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问题 填空题

室温下将6g CH3COOH溶于水配制成1L的溶液，此溶液的物质的量浓度为______，经测定溶液中含CH3COO-浓度为1.4×10-3mol/L，醋酸的电离度为______，醋酸的电离平衡常数为______，此时溶液中由水电离出的c（H+）与c（OH-）之积______（填“大于”、“小于”或“等于”）1.0×l0-14．加入硝酸铵后醋酸的电离度______（填“增大”或“减小”或“不变”）．醋酸的电离平衡常数______ （填“增大”或“减小”或“不变”）．

答案

n（CH3COOH）=

6g
60g/mol
=0.1mol，

c（CH3COOH）=

0.1mol
1L
=0.1mol/L，

α=

c(CH3COO-)
c(CH3COOH)
×100%=
1.4×10-3
0.1
×100%=1.4%，

k=

c(CH3COO-)×c(H+)
c(CH3COOH)
=
1.4×10-3×1.4×10-3
0.1-1.4×10-3
=1.99×10-5，

醋酸抑制水的电离，溶液中由水电离出的c（H+）与c（OH-）之积小于1.0×l0-14，

加入硝酸铵后，CH3COO-浓度增大，抑制醋酸的电离，醋酸的电离度减小，

醋酸的电离平衡常数只受温度的影响，温度不变，平衡常数不变，

故答案为：0.1mol/L；1.4%；1.99×10-5；小于；减小；不变．

单项选择题

pBR322是（）

A.经人工改造的大肠埃希菌质粒

B.天然的酵母质粒

C.天然的大肠埃希菌质粒

D.经人工改造的噬菌体

E.经人工改造的酵母质粒
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单项选择题

Research on animal intelligence always makes me wonder just how smart humans are. (51) the fruit-fly experiments described in Carl Zimmer’s piece in the Science Times on Tuesday. Fruit flies who were taught to be smarter than the average fruit fly (52) to live shorter lives. This suggests that (53) bulbs burn longer, that there is an advantage in not being too terrifically bright.

Intelligence, it (54) , is a high-priced option. It takes more upkeep, burns more fuel and is slow off the starting line because it depends on learning—a (55) process—instead of instinct. Plenty of other species are able to learn, and one of the things they’ve apparently learned is when to (56) .

Is there an adaptive value to (57) intelligence That’s the question behind this new research. I like it. Instead of casting a wistful glance (58) at all the species we’ve left in the dust I.Q.-wise, it implicitly asks what the real (59) of our own intelligence might be. This is on the mind of every animal I’ve ever met.

Research on animal intelligence also makes me wonder what experiments animals would (60) on humans if they had the chance.

54().

A. insists on

B. sums up

C. turns out

D. puts forward
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