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Có hai dung dịch; H2SO4 (dung dịch A), và NaOH (dung dịch B). Trộn 0,2 lít dung dịch A với 0,3 lít dung dịch B được 0,5 lít dung dịch C. Lấy 20 ml dung dịch C, thêm một ít quì tím vào, thấy có màu xanh. Sau đó thêm từ từ dung dịch HCl 0,05M tới khi quì tím đổi thành màu tím thấy hết 40 ml dung dịch axit. Trộn 0,3 lít A với 0,2 lít B được 0,5 lít dung dịch D. Lấy 20 ml dung dịch D, thêm một ít quì tím vào thấy có màu đỏ. Sau...
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Có hai dung dịch; H2SO4 (dung dịch A), và NaOH (dung dịch B). Trộn 0,2 lít dung dịch A với 0,3 lít dung dịch B được 0,5 lít dung dịch C.

Lấy 20 ml dung dịch C, thêm một ít quì tím vào, thấy có màu xanh. Sau đó thêm từ từ dung dịch HCl 0,05M tới khi quì tím đổi thành màu tím thấy hết 40 ml dung dịch axit.

Trộn 0,3 lít A với 0,2 lít B được 0,5 lít dung dịch D. Lấy 20 ml dung dịch D, thêm một ít quì tím vào thấy có màu đỏ. Sau đó thêm từ từ dung dịch NaOH 0,1M tới khi quì tím đổi thành màu tím thấy hết 80 ml dung dịch NaOH.

a. Tính nồng độ mol/l của 2 dung dịch A và B.

b. Trộn VB lít dung dịch NaOH vào VA lít dung dịch H2SO4 ở trên ta thu được dung dịch E. Lấy V ml dung dịch E cho tác dụng với 100 ml dung dịch BaCl2 0,15 M được kết tủa F. Mặt khác lấy V ml dung dịch E cho tác dụng với 100 ml dung dịch AlCl3 1M được kết tủa G. Nung F hoặc G ở nhiệt độ cao đến khối lượng không đổi thì đều thu được 3,262gam chất rắn. Tính tỉ lệ VB:VA

1
10 tháng 3 2022

a. PTHH:

+ Lần thí nghiệm 1: 2NaOH + H2SO4  →  Na2SO4 + 2H2O          (1)

Vì quỳ tím hóa xanh, chứng tỏ NaOH dư. Thêm HCl: 

HCl + NaOH →  NaCl + H2O                        (2)  

+ Lần thí nghiệm 2: phản ứng (1) xảy ra, sau đó quỳ hóa đỏ chứng tỏ H2SO4 dư. Thêm NaOH: 

     2NaOH + H2SO4 → Na2SO4 + 2H2O (3) 

+ Đặt x, y lần lượt là nồng độ mol/l của dung dịch A và dd B: Từ (1),(2),(3) ta có:

0,3y - 2.0,2x = 0,05 (I)

0,3x - \(\dfrac{0,2y}{2}\) = 0,1 (II)

Giải hệ (I,II) ta được: x = 0,7 mol/l ,  y = 1,1 mol/l

b,  Vì dung dịch E tạo kết tủa với AlCl3 , chứng tỏ NaOH còn dư.

AlCl3 + 3NaOH →  Al(OH)3 + 3NaCl             (4)

2Al(OH)3 → Al2O3 + 3H2O                            (5)

Na2SO4 + BaCl2 →   BaSO4 + 2NaCl           (6)  

Ta có n(BaCl2) = 0,1.0,15 = 0,015 mol

n(BaSO4) = 3,262 : 233= 0,014 mol < 0,015 mol

⇒ n(H2SO4) = n(Na2SO4) = n(BaSO4) = 0,014 mol . Vậy VA = 0,014 : 0,7 = 0,02 lít

n(Al2O3) = 3,262 : 102 = 0,032 mol và n(AlCl3) = 0,1.1 = 0,1 mol.                      

+ Xét 2 trường hợp có thể xảy ra:

- Trường hợp 1: Sau phản ứng với H2SO4,NaOH dư nhưng  thiếu so vời AlCl3 (ở pư (4): n(NaOH) pư trung hoà axit = 2.0,014 = 0,028 mol

nNaOH pư (4) = 3n(Al(OH)3) = 6n(Al2O3) = 6.0,032 = 0,192 mol.

