820 ! природний складається з двох нуклідів 63сu та 65сu. відносна атомна маса становить 63,55. обчисліть масову частку 63сu у природній міді. дайте відповідь з точністю до десятих у відсотках.
It is difficult to imagine our life without shopping. On one hand, it’s one of quite important household tasks. Moreover, shopping is the way to get necessary food and clothes. So, if you don’t do it you can’t have all things which make your life so comfortable.
On the other hand, it’s believed that for the vast majority of people going shopping is not just duty or necessity but a real pleasure. As far as I know there is so called shopping therapy that helps people to reduce stress buying different goods or even just going window shopping.
As for me, I don’t belong to such group of people. Shopping doesn’t make me happy and sometimes it can even become a nightmare. When I can’t find things which I need, I can get annoyed and even stressed. Thus, I go shopping only when I don’t have any other choices. I usually go to a supermarket to buy some food once or twice a week. There is a huge shopping center near my house, so I can buy everything I need in one place. From time to time when I need something urgently I can look in a local shop nearby. I normally go shopping alone, that’s why I can do it quickly and effectively. I always make a shopping list before going.
Nowadays it’s becoming more and more popular to shop online. I’m firmly convinced that it’s the most comfortable way. You just surf the Internet and look through the enormous range of goods. Moreover, you can compare prices and find a real bargain. Also, you can have your purchases delivered. It’s amazingly easy and saves a lot of time and energy.
Thus, if you’re not a fan of shopping like me, do it online.
Допустим воды для растворения много. Тогда нерастворимый осадок 3,5 г это карбонат кальция. Значит сразу считаем его процент 3,5/10 = 0,35 или 35%. Идем дальше. Пишем обе возможные реакции. CaCO3 = CaO + CO2 2NaHCO3 = Na2CO3 + H2O + CO2 (или проще для расчетов будет записать Na2CO3 + H2CO3). Если есть 20 г смеси, то в ней 20*0,35 = 7 грамм нашего карбоната, а значит 7/100 = 0,07 моль. Столько же моль и углекислого газа, который выделяется при его разложении, а значит масса газа = 0,07*44 = 3,08 г. Вычитаем эту цифру из 5,2-3,08 = 2,12 грамма, а это и есть наша H2CO3. Считаем количество угольной кислоты 2,12/62 = 0,034 моль. По реакции Na2CO3 в 2 раза больше = 0,068. Считаем массу NaHCO3 0,068*84 = 5,712 грамм. Считаем массу BaCl2 20-(7+5.712) = 7.288 грамма. Ну и дело за процентами CaCO3 = 35% NaHCO3 = 5.712/20 ≈ 0.29 или 29% BaCl2 = 7.288/20 ≈ 0.36 или 36%
It is difficult to imagine our life without shopping. On one hand, it’s one of quite important household tasks. Moreover, shopping is the way to get necessary food and clothes. So, if you don’t do it you can’t have all things which make your life so comfortable.
On the other hand, it’s believed that for the vast majority of people going shopping is not just duty or necessity but a real pleasure. As far as I know there is so called shopping therapy that helps people to reduce stress buying different goods or even just going window shopping.
As for me, I don’t belong to such group of people. Shopping doesn’t make me happy and sometimes it can even become a nightmare. When I can’t find things which I need, I can get annoyed and even stressed. Thus, I go shopping only when I don’t have any other choices. I usually go to a supermarket to buy some food once or twice a week. There is a huge shopping center near my house, so I can buy everything I need in one place. From time to time when I need something urgently I can look in a local shop nearby. I normally go shopping alone, that’s why I can do it quickly and effectively. I always make a shopping list before going.
Nowadays it’s becoming more and more popular to shop online. I’m firmly convinced that it’s the most comfortable way. You just surf the Internet and look through the enormous range of goods. Moreover, you can compare prices and find a real bargain. Also, you can have your purchases delivered. It’s amazingly easy and saves a lot of time and energy.
Thus, if you’re not a fan of shopping like me, do it online.
Идем дальше. Пишем обе возможные реакции.
CaCO3 = CaO + CO2
2NaHCO3 = Na2CO3 + H2O + CO2 (или проще для расчетов будет записать Na2CO3 + H2CO3).
Если есть 20 г смеси, то в ней 20*0,35 = 7 грамм нашего карбоната, а значит 7/100 = 0,07 моль. Столько же моль и углекислого газа, который выделяется при его разложении, а значит масса газа = 0,07*44 = 3,08 г.
Вычитаем эту цифру из 5,2-3,08 = 2,12 грамма, а это и есть наша H2CO3. Считаем количество угольной кислоты 2,12/62 = 0,034 моль. По реакции Na2CO3 в 2 раза больше = 0,068. Считаем массу NaHCO3 0,068*84 = 5,712 грамм. Считаем массу BaCl2 20-(7+5.712) = 7.288 грамма.
Ну и дело за процентами
CaCO3 = 35%
NaHCO3 = 5.712/20 ≈ 0.29 или 29%
BaCl2 = 7.288/20 ≈ 0.36 или 36%