Процесс разложения нитрата аммония может протекать по двум схемам:
1) nh4no3 (т) = n2o (г) + 2h2o (г)
2) nh4no3 (т) = n2 (г) + 1/202 (г) + 2h2o (г)
определите, какая из двух реакций более экзотермична и термодинамически более вероятна при т= 298к ? в какой реакции возрастание энтропии системы больше ?
1) The official name of Great Britain is The United Kingdom of Great Britain and Northern Ireland.
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.
6) The surface of Great Britain varies greatly. The northern and western parts of the country is mountainous and is called the Highlands.
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.
8) The climate of the British Isles is milder than that of the Continent because the mountains, the Atlantic Ocean and the warm waters of the Gulf Stream influence the climate of Great Britain.
9) Yes, it is. Great Britain is a highly developed industrial country.
10) The British industry produce iron and steel products, machinery and electronics, chemicals and textile, aircraft and navigation equipment.
11) London, Birmingham, Manchester, Leeds, Liverpool, Glasgowand Bristol are ndustrial cities in Great Britain.
12)I know many outstanding people of Great Britain, for example, sir Winston Churchill, Margaret Thatcher, writers Shakespeare, Swift, Doyle, Milne, Stephenson, Tolkien; people like Martin Luther King, George Washington, Abraham Lincoln and many others.
13)There are such big educational establishments in Great Britain as Oxford and Cambridge universities.
14) No, it isn't. The United Kingdom is a monarchy.
15)The name of the Queen of Great Britain is Elisabeth II.
16) Yes, her power is limited by Parkiament.
17)The British Parliament consist of two chambers: the House of Lords and the House of Commons.
18) The Labour, the Conservative and the Liberal parties are the main political parties in Great Britain.
19)The Prime Minister of Great Britain is Antony Blair.
20) He is the head of The Labour party.
S = 25г/100г н₂о
mдоб. = 8 г
mк.г. = 32 г
Найти: w(с/к.г).
Решение:
1) Переведем растворимость S в массовые доли wнас.
Если 25 г растворяется в 100 г воды, то wнас. = 25/(25+100) = 0,2
2) Добавили 8 г соли и нагрели.
Пусть у нас было m г насыщенного раствора с wнас=0,2, тогда соли в нем было 0,2m
После добавления и нагревания стало: (0,2m+8) г соли
в (m+ 8) г горячего раствора.
3) После охлаждения до прежней температуры выпало 32 г кристаллогидрата.
Пусть безводной соли в кристаллогидрате содержится w(с/к.г), тогда:
w(c/к.г.)*32 г масса безводной соли в выпавшем кристаллогидрате.
(0,2m + 8 - w(с/к.г)*32) г осталось соли в насыщенном растворе
(m + 8 - 32) = (m - 24) г осталось раствора
4). Поскольку раствор охладили до той же температуры, при которой растворимость (и массовая доля растворенной соли) прежняя, составим и решим уравнение:
0,2 = (0,2m + 8 - w(с/к.г.)*32)/(m-24)
0,2m - 4,8 = 0,2m + 8 - w(с/к.г.)*32
w(с/к.г)*32 = 12,8
w(с/к.г.) = 12,8/32 = 0,4 = 40 %
ответ: 0,4 (или 40%) массовая доля безводной соли в выпавшем кристаллогидрате.