作者finalpoet (finalpoet)
看板TransBioChem
标题[问题] 普化的小小题目
时间Wed May 19 22:46:27 2010
1) Two solutions, initially at 24.60°C, are mixed in a coffee cup calorimeter
(Ccal = 15.5 J/°C). When a 100.0 mL volume of 0.100 M AgNO3 solution is
mixed with a 100.0 mL sample of 0.200 M NaCl solution, the temperature in the
calorimeter rises to 25.30°C. Determine the ΔH。rxn for the reaction as written
below. Assume that the density and heat capacity of the solutions is the
same as that of water.
ΔH。rxn =?
A) -35 kJ
B) -69 kJ
C) -250 kJ
D) -16 kJ
E) -140 kJ
2)What pressure would a gas mixture in a 10.0 L tank exert if it were
composed of 48.5 g He and 94.6 g CO2 at 398 K?
A) 39.6 atm
B) 7.02 atm
C) 32.6 atm
D) 46.6 atm
E) 58.7 atm
3) According to the following reaction, what amount of Al2O3 remains when
20.00 g of Al2O3 and 2.00 g of H2O are reacted? A few of the molar masses
are as follows: Al2O3 = 101.96 g/mol, H2O = 18.02 g/mol.
A) 28.33 g
B) 14.00 g
C) 8.33 g
D) 19.78 g
E) 11.67 g
Thanks!!!
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1F：推 ellenroy:第三题题目没打错吗?哪里需要Al2S3分子量? 05/19 22:57
※ 编辑: finalpoet 来自: 203.71.94.31 (05/19 23:18)
2F：→ finalpoet:已修正了，谢谢 05/19 23:18
3F：推 cen71:第一题算不出来耶~我怎麽算都是59.63KJ 05/19 23:55
4F：→ cen71:第二题是46.6 用PV=nRT算出两个P 在相加得解 05/19 23:59
5F：→ cen71:第三题氧化铝应该是不溶於水~我可能会选D吧 用猜的>< 05/20 00:01
6F：→ finalpoet:59.63KJ怎麽算出来的阿?第二题感谢罗 05/20 19:01
7F：→ finalpoet:第三题我觉得是：Al2O3+6H2O→2Al(OH)3+3H2O 05/20 19:04
8F：推 cen71:如果第三题反应式如上，那剩余应该是18.1g的氧化铝 05/20 19:35
9F：→ cen71:第一题的话..反应系数比为1:1 然後从给的体积跟浓度可求mol 05/20 19:38
10F：→ cen71:两个mol数分别为 0.01跟0.02 所以AgNO3是限量 05/20 19:38
11F：→ cen71:然後用E=(Cc+ms)*ΔT ms为溶液重跟比热 题目说跟水一样 05/20 19:41
12F：→ cen71:所以ms代 m = 200g (200ml的溶液密度为1) s = 4.18 J/gC 05/20 19:42
13F：→ cen71:可以算出E= (15.5 + (200*4.18))*0.07 =59.605 为0.01mol反 05/20 19:44
14F：→ cen71:应热 所以标准反应焓应为 59.605 / 0.01 =5960.5J =59.6KJ 05/20 19:45
15F：→ cen71:我不知道我的想法对不对..不过跟答案不一样是真的 = = 05/20 19:47
16F：推 cen71:第三题的话就算出两个mol数 分别为0.196 跟 0.111 05/20 19:52
17F：→ cen71:而6mol的水跟1mol的氧化铝作用 所以0.111/6 = 反应的氧化铝 05/20 19:53
18F：→ cen71:的mol数 用0.196 - (0.111/6) 得剩余的氧化铝mol数 05/20 19:54
19F：→ cen71:再反算回去就可以求得剩余氧化铝的克数 05/20 19:55
20F：→ a12henry:反应应该不是长那样 要放硷在里面才会变成Al(OH)3 05/20 22:40
21F：→ finalpoet:感谢C大的解题，所以第三题的条件下是无法反应的罗 05/21 08:53
22F：推 cen71:依溶解度法则..Al2O3是不溶 应该把他当难溶 D的机会比较大 05/21 14:08