(1)化学反应可视为旧键断裂和新键形成的过程,化学键的键能是形成(或拆开)1mo

题型:填空题

问题:

(1)化学反应可视为旧键断裂和新键形成的过程,化学键的键能是形成(或拆开)1mol化学键时释放(或吸收)的能量.已知:N≡N键的键能是948.9kJ•mol-1,H-H键的键能是436.0kJ•mol-1;由N2和H2合成1molNH3时可放出46.2kJ的热量.N-H键的键能是______.

(2)盖斯定律在生产和科学研究中有很重要的意义.有些反应的反应热虽然无法直接测得,但可通过间接的方法测定.现根据下 * * 个热化学反应方程式:

Fe2O3(s)+3CO(g)=2Fe(s)+3CO2(g)△H=-24.8kJ•mol-1

3Fe2O3(s)+CO(g)═2Fe3O4(s)+CO2(g)△H=-47.2kJ•mol-1

Fe3O4(s)+CO(g)═3FeO(s)+CO2(g)△H=+640.5kJ•mol-1

写出CO气体还原FeO固体得到Fe 固体和CO2气体的热化学反应方程式:______.

考点:盖斯定律化学反应热的计算
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下列选项中,不是期货交易流程中的必经环节的是()。

A.交割

B.开户

C.下单

D.竞价

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If you dream of going someplace warm to escape the cold winter weather,a trip to a recently discovered planet would certainly warm you right up.The planet,named

OGLE-TR-56b,has temperatures of more than 3,000°F.“This is the hottest planet we know about,”says Dr Dimitar Sasselov,a scientist who led the discovery team.“It is hot enough to have an iron fog and to rain hot iron droplets(细沫).”

The new planet is 30 times farther away than any planet discovered by scientists

before.It is in the Milky Way(银河)but it is not in our solar(太阳的)system.The new planet moves around a star much like our sun,however scientists discovered the planet by using a new planetsearching method called transit technique.They were able to catch sight of the planet when it moved in front of its star,causing the star's light to dim(变暗).Scientists compare the method to discovering the shadow of a bee flying in front of a searchlight 200 miles away.“We believe the door has been opened wide to go and discover planets like the Earth,”says Sasselov.

1.We can infer from the passage that_________.

A.there is iron on the new planet

B.we could go to the new planet in winter

C.the star could block our view of the new planet

D.scientists are studying the weather

2.The “transit technique”can_____________.

A.help dim the light of a star

B.help scientists with a searchlight

C.help discover a bee on a planet

D.help find a planet moving before its star

3.Which is the best title for the passage?

A.New Planet searching Technique

B.New Distant Discovery

C.Space Searching

D.Dream Planet

题型:填空题

如图所示的工具或仪器中属于省力杠杆的是[ ]

A.

B.

C.

D.

题型:填空题

2004年,学生报到时间是()

A、2月6日

B、2月7日

C、2月8日

题型:填空题

CODcR测定仪工作中首先由自吸泵将水样从排放明渠提升至()。

A.反应室

B.测量室

C.精滤采样被

D.粗滤桶

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