[化學] 問題請教

看板TransBioChem作者nauticat (我是野男人)時間13年前 (2011/06/12 10:20)推噓2(2推 0噓 24→)

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幾題化學請教謝謝 1. which of the following electromagnetic radiations corresponds to the dipole transition of pure molecular rotation? a) UV light b) IR radiation c) microwaves d) radio wave 小弟查不到有關分子轉動的偶極躍遷和四種波的關係, 討教一下 2. The ionization energy of H atom is 13.6 eV. What is the second ionization energy of He atom? a) 6.8 eV b) 13.6 eV c) 27.2 eV d) 54.4 eV 小弟寫 b , 因為He有兩個電子,第二顆跟H的一樣,對嘛??? 另外H是不是沒有第二游離能??? 3. Which of the following combination of quantum numbers n and l are forbidden? a) 5d b) 6f c) 8s d) 4f 小弟覺得四個都可以, 是題目有問題嘛? 4. Calculate the pH of a solution made by mixing 50.0 ml of 0.400 M NaA (Ka for HA= 1.0 * 10*-8) with 50.0 ml of 0.100 M HCl . a) 3.65 b) 7.52 c) 8.48 d) 11.6 小弟本來是這樣算: HCl是強酸直接算濃度 ( 0.1M * 50ml ) / (50ml+50ml) 會得到 [ H+] = 0.05 M = 5 * 10*-2 pH = 2-log5 =1.31 (? 沒這選項) 後來查書兩種氫離子的濃度要相加: HCl -----> H+ + Cl- 所以 [H+] = 0.05 M 鹽酸的氫離子 NaA + H2O ----> A- + H3O+ 0.2 0.05 (鹽酸來的) -X +X +X ----------------------------------------- 0.2-X +X 0.05+X 所以 X*(0.05+X) / 0.2-X = Ka = 1.0 * 10*-8 算出來 X = 4 * 10*-8 而 [H3O+] = 0.05 + 4 * 10*-8 (很小吧!) pH = 1.31 跟上一個算法一樣!!?? 請問我哪邊算錯了呢? 5. An ideal gas expands to the vacuum isothermally and irreversibly delta U is a) less than zero b) equal to zero c) greater than zerp d) more information is needed 小弟選 d , 因為看不出來哈哈哈麻煩大家了謝謝~ -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 219.85.142.223

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