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A, C3H7COOH + C2H5OH → C3H2CÔC2H5 + H2O

B, 1,88

27 tháng 4
a. Viết phương trình phản ứng Phản ứng giữa butyric acid ( 𝐶𝐻3 [ 𝐶𝐻2 ]2𝐶𝑂𝑂𝐻) và ethanol ( C2H5OH𝐶2𝐻5𝑂𝐻) có sự xúc tác của  H2SO4𝐻2𝑆𝑂4 đặc và đun nóng:
CH3[CH2]2COOH+C2H5OHCH3[CH2]2COOC2H5+H2O𝐶𝐻3[𝐶𝐻2]2𝐶𝑂𝑂𝐻+𝐶2𝐻5𝑂𝐻𝐻2𝑆𝑂4đc,𝑡∘𝐶𝐻3[𝐶𝐻2]2𝐶𝑂𝑂𝐶2𝐻5+𝐻2𝑂(Sản phẩm thu được là ethyl butyrate)
b. Tính giá trị của  m𝑚 Để tính khối lượng ester, chúng ta thực hiện các bước sau: 1. Tính số mol các chất tham gia:
  • Phân tử khối butyric acid ( C4H8O2𝐶4𝐻8𝑂2):  𝑀 =88 g/mol
    ⇒𝑛butyricacid =1,7688 =0 , 02 mol
  • Phân tử khối ethanol ( C2H6O𝐶2𝐻6𝑂):  𝑀 =46 g/mol
    ⇒𝑛ethanol =1,2846 ≈0 , 0278 mol
2. Xác định chất hết - chất dư:
Theo phương trình, tỉ lệ mol là 1:1. Ta thấy  0 , 02 <0 , 0278, do đó butyric acid hết, ethanol dư. Tính toán lượng ester theo butyric acid.
⇒𝑛ester(lýthuyt) =𝑛butyricacid =0 , 02 mol
3. Tính khối lượng ester thực tế ( m𝑚):
  • Phân tử khối ethyl butyrate ( 𝐶6𝐻12 𝑂2):  𝑀 =116 g/mol
  • Hiệu suất phản ứng ( H𝐻) = 81%
    m=nester (lý thuyt)×Mester×H100𝑚=𝑛ester(lýthuyt)×𝑀ester×𝐻100
27 tháng 4
a. Viết phương trình phản ứng Phản ứng điều chế ethyl butyrate (ethyl butanoate) từ butyric acid (butanoic acid) và ethanol là phản ứng ester hóa, có axit  H2SO4𝐻2𝑆𝑂4 đặc làm xúc tác và đun nóng:
C3H7COOH+C2H5OHH2SO4đcC3H7COOC2H5+H2O𝐶3𝐻7𝐶𝑂𝑂𝐻+𝐶2𝐻5𝑂𝐻𝐻2𝑆𝑂4đc𝑡∘𝐶3𝐻7𝐶𝑂𝑂𝐶2𝐻5+𝐻2𝑂(Butyric acid + Ethanol   Ethyl butyrate + Nước)
b. Tính giá trị của m 1. Tính số mol các chất tham gia:
  • Phân tử khối của butyric acid ( C3H7COOH𝐶3𝐻7𝐶𝑂𝑂𝐻):  𝑀 =88 g/mol.
    nbutyric acid=1,7688=0,02mol𝑛butyricacid=1,7688=0,02mol
  • Phân tử khối của ethanol ( C2H5OH𝐶2𝐻5𝑂𝐻):  𝑀 =46 g/mol.
    nethanol=1,2846≈0,0278mol𝑛ethanol=1,2846≈0,0278mol
2. Xác định chất hết - chất dư:
Theo phương trình, tỉ lệ mol là  1 1. Ta thấy  0 , 02 <0 , 0278, do đó ethanol dư và tính toán lượng ester theo butyric acid (chất thiếu).
3. Tính khối lượng ester (m) theo lý thuyết:
  • Theo phương trình:  𝑛esterlýthuyt =𝑛butyricacid =0 , 02 mol.
  • Phân tử khối của ethyl butyrate ( C3H7COOC2H5𝐶3𝐻7𝐶𝑂𝑂𝐶2𝐻5):  𝑀 =116 g/mol.
    mlý thuyt=0,02×116=2,32gam𝑚lýthuyt=0,02×116=2,32gam
4. Tính khối lượng ester thực tế thu được (với hiệu suất 81%):
m=mlý thuyt×H100=2,32×81100=1,8792gam𝑚=𝑚lýthuyt×𝐻100=2,32×81100=1,8792gam
Đáp số:
  • a. Phương trình:  C3H7COOH+C2H5OH⇌C3H7COOC2H5+H2O𝐶3𝐻7𝐶𝑂𝑂𝐻+𝐶2𝐻5𝑂𝐻⇌𝐶3𝐻7𝐶𝑂𝑂𝐶2𝐻5+𝐻2𝑂
  • b.  𝑚 =1 , 8792 gam.

a) CH3CH2CH2COOH + C2H5OH ⇌ CH3CH2CH2COOC2H5 + H2O (H2SO4 đặc, t°) b) n(axit) = 1,76 / 88 = 0,02 mol n(ancol) = 1,28 / 46 ≈ 0,0278 mol → axit hết (chất giới hạn) n(este) lt = 0,02 mol m(este) lt = 0,02 × 116 = 2,32 g m(thực tế) = 2,32 × 81% = 1,8792 g ≈ 1,88 g

27 tháng 4

a,C3H7COOH+C2H5OH---------C3H7COOC2H5+H2

b,m=mlythuyet×H÷100=2,32×81÷100=1,8792gam

27 tháng 4
a. Viết phương trình phản ứng Phản ứng ester hóa giữa butyric acid và ethanol với xúc tác  H2SO4𝐻2𝑆𝑂4 đặc, đun nóng: C3H7COOH+C2H5OHC3H7COOC2H5+H2O𝐶3𝐻7𝐶𝑂𝑂𝐻+𝐶2𝐻5𝑂𝐻𝐻2𝑆𝑂4đc,𝑡𝑜𝐶3𝐻7𝐶𝑂𝑂𝐶2𝐻5+𝐻2𝑂 b. Tính giá trị của  m𝑚 1. Tính số mol các chất tham gia:
  • 𝑀𝐶3𝐻7𝐶𝑂𝑂𝐻 =88 g/mol ⇒𝑛acid =1,7688 =0 , 02 mol
  • 𝑀𝐶2𝐻5𝑂𝐻 =46 g/mol ⇒𝑛alcohol =1,2846 ≈0 , 0278 mol
2. Xác định chất giới hạn:
So sánh tỉ lệ mol:  0 , 02 <0 , 0278. Do đó, hiệu suất phản ứng tính theo butyric acid.
3. Tính khối lượng ester ( m𝑚):
  • Theo phương trình:  𝑛esterlýthuyt =𝑛acid =0 , 02 mol
  • Khối lượng ester theo lý thuyết:  0 , 02 ×116 =2 , 32 gam (với  𝑀ethylbutyrate =116)
  • Khối lượng ester thực tế với hiệu suất  81 %:
    m=2,32×81100=1,8792gam𝑚=2,32×81100=1,8792gam
Kết luận: Giá trị của  m𝑚 là 1,8792 gam.
10 giờ trước (12:30)
𝐶𝐻3[𝐶𝐻2]2𝐶𝑂𝑂𝐻+𝐶2𝐻5𝑂𝐻𝐻2𝑆𝑂4đc,𝑡∘𝐶𝐻3[𝐶𝐻2]2𝐶𝑂𝑂𝐶2𝐻5+𝐻2𝑂 nacid=1,7688=0,02mol nalcohol=1,2846≈0,0278mol
  • Phân tử khối của ethyl butyrate ( C3H7COOC2H5𝐶3𝐻7𝐶𝑂𝑂𝐶2𝐻5):  𝑀ester =116 g/mol
  • Hiệu suất phản ứng ( H𝐻) =  81 %
    m=nester×Mester×H100=0,02×116×81100=1,8792gam𝑚=𝑛ester×𝑀ester×𝐻100=0,02×116×81100=1,8
Choose the best answer in each sentence below by circling it. 1. You are late. If you …… a few minutes earlier, you …… him.       A. came / would meet        B. had come / would have met          C. come / will meet            D. had come / would meet2. “Can I borrow your car for this evening?”“Sure, but Nora’s using it right now. If she …… it back in time, you’re welcome to borrow it.”     A. brings                B....
Đọc tiếp

Choose the best answer in each sentence below by circling it.

1. You are late. If you …… a few minutes earlier, you …… him. 

     A. came / would meet        B. had come / would have met    

     C. come / will meet            D. had come / would meet

2. “Can I borrow your car for this evening?”

“Sure, but Nora’s using it right now. If she …… it back in time, you’re welcome to borrow it.”

     A. brings                B. would bring                 C. will bring                       D. brought

3. We’re going to lose this game …… the team doesn’t start playing better soon.

A. if                             B. unless                      C. although                 D. whereas

4. If I …… somebody else, I’d like to be a film star.  

     A. could be                             B. would be           C. become       D. must be

5. If he had told me the truth, I …… him.     

     A. would have not punished                      B. would not have punished

     C. would not punish                                  D. will not punish

6. If they had not given me advice, I …… again.   

     A. would have failed                     B. would fail         C. would have been failed                        D. wouldn’t fail

7. …… immediately, I will call a policeman.

     A. Unless you leave           B. If you leave             C. If you didn’t leave                        D. Unless you left      

8. Bill …… more photographs if he …… more film.  

     A. would have taken / had had                  B. would have taken / had

     C. would take / has had                             D. would take / had had        

9. If there …… no floods last year, the crop …… better. 

     A. had been / would have been     B. were / would be  

     C. had / would have been               D. was / would have been

10. Had you told me that this was going to happen, I …… it.   

     A. would never have believed         B. don’t believe

    C. hadn’t believed                            D. can’t believe

11. If someone …… into the store, smile and say, “May I help you?”

     A. comes                B. came                       C. come                       D. could come

12. If I had a chance to do creative work, I …… happy working in an office.

     A. would be                       B. will be                     C. would have             D. will feel

13. If they …… soon, I’m not going to wait.  

     A. don’t come        B. won’t come                   C. hadn’t come        D. didn’t come

14. If I …… hungry, I …… something. But I am not hungry now.  

     A were / would eat                         B. had been / would have eaten        

     C. had been / would eat      D. were / would have eaten

15. You won’t pass the examination …… you study more.    

     A. unless         B. as           C. if                 D. whether

16. I’m playing tennis tomorrow …… it’s raining.    

     A. unless              B. if                   C. as long as    D. provided

17. Tell him to ring me if you …… him.   

     A. see                     B. saw             C. have seen                D. had seen

18. Unless she ……, she’ll be late.    

     A. hurries               B. didn’t hurry                        C. hurried                    D. doesn’t hurry

19. Would George be angry if I …… his bicycle without asking?  

     A. took      B. take             C. had taken    D. would take

20. I …… you a postcard while I was on holiday if I …… your address.

A. would have sent / had had       B. would have sent / had      

C. would send / had                      D. would send / had had

21.  …… still my friend if I were put in prison?  

     A. Would you be            B. Will you be           C. Would you        D. Would you are

22.  If anybody …… any question, please ask me after class.  

     A. has         B. have                C. don’t have                      D. doesn’t have

23.  If I weren’t working for an accounting firm, I …… in a bank.

A. would be working        B. will work         C. have worked         D. work

24. He said, “…… watch TV all the evening if you wish.”  

     A. You may           B. You have to              C. You need to             D. You should

25. If he ……, please tell me.    

     A. comes                B. won’t come                        C. will come                D. come

2
14 tháng 8 2021

Theo em nghĩ thì là C vì You thì ko thể dùng had đc.

14 tháng 8 2021

sao nhiều thế. Ai mà trả lời nổi

Read the passage below and choose the best answer (A, B, C or D) to each question.The nuclear family, consisting of a mother, father, and their children f may be more an American ideal than an American reality. Of course, the so-called traditional American family was always more varied than we had been led to believe, reflecting the very different racial, ethnic, class, and religious customs among different American groups.The most recent government statistics reveal that only about one third...
Đọc tiếp

Read the passage below and choose the best answer (A, B, C or D) to each question.

The nuclear family, consisting of a mother, father, and their children f may be more an American ideal than an American reality. Of course, the so-called traditional American family was always more varied than we had been led to believe, reflecting the very different racial, ethnic, class, and religious customs among different American groups.

The most recent government statistics reveal that only about one third of all current American families fit the traditional mold and another third consists of married couples who either have no children or have none still living at home. Of the final one third, about 20 percent of the total number of American households are single people, usually women over sixty-five years of age. A small percentage, about 3 percent of the total, consists of unmarried people who choose to live together; and the rest, about 7 percent, are single, usually divorced parents, with at least one child.

1.   With what topic is the passage mainly concerned?

A. The traditional American family.

B.  The nuclear family.

C.  The ideal family.

D. The current American family

2.   The author implies that...................

A. there has always been a wide variety of family arrangements in the United States

B. racial, ethnic, and religious groups have preserved the traditional family structure

C. the ideal American family is the best structure  

D. fewer married couples are having children

3.  Who generally constitutes a one-person household?

A. A single in his twenties.

B. A single woman in her late sixties.

C. An elderly man.

D. A divorced woman,

4.  According to the passage, married couples whose children have grown or who have no children represent...................

A. 7 percent of households

B. 20 percent of households

C. 33, 3 percent of households

D. 3 percent of households

5.  The word "current" in line 7 is closest in meaning to...................

A. present                                     B. contemporary

C. now                                          D. modern

4
2 tháng 10 2021

1.A

2.D

3.B

4.D

5.A

2 tháng 10 2021

Hello

6 tháng 5 2019

1+1=2

ko hiểu

ko bt

ko xem

6 tháng 5 2019

1+1=2

cái này bậy quá ko nên nói=))

con nào ko biết

cái này còn ko biết hơn nữa

1 tháng 8 2021

Đề bài là: Viết lại những câu này bằng mệnh đề tương đối với giới từ

28 tháng 1 2022

1: D. sector

2: A. effective

3: B. wilderness

28 tháng 1 2022

1  A. form     B. shortcoