问题 问答题 简答题

SO2转化为什么要使用钒触媒?

答案

参考答案:平衡转化率要求反应温度低,而反应速度要求反应温度高,钒触媒的主要作用是它能与反应物分子结合,形成过渡性的“表面中间化合物”,然后再分解得到生成物和触媒。反应物与触媒形成过渡性的“表面中间化合物”的反应,两者需要的活化能都比反应物直接反应成生成物的活化能小得多,这样触媒虽然参加了反应,却没有进入产品,实际上只是使反应沿着一条活化能小的途径进行。因而,在同样温度条件下,反应速度大大加快。钒触媒解决了平衡转化率和反应速度对温度要求的矛盾。使过程能实现工业生产。这就是为什么二氧化硫转化必须采用触媒的原因。

判断题
单项选择题

The Man of Many Secrets—Harry Houdini—was one of the greatest American entertainers in the theater next century. He was a man famous for his escapes—from prison cells, from wooden boxes floating in rivers, from locked tanks full of water. He appeared in theaters all over Europe and America. Crowds came to see the great Houdini and his "magic" tricks.

Of course, his secret was not magic, or supernatural powers. It was simply strength. He had the ability to move his toes as well as he moved his fingers. He could move his body into almost any position he wanted.

Houdini started working in the entertainment world when he was 17, in 1891. He and his brother Theo performed card tricks in club in New York. They called themselves the Houdini Brothers. When Harry married in 1894, he and his wife Bess worked together as magician and assistant. But for a long time they were not very successful. Then Harry performed his first prison escape, in Chicago in 1898. Harry persuaded a detective to let him try to escape from the prison, and he invited the local newspapermen to watch.

It was the publicity that came from this that started Harry Houdini’s success. Harry had fingers trained to escape from handcuffs and toes trained to escape ankle chins. But his biggest secret was how he unlocked the prison doors. Every time he went into the prison cell, Bess gave him a kiss for good luck—and a small skeleton key, which is a key that fits many locks, pass quickly from her mouth to his.

Harry used these prison escapes to build his fame. He arranged to escape from the local prison of every town he visited. In the afternoon, the people of the town would read about it in their local newspapers, and in the evening every seat in the local theater would be full. What was the result World-wild fame, and a name remembered today.

Which of the following is the best title for the passage()

A. A Skeleton Key

B. A Man of Many Secrets

C. World-wild Fame

D. Great Escape