Tổng số mol NaOH bằng 0,028 + 0,192 = 0,22 mol

Thể tích dung dịch NaOH 1,1 mol/l là \(\dfrac{0,22}{1,1}\)= 0,2 lít . Tỉ lệ VB : VA = 0,2 : 0,02 = 10

- Trường hợp 2: Sau (4) NaOH vẫn dư và hoà tan một phần Al(OH)3:

Al(OH)3 + NaOH → NaAlO2 + 2H2O (7)

Tổng số mol NaOH pư (3,4,7) là: 0,028 + 3.0,1 + 0,1 - 2.0,032 = 0,364 mol

Thể tích dung dịch NaOH 1,1 mol/l là \(\dfrac{0,364}{1,1}\)= 0,33 lít

⇒ Tỉ lệ VB : VA = 0,33 : 0,02 = 16,5

10 tháng 3 2022

A: CaCO3

B: CO2

C: NaHCO3

D: Na2CO3

E: HCl

F: CaCl2

PTHH: 

\(CaCO_3\left(A\right)\underrightarrow{t^o}CaO+CO_2\left(B\right)\)

\(CO_2\left(B\right)+NaOH\rightarrow NaHCO_3\left(C\right)\)

\(CO_2\left(B\right)+2NaOH\rightarrow Na_2CO_3\left(D\right)+H_2O\)

\(NaHCO_3\left(C\right)+HCl\left(E\right)\rightarrow NaCl\left(H\right)+CO_2+H_2O\)

\(Na_2CO_3\left(D\right)+CaCl_2\left(F\right)\rightarrow2NaCl\left(H\right)+CaCO_3\downarrow\)

\(NaHCO_3\left(C\right)+NaOH\rightarrow Na_2CO_3\left(D\right)+H_2O\)

\(Na_2CO_3\left(D\right)+HCl\rightarrow NaCl+NaHCO_3\left(E\right)\)

\(n_{hh}=\dfrac{11,2}{22,4}=0,5mol\)

\(\left\{{}\begin{matrix}n_{C_2H_4}=x\left(mol\right)\\n_{C_2H_2}=y\left(mol\right)\end{matrix}\right.\Rightarrow x+y=0,5\left(1\right)\)

\(C_2H_4+Br_2\rightarrow C_2H_4Br_2\)

\(C_2H_2+2Br_2\rightarrow C_2H_2Br_4\)

\(\Rightarrow x+2y=0,7\left(2\right)\)

Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}x=0,3\\y=0,2\end{matrix}\right.\)

\(\%V_{C_2H_4}=\dfrac{0,3\cdot22,4}{11,2}\cdot100\%=60\%\)

\(\%V_{C_2H_2}=100\%-60\%=40\%\)

Choose the best option to complete each of the following sentences.  5. You can speak English fluently, __________?A. could youB. can’t you C. can you D. couldn’t you   6. On average, _________Moon is 384.400 km from ___________ Earth.A. the-theB. x-theC. a-an D. a-the  7. _________ my opinion, he is the best football player in our team.A. OnB. AtC. InD. From  8. On March 8th , women often _____ beautiful roses, postcards, lots of gifts with the best   wishes from their relatives and...
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Choose the best option to complete each of the following sentences.

  5. You can speak English fluently, __________?

A. could you

B. can’t you

C. can you

D. couldn’t you

  6. On average, _________Moon is 384.400 km from ___________ Earth.

A. the-the

B. x-the

C. a-an

D. a-the

  7. _________ my opinion, he is the best football player in our team.

A. On

B. At

C. In

D. From

  8. On March 8th , women often _____ beautiful roses, postcards, lots of gifts with the best   wishes from their relatives and friends.

A. give

B. send

C. have

D. receive

  9. The driver stopped ______ a coffee because he felt sleepy.

A. have

B. to have

C. having

D. had

  10. I wish I ______ play football well.

A. can

B. could

C. am

D. did

  11. If I ________ you, I would join this English Speaking Contest.

A. were

B. am

C. would be

D. will be

  12. _______ there is a lot of noise in the city, I like living there.

A. Because

B. Despite

C. In spite of

D. Although

  13. I suggest ________ a shotcut through the field . It will take much less time.

A. take

B. taking

C. to take

D. takes

  14. She has a lot of ___________ while she’s studying English.

A. difficult

B. difficulties

C. difficile

D. diffident

   15. He finds the way to a place easily. He was a very good sense of ___________

A. direction

B. humor

C. style

D. responsibility

16. There are lots of people who _____ work in remote and mountainous areas  nowadays.

A. volunteers

B. voluntary

C. voluntarily

D. volunteer

   17. If you want to _____ the other students in your class, you’ll have to work very hard.

A. catch up with

B. learn on

C. catch up

D. hurry up

 

  Mark the letter A, B,C or D to indicate the correct answer to each of the following        questions.

  18. -  Mary: “ Thank s for your help, John.”    

        - John:   “ ______________”

A. There’s nothing

C. It’s my pleasure

B. Nothing

D. It sounds good

   19. – Lan: “ Do you think Covid-19 is one of the most dangerous diseases?”

         -  Mai: “ ________________”

A. Well that’s very surprising

C. Not at all. Go ahead.

B. Sure. Thanks.

D. There’s no doubt about it.

   

  Choose one underlined part that is incorrect in each of the sentences.

   20. Some of the students seemed very nervously before the final exam.

             A                         B                                    C          D

   21. The number of students are not large, therefore, a number of tickets are available to   

               A                                      B                                                   C                                          D

   them.   

    22. You should take the raincoat with you in case it will rain hard this afternoon.

                                A                         B               C              D

    23. Her sister always runs more quickly as her.

                                A       B               C       D                   

    24. As soon as he completes his homework, he helps feed the chickens and collects the

                                     A                         B                                              C                 D

     eggs.

    Choose the sentence that is closest in meaning to each of the sentences given.

    25. My father often played football when he was young.

    A. My father used to play football when he is young.

    B. My father used to play football when he was young.

    C. My father used to playing football when he was young.

    D. My father used to playing football when he be young.

    26. The teacher said “ You must prepare your lessons before going to class”.

    A. The teacher said that you must prepare your lessons before going to class.

    B. The teacher said that we must prepare your lessons before going to class.

    C. The teacher said that we had to prepare our lessons before going to class.

    D. The teacher said that we had to  preparing our lessons before going to class.

    27. He bought this book last week.

    A. This book was bought by him last week.

    B. Last week, this book was bought by him.

    C. This book is bought by him last week.

    D. This book was bought by he last week.

    Choose the sentence that best combines each given pair of sentences.

    28. I was very tired. I went to bed early.

    A. I was very tired but I went to bed early.

    B. Although I was very tired but I went to bed early.

    C. I went to bed early when I was very tired

    D. I went to bed early because I was very tired.

   29. He was sitting on a chair. It was uncomfortable.

    A. The chair who he was sitting on was uncomfortable.

    B. The chair which he was sit on was uncomfortable.

    C. The chair which he was sitting on was uncomfortable.

    D. The chair whom he was sitting on was uncomfortable.

30. They heard about his bad marks. They were sad.

   A. They are sad that they heard about his bad marks.

   B. They were sad because of they heard about his bad marks.

   C. They were sad that they heard about his bad marks.

   D. They were sad so they heard about his bad marks.

   Read the following passage and choose the correct answer.

       I began teaching career nearly six years ago. I spent six years (31) _____ in a remote      village where the villagers were very poor and the living standard was low. Sometimes I was very (32)______ because of bad living condition (33)________ low pay. I was really homesick. However, at that time, with my youth enthusiasm. I tried my best to devote myself to the noblest career that was ‘teaching’. I love my poor (34)________ students (35)_______ were living in poverty. Despite the poor life, they couldn’t suffer from empty mind.

31. A. taught

B.  teaching

C. teaches

D. to teach

32.A disappointed

B. disappoints

C. disappointing

D. disappoint

33. A. so

B. because

C. and

D. although

34. A. few

B. less

C. some

D. little

35. A. who

B. which

C. whom

D. where

Read the passage and choose the best answer for each question.

Truong Yen Festival is from the 9th to the 11th day of the third lunar month, the main festival day is on the 10th day of the third lunar month. This festival is celebrated in Truong Yen Commune, Hoa Lu District, Ninh Binh Province and by the locals. The festival is in memory of the Kings of the Dinh and Le dynasties. The festival lasts for three days with many traditional games and martial arts. There are many cultural and sports activities, including a procession to carry water from the Hoang Long River to the King Dinh and King Le temples, a drum festival, and volleyball, human chess, and folk games... The most special about the Truong Yen Festival is a game called " maneuver game with red flag", which replays the childhood of Dinh Bo Linh as a buffalo boy in Truong Yên.

