Реакция: 2AgNO3 + Zn = 2Ag + Zn(NO3)2
Увеличение массы пластины на 2 г (20 -18=2) обусловлено как переходом части цинка в раствор, так и выделением на ней серебра. Если примем за Х количество растворившегося цинка, можно составить уравнение:
2X*108 - X*65 = 2, или 151Х = 2, откуда Х=0,0132 моль.
Количество нитрата серебра в исходном растворе - вдвое больше, т. е. 0,0264 моль. Масса нитрата серебра:
m(AgNO3) = n*M = 0,0264 моль*170 г/моль = 4,5 г
Массовая доля нитрата серебра в растворе:
w(AgNO3) = m(AgNO3)/m(р-ра) = 4,5 г/150 г = 0,03, или 3%
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.
