Вопрос школьника по предмету Химия
Масса 20%-го раствора гидроксида натрия, которая может вступить во взаимодействие с 15 г аминоуксусной кислоты , равна _______ г. ( Запишите число с точностью до целых )
Распишите всё пожалуйста подробно (т.е. с формулами и с дано/решением)
Ответ учителя по предмету Химия
w=0,2 (20%) массовая доля гидроксида натрия в растворе
m(H₂NCH₂COOH)=15 г
m(p)-? масса раствора
реакция
H₂NCH₂COOH + NaOH = H₂NCH₂COONa + H₂O
по уравнению реакции
m(H₂NCH₂COOH)/M(H₂NCH₂COOH)=m(NaOH)/M(NaOH)
откуда (1)
m(NaOH)=M(NaOH)m(H₂NCH₂COOH)/M(H₂NCH₂COOH)
также
m(NaOH)=m(p)w (2)
подставляем выражение (2) в (1)
m(p)w=M(NaOH)m(H₂NCH₂COOH)/M(H₂NCH₂COOH)
m(p)=M(NaOH)m(H₂NCH₂COOH)/(wM(H₂NCH₂COOH))
m(p)=40г/моль*15г/(0,2*75г/моль)=40 г (масса 20%-го раствора гидроксида натрия)
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The «Jolly Roger» is the well-known pirate flag. There are a number of theories about its origin. It is thought that the first pirates used a red flag, which was common in sea attacks. A red flag told other ships that there would be no pity and no prisoners would be taken. This red flag was called Joli Rouge (pretty red) in French. Most probably, English people pronounced it in their own way «Jolly Roger». Another theory says that «old Roger» was another name for the devil.
Another popular image from the pirate world is a parrot, sitting on the captain’s shoulder. Well, there’s no historical proof of that. No doubt, pirates often travelled to faraway exotic lands and brought unusual animals as souvenirs with them. Parrots were particularly popular because they were colourful, could be taught to speak, and were easier to care for than, say, monkeys. However, you can’t imagine a pirate fighting with a bird on the shoulder. This image possibly began with the book ‘Treasure Island’. In the book, the ever famous Long John Silver carried a parrot as a pet.
Before joining a ship each pirate signed an agreement called «Articles». This explained the rights and laws on board the ship, how much a person was paid, what to do in case of emergency, etc. For example, playing cards for money was not allowed. For breaking the rules a pirate would be shot or left on a desert island with a bottle of water and a gun.
A pirate ship was organized democratically. After a successful attack they divided the treasures equally, only the captain and the cook got more. They sometimes decided together which ship to attack or where to sail next. Most pirates were paid four times more than they had when they were sailors. But on land they were criminals and lots of money was offered to those who caught them.
However, for some time the English government supported pirates. There were lots of pirates in the sixteenth century when England was at war with Spain and the Dutch Republic. Queen Elizabeth I ordered them to rob Spanish ships and bring gold, silver and jewels to the country. Sir Francis Drake was one of the most famous pirates. He brought lots of treasures to England and also was the first Englishman to sail all the way around the world. Because of this, he was made a knight by Queen Elizabeth I.
1.Professional sailors never became pirates.
2.The flag «Jolly Roger» meant death for ships’ sailors and passengers.
3.The name for the flag «Jolly Roger» is of English origin.
4.Parrots brought luck to pirates at sea.
5.»Articles» regulated pirates’ behaviour at sea.
6.After the attack the captain took all the treasures.
7.In the past pirates did some jobs for English queens and kings.
8. Francis Drake was the richest English pirate
Указать где True/False/ Not stated