作者nauticat (我是野男人)
看板TransBioChem
標題[化學] 問題請教
時間Sun Jun 12 10:20:35 2011
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~
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1F：→ RLCorn:2.氦氣第二游離能 He(g)+→e- + He(g)2+ 已成類氫原子 06/12 14:58
2F：→ RLCorn:4.考慮同離子效應 "雖說幾乎"由強酸提供[H+] 但鹽類水解 06/12 15:01
3F：→ RLCorn:亦須考慮進去 06/12 15:02
4F：→ angel30hyt:3.沒有8S週期表只有到7S 06/12 21:40
5F：→ angel30hyt:1.應該是C 06/12 21:47
6F：→ luky60311:第4的概念完全錯了 06/12 21:47
7F：→ luky60311:弱酸的共軛酸根必須視為"鹼" 06/12 21:48
8F：→ angel30hyt:Rotational spectroscopy or microwave spectroscopy 06/12 21:48
9F：→ angel30hyt:studies the absorption and emission of 06/12 21:48
10F：→ angel30hyt: electromagnetic radiation (typically in the 06/12 21:49
11F：→ luky60311:也就是(1)先進行酸鹼作用 使[HA]反應後變成0.05M 06/12 21:49
12F：→ angel30hyt:microwave region of the electromagnetic spectrum) 06/12 21:49
13F：→ luky60311:[A-]變成0.15M 06/12 21:50
14F：→ luky60311:(2)再帶入Ka就可算出[H+] 06/12 21:50
15F：→ angel30hyt:by molecules associated with a corresponding change 06/12 21:50
16F：→ angel30hyt: in the rotational quantum number of the molecule. 06/12 21:51
17F：→ luky60311:完全根A-水解無關 06/12 21:52
18F：→ nauticat:謝謝了~ 自己唸有時候真的轉不太過來 XD 06/12 22:01
19F：→ c510518:5.ideal gas的u只和溫度變化有關 應該是0吧~ 06/13 19:44
20F：→ nauticat:請問luky大 這兩個不是都是酸嗎?這樣可以酸鹼反應嘛?謝謝 06/13 21:25
21F：推 luky60311:[A-]為鹼 如果有chemical principles 可參考鹽類水解 06/13 21:46
22F：→ luky60311:鹽類之所以會水解(和H2O)反應是因為水中沒有大量H+建立 06/13 21:48
23F：→ luky60311:平衡系 但本題有H+(鹽酸提供)建立平衡系 06/13 21:49
24F：→ luky60311:參考教科書應該就能懂A-為何是為鹼 06/13 21:50
25F：→ nauticat:好~感謝! 06/13 22:37
26F：推 knight791211:你也要考嘉義對吧 一起加油吧 06/27 21:31