g) <---> 2NO2 (g) : del H = 58.0 KJ , which of the following will shift the equilibrium to the : right ? : (A) A catalyst is added to the system. : (B) N2 is added at constant volume. (我是這個選項不會 XDD") : (C) The volume is decreased. : (D) The temperature is increased. 這種題目主要是勒沙特略原理記住一個關鍵就好如果系統中被加入一個不會參予反應的氣體 ex: N2 或是鈍氣那麼 A 系統總壓不變 , 則有效總壓減少 , 反應朝係數大方向反應直到達平衡 B 系統體積不變 , 則有效總壓不變 . 反應也不會改變 : 。。 : 4.At 25 C , E cell = 1.47 V for the voltaic cell: : 2+ 2+ : V (s) | V (1M) || Cu (1M) | Cu (s) : (A)V (s) is the anode. : (B)V (s) is the negative electrode. (正負極我常搞混，怎麼簡單扼要判斷呢?!) 陽極氧化陰極還原電池跟電解不要搞混就好 : (C)Electrons flow from V (s) to Cu (s). : (D)The cell potential (E cell) of the reaction is zero at equilibrium. : 5.Which of the following involve(s) in an increase in the entropy of the : system ? : (A)grinding a large crystal of KCl to powder (這選項的意思，不是很懂@@") 把晶體導成粉末所以雖然質量不變但是總體積大大提升了 : (B)Br (g) -> Br2 (l) : (C)O2(298K) -> O2(373K) : (D)NH3 (1atm , 298K) -> NH3 (3atm , 298K) (這個講一下好了^^) 溫度不變的情況下體積反比於壓力所以體積變小了 : (E)mixing benzene with toluene (Both have similar intermolecular forces) : ( (E)選項還是無法理解!!) 兩者性質類似可以互溶而不管什麼物質在戶溶之後均會讓亂度增加這可以證明只是..為了考試先記結論吧 : 6.Which of the following statements is(are) true ? : + : (A) O2 would give a bond order of 2.5 : (B) C2 is diamagnetic : (C) Six electrons are involved in pi ponding in benzene , C6H6 : + - : (D) N-O bond length NO < NO2 : 2- : (E) The carbon-carbon bond in C2 is stronger than the one in CH3CH3 這題是每個選項嗎.... : 7.Which of the following statements related to alkali metals and : alkaline earth metals are incorrect? : (A)Thay can all be obtained via electrolysis of their molten salts.: X 我覺得不算全對氮不之道是不是吹毛求疵例如說 Fr 有放射性就不能用這方法 (B)Their oxides can all be dissolved in the strong acid. O 兩者氧化物皆為鹼性可溶於強酸中無誤 : (C)Their carbonate salts are all fairly soluble in water. X 鹼土族有部分是難溶 : (D)Their ions present in water are all colorless and not reactive. X ^^^^^^^^^^^^^ ^^^^^^^^^^^^ 都錯 (E)Alkaline earth metals can form compounds of oxidation numbers : 2 : +1 and +2 , because of the presence of ns electrons in their : outer shells. O : (上面這題我一直不知道正解到底是什麼?!XDD") -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 123.240.187.126

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Carlchen

07/06 16:29, , 1^F

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Vencol

07/06 16:33, , 2^F

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Highhuman

07/06 16:35, , 3^F

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