Предмет: Химия, автор: GelyaButterfly

Вычислить массовую долю алюминия в его оксиде

Ответы

Автор ответа: Аэроплан

Решение во вложении:

................................

Приложения:

Автор ответа: ромчикааа

Оксид алюминия - Al2O3
Молярная масса = 102 г/моль
масса, приходящаяся на алюминий из этой молярной, соответственно 27*2 = 54 г/моль
массовая доля алюминия W% (Al) = (54 : 102)*100% =~ 52.9 % (53%)

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Ecology is a science which studies the relationship between all forms of life on our planet and the environment. Since ancient times Nature has served Man, giving him everything he needs: air to breathe, food to eat, water to drink, wood for building and fuel for heating his home. For thousands of years people lived in harmony with the environment and it seemed to them that the resources of Nature had no end or limit. With the industrial revolution our negative influence on Nature began to increase. Large cities with thousands of polluting plants and factories can be found nowadays all over the world. They pollute the air we breathe, the water we drink, the fields where our crops are grown. Big cities suffer from smog. Cars with their engines have become the main source of polluting in industrial countries. Vast forests are cut down everywhere for the needs of industries. As a result many kinds of animals, birds, fish and plants are disappearing nowadays. The pollution of the air and the world’s oceans and the thinning the ozone layer are the other problems arising from men’s careless attitude to ecology. Active measures should be taken to save the life on our planet. There is an international organization called Greenpeace which is doing much to preserve the environment.

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2Plants and factories don’t pollute the air, the water, the fields.
3Vast forests are cut down for the needs of industries.
4Big cities suffer from smog.
5Many kinds of animals, birds,
fish and plants are appearing nowadays.
6Greenpeace is an international organization which is doing much to preserve the environment.