Задания 3 Рассчитайте молярную массу газа, если его плотность по азоту 2,537, по гелию 17,75
Задания 4
(а) Используя закон объёмных отношений рассчитайте:
объем водорода который необходим для получения 18 л аммиака (NH3) H2+N2=NH3
(b) объем кислорода который прореагирует с 30 л водорода H2+O2=H2O

Дано:
m(смеси)=31,9 г
m(H₂O)=9 г
Найти:
w(Fe₂O₃)-?
w(CuO)-?

Решение:
1) Fe₂O₃+3H₂=2Fe+3H₂O
2) CuO+H₂=Cu+H₂O
Найдем общее количество вещества воды в обеих реакциях:
моль
Пусть количество вещества Fe₂O₃ будет х моль, тогда воды в 1 реакции образуется 3х моль; пусть количество вещества CuO будет у моль, тогда воды во 2 реакции будет у моль
Масса Fe₂O₃ равна 160х г, а масса CuO равна 80у г. Количество вещества воды равно (3х+у) моль
Составим систему уравнений:

Выразим у


Решим первое уравнение


моль (это количество вещества Fe₂O₃)
Найдем у:
у=0,5-3*0,10125=0,19625 моль (это количество вещества CuO)
Найдем массу Fe₂O₃:
г
Найдем массу CuO:
г
Найдем массовую долю Fe₂O₃:
или 50,78% (где m(X) - это масса смеси)
Найдем массовую долю CuO:
или 49,22%
ответ: w(Fe₂O₃)=50,78%; w(CuO)=49,22%

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2) The UK is situated on the British Isles.

3) It consists of four parts: England, Wales, Scotland and Northern Ireland.

4) The territory of the United Kingdom is about 244,000 square kilometres. The population of the United Kingdom is more than 57 million people.

5) London is the capital of the UK.

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7) There are no long rivers. The most important of them are the Severn, the Thames, the Trent . There are many beautiful lakes in the mountainous parts of the country.

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17)The British Parliament consist of two chambers: the House of Lords and the House of Commons.

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19)The Prime Minister of Great Britain is Antony Blair.

20) He is the head of The Labour party.