初三化学计算题专题练习题word版本
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初三化学计算
1、已知尿素的化学式为CO（NH2）2，则一个尿素分子中含有个原子；尿素的相对分子质量是；碳、氧、氢、氮四种元素的质量比为；氮元素的质量分数为（填计算式）100kg 尿素中含氮元素的质量为；某农田需2.8kg氮元素，则应施kg尿素。
2、某农田去年用了60
3 ]
3、人体中钙元素主要存在牙齿和骨骼中，以羟基
磷酸钙[Ca10（PO4）6（OH）2]形式存在，其相对分子质
量为1004，右图是小青同学收集的纯牛奶的包装说明
阅读答题：
①一盒牛奶中至少含钙克
②羟基磷酸钙[Ca10（PO4）6（OH）2]中钙元素的质
量分数为（保留0、1%）
③若人体每天需要0、6克钙，且这些钙有90%来
自牛奶，则一个人每天至少喝盒牛奶。
4、、20 kg含氧化铁80%的赤铁矿，可冶炼含杂质2%
5、已知氯酸钾与二氧化锰的混合物15、5克，加热膨胀完全反应后，剩余固体的质量为10、7克，求①生成氧气多少克，在标准状况下为多少升？②10、7克固体是什么，各多少克？（2KClO3 ==== 2KCl+3O2-↑）
6、把一根铁钉放入到一定质量的硫酸铜溶液中，过一会儿称量，质量增重0、8克，则有多少克铁参加反应？同时有多少克铜生成？
7、某同学用混有二氧化锰的高锰酸钾8克加热制取氧气，完全反应后剩佘固体的质量7、36克，则剩余固体中二氧化锰的质量是多少？
M n O2
8、我国规定在食盐中加入碘梭钾KIO3的方法补碘，已知食盐中加碘的量每千克食盐中含碘为0、035克，相当干每千克食盐中含多少克碘酸钾？
9、20克碳和氧化铜的混合物加热完全反应后，称量为15、6克，求原
混合物中碳与氧化铜的质量比。
10、将171克石灰石高温煅烧（杂质不含氧也不参加反应），待反应完全后测得残佘物中氧元素的质量减少了24克，求石灰石中碳酸钙的质量分数。
2014级单元测试（A卷）（Unit1-Unit2）
Ⅰ. Multiple Choices
1.Sara has made up her mind that her leisure interests will never ________ her career.
A.in the way of
B. get in the way of
C. get in way of
D. in way of
2.The rise in interest rate will be disastrous ________ small firms.
A.in case of
B. in the case of
C. reckon with
D. in case
3.He ________ his time until Harvard University offered him a professorship.
A.bided
B. equipped
C. launched
D. engaged
4.By a ________ of good luck, Genelle, who had been buried in the rubble for more than 26 hours,
came out alive.
A.struck
B. stroke
C. stick
D. strike
5.If you let yourself ________ bogged down in paper work, you’ll never find time to deal with the
really important issues.
A.step
B. involve
C. get
D. set
6.Despite difficulties, the government ________ on with its campaign to eliminate corruption.
A.stressed
B. launched
C. offended
D. pressed
7.These compensation cases have already ________ on for over a year.
A.pressed
B. pushed
C. dragged
D. retreated
8.The local government developed its economy but ________ the environment.
A.in honor of
B. at the cost of
C. for the sake of
D. at a loss
9.How often do you think celebrities ________ charity work out of the goodness of their heart, not
publicity?
A.engage in
B. engage on
C. engage for
D. engage at
10.On October 4, 1957, Soviet scientists ________ the world’s first artificial satellite, called Sputnik.
A.conquered
B. started
C. launched
D. retreated
11.We all have stress, but if you don’t do something to relieve it, sooner or later it will ________.
A.take its role
B. pay the cost
C. take its toll
D. pay the toll
12.He urges potential informants not to ________ the importance of any piece of information they can
gather.
A.A. estimate
B. overestimate
C. underestimate
D. overstate
13.In the US, the word 'oriental' is considered ________ to Asians because the term is based on the
geographic relationship of Asia from a Western perspective.
A. defend
B. defensive
C. offend
D. offensive
14.He said it was important to observe, monitor, ________ and if necessary, correct those training in
care.
A. instruct
B. engage
C. order
D. teach
15.The total ________ count may not be particularly high considering China's huge population.。