 36. What is the best title of the passage?

A. The Kings Festival

C. Activities of a Festival   

B. The Festival in Ninh Binh Province

D. Truong Yen Commune

 37. How long does Truong Yen Festival last?

A. Three days        

C. On the 10th day 

B. From the 9th to the 11th day.

D. During the third lunar month.

38. What is the most special about the Truong Yen Festival?

A. Many traditional games and martial arts.

B. Many cultural and sports activities.

C.  The game replays the childhood of the King Dinh.

D.  In memory of the Kings of the Dinh and Le dynasties.

39. What does the word “which” in the passage mean?

A. Martial arts         B. Cultural activities           C. Sports activities        D. A game

40. Which of the following is not TRUE?

A. The festival is in honor of the Kings of the Dinh and Le dynasties.

B. The third day of the tenth lunar month is the main festival day.

C. There are many traditional games and martial arts.

       D. Dinh Bo Linh was a buffalo boy in Truong  Yen      

2
4 tháng 3 2022

Có gì đó sai sai thì phải, Anh -> Hoá:)

4 tháng 3 2022

  5. You can speak English fluently, __________?

A. could you

B. can’t you

C. can you

D. couldn’t you

  6. On average, _________Moon is 384.400 km from ___________ Earth.

A. the-the

B. x-the

C. a-an

D. a-the

  7. _________ my opinion, he is the best football player in our team.

A. On

B. At

C. In

D. From

  8. On March 8th , women often _____ beautiful roses, postcards, lots of gifts with the best   wishes from their relatives and friends.

A. give

B. send

C. have

D. receive

  9. The driver stopped ______ a coffee because he felt sleepy.

A. have

B. to have

C. having

D. had

  10. I wish I ______ play football well.

A. can

B. could

C. am

D. did

  11. If I ________ you, I would join this English Speaking Contest.

A. were

B. am

C. would be

D. will be

  12. _______ there is a lot of noise in the city, I living there.

A. Because

B. Despite

C. In spite of

D. Although

  13. I suggest ________ a shotcut through the field . It will take much less time.

A. take

B. taking

C. to take

D. takes

  14. She has a lot of ___________ while she’s studying English.

A. difficult

B. difficulties

C. difficile

D. diffident

   15. He finds the way to a place easily. He was a very good sense of ___________

A. direction

B. humor

C. style

D. responsibility

16. There are lots of people who _____ work in remote and mountainous areas  nowadays.

A. volunteers

B. voluntary

C. voluntarily

D. volunteer

   17. If you want to _____ the other students in your class, you’ll have to work very hard.

A. catch up with

B. learn on

C. catch up

D. hurry up

 

28 tháng 2 2022

haha khó quá mik chịu 

28 tháng 2 2022

có bị đâu mà biết

haha

mình chịu

27 tháng 2 2022

a, \(Na_2O_2+2KO_2+2CO_2\rightarrow O_2\uparrow+K_2CO_3+Na_2CO_3\)

b, Tỉ lệ 2:1

1 tháng 3 2022

\(n_{H_2}=\dfrac{V}{2}+0,28V=0,195\\ =>V=250\left(ml\right)\\ m=3,78+0,195.96=22,5\left(g\right)\)

1 tháng 3 2022

m_{tăng} = 11,08 - 2,44 = 96x 

=> x = 0,09 (mol)

V = 2,016(l)

1 tháng 3 2022

$m_{tăng}$

10 tháng 3 2022

`MgCO_3+2HCl->MgCl_2+CO_2+H_2O`

`Mg+2HCl->MgCl_2+H_2`

`FeCO_3+2HCl->FeCl_2+CO_2+H_2O`

Đặt \(\hept{\begin{cases}x\left(mol\right)=n_{H_2}\\y\left(mol\right)=n_{CO_2}\end{cases}}\)

\(\rightarrow2x+44y=4,8\left(1\right)\)

Có \(\overline{M}_B=8.M_{H_2}=16\)

\(\rightarrow n_B=x+y=0,2mol\) và \(y=0,1mol\)

Theo phương trình \(n_{H_2O}=n_{CO_2}=0,1mol\)

BT H \(\text{∑}n_{HCl}=2n_{H_2O}+2n_{H_2}=0,6mol\)

BT khối lượng \(m_A+m_{HCl}=m_{\text{muối}}+m_{CO_2}+m_{H_2O}+m_{H_2}\)

\(\rightarrow m+0,6.36,5=4,8+0,1.18+40,9\)

\(\rightarrow m=25,6g\)

1 tháng 3 2022

\(n_{H_2}=n_O=0,25\left(mol\right)\\\dfrac{a}{2}=11,15-0,25.16\\ =>a=14,3\left(g\right)\)