搜题请搜索小程序“爱下问搜题”
问题 问答题

现有200mL 1mol/L H2SO4溶液，回答下列问题：

（1）写出H2SO4的电离方程式______

（2）该H2SO4溶液中H+的物质的量浓度是______

（3）请设计一个实验方案，证明此溶液中含有H+和SO42-离子：

（4）用此H2SO4溶液和足量金属Zn反应，可以得到标准状况下气体多少升？

答案

（1）硫酸为二元强酸，完全电离，电离方程式为H2SO4═2H++SO42-，故答案为：H2SO4═2H++SO42-；

（2）硫酸为二元强酸，c（H+）=2c（H2SO4）=2×1mol/L=2mol/L，故答案为：2mol/L；

（3）检验H+可用酸碱指示剂，检验SO42-可用盐酸酸化的氯化钡溶液，如果溶液变红，说明有H+，有白色沉淀生成，说明有SO42-，

答：分别取少量试液与试管中，分别加入紫色石蕊试液和盐酸酸化的氯化钡溶液，如果溶液变红，说明有H+，有白色沉淀生成，说明有SO42-；

（4）硫酸的物质的量为：0.2L×1mol/L=0.2mol，设生成xL氢气，则

Zn+H2SO4=ZnSO4+H2↑

    1mol      22.4L

     0.2mol    xL

x=4.48，

答：可以得到标准状况下气体4.48L．

完形填空

Directions: Complete the following passage by filling in each blank with one word that best fits the context.

Lazy people are often seen as useless. However, are they really being lazy   小题1:  are they acting lazy? There is a huge difference between saying you act lazy sometimes and you are a lazy person.

So   小题2:  causes a person to be inactive? The answer is   小题3:  lack of goals and purpose. If you give someone a good enough reason to do something, they will do it. People   小题4:  don’t seem to do anything just haven’t found a good enough reason to do anything. Lazy students don’t study because they don’t see the point in studying. If you give them a reason, a strong enough reason that is, they will take action. For example, if you are   小题5:  lazy to go to the gym, would you go if someone offered you a million dollars to go? If you are too lazy to clean out the garage, would someone pointing a gun to your head help you take action? The reason can be positive or negative as long as   小题6:  is strong enough to induce(引起) action.

Action will lead to success while inaction will lead to failure. 小题7:  you take action though, you need a compelling reason to do so.   小题8:  motivate someone who is lazy, what you need to do is help them find purpose and enough reasons to work towards a certain goal.

查看答案
单项选择题

从概念上划分，系统实施阶段有若干项彼此配合的同步工作，以下不属于这些工作的是（）。

A．设备安装

B．模块划分

C．程序编码

D．数据准备
查看答案