Предмет: Химия, автор: Haseki07

Окислительно-восстановительные реакции
ZnO+Al=Al2O3+Zn.
Как решить помогите пожалуйста!

Ответы

Автор ответа: 1ndiraa

1

до реакции у цинка степень окисления +2 у кислорода-2 у алюминия +3

после реакции у цинка степень окисления 0 у алюминия +3 у кислорода -2

с.о поменял только цинк т.к у него было +2 стало 0 значит он принял два электрона и стал нейтральным. цинк является окислителем

3ZnO+2Al=Al2O3+3Zn (при подставлении коэффициентов уравнение становится равным)

svin99: Ответ неверный!!!!!

1ndiraa: что именно неверно?

svin99: Не бывает такого, чтоб с.о. менял только один элемент, чтоб был только окислитель, и не было восстановителя! Цинк приял 2 электрона - а откуда он их взял??? У алюминия с.о. до реакции - НОЛЬ, а не +3!!! Он отдаёт три электрона, окисляется - восстановитель!!!

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Shaw Wrote a Play

Once a poor flower-girl, quite by chance, overheard a conversation between two gentlemen. One of the gentlemen was a professor of phonetics. He was saying to the other that he could teach an uneducated person to speak good English. The girl was very much interested in what they were talking about. She tried to hear every word.
The fact was that she had for a long time been thinking of learning to speak correctly, and now she saw an excellent chance for herself. If she improved her manner of speaking the owners of the big flower shop would give her a job. She asked the two gentlemen to buy a few flowers from her and tried to speak to there but they didn't listen to her and soon went away.
The next day the girl came to the professor's house and asked him to give her lessons. The professor was very much surprised. At first he refused to teach her, saying that it was no use even trying, but then he agreed.
The results of the first lesson were poor. She couldn't produce proper English sounds and was tired of endless exercises. But soon the processor discovered that she was a clever girl. She took a great interest in her lessons and never missed a chance of practicing the sounds. As a result, her English became so good that the people who met her thought that she was a real lady.
The story of the girl can be found in one of Bernard Shaw's most popular plays.
___________________
to refuse - отказывать
proper – правильные

I. The text is about ...
1) a poor girl who worked hard at her English.
2) the work of the professor of phonetics.
3) the lilt of the rich gentleman.
4) the work of the flower-girl.

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2) learn where the two gentlemen lived.
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4) give phonetics lessons.

III. Find the wrong statement.
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