问题 问答题 论述题

为什么要控制电解液的质量标准和范围?

答案

参考答案:

电解质氢氧化钾或氢氧化钠的纯度直接影响到电解后所产生气体的品质和对设备的腐蚀。当电解液中含有碳酸盐和氯化物时,会在阳极上发生下列反应:

2CO-4e→2CO2↑+O2↑(可逆)

2Cl-2eCl2

种反应不但消耗了电能,而且因氧气中混入氯气而降低其纯度。同时生成的二氧化碳立即又被碱液吸收,并还原成碳酸钠,导致其CO2-3的放电反应反复进行下去,白白消耗大量电能。另外,反应生成的氯气,也能与碱液反应生成次氯酸钠和氯化钠,又有在阴极被还原的可能,也要消耗吸收电能,所以要控制电解质标准在一定范围内。

阅读理解

An old man called Xie Liang, 80, has given free help to people who ask for directions for 8 years.

Every day, Mr Xie goes to Dongzhimen Bus Stop, and gives help to at least 1,200 people asking for directions. During holidays, the number may be even 3,500. There are more than 50 roads and streets meeting at Dongzhimen, and at least 100 thousand people pass by there daily.

The reporter of Beijing Youth Daily had an interview with Xie. At that time, he arrived at the bus stop and placed his little table with maps and guidebooks written by himself on it.

"Is it really free to ask you for the way?" said a person from southeast China

"Of course," answered Xie with a smile. "Quite a number of people have asked me the same question. I am a volunteer."

The reporter found that at least 5 people came to ask him for the way in a minute, and Xie told them the way patiently and gave every one of them a note with his words on it.Xie has a husky voice. People think that it's because of the result of the things he is doing.

Now Xie has encouraged several other volunteers to join him. Many people hope to do volunteering like Xie, but it's hard to do as well as he does.

小题1:Xie Lang directs the ways for people at the bus stop as         .

A.a driver

B.a reporter

C.a guide

D.a volunteer小题2:During holidays, there may be ________ people a day asking Xie for ways.

A.5

B.1,200

C.3,500

D.100,000小题3:The old man helps others by       .

A.calling a taxi for them

B.driving them to the right place

C.giving them maps or guidebooks to read by themselves.

D.telling them the right way or writing the way on a note.小题4:Which of the following is NOT TRUE according to the passage?

A.No other volunteers help Xie Liang now.

B.Xie Liang has written some guidebooks on his own.

C.People don’t need to pay Xie Liang for asking for directions.

D.Xie Liang’s voice is bad because he has to talk with so many people every day.

多项选择题