Dear,Max
Greetings from England.We're having great time here.The museums is very interesting.We are lucky with the weather.The sunshine everyday,but it's not very hot.Yesterday we had a cool day!We saw Big Ben!It's very long!
It's very beautiful here!We was in forest,we was in cafe.In cafe I ate pasta!
Write to me soon.
Take care,
Alex
Дано:
m в-ва=15 г
m(H2O)=200 г
_______________
W-?
W=m в-ва/m р-ра *100%
m р-ра=200+15=215 г
W=15/215*100%=6.98%
Дано масса 4 р 11 ты 11:4~мыс 48,36,23
Прокипятить. Выше 90С гидрокарбонат разлагается:
2NaHCO3 -> Na2CO3 + H2O + CO2 (газ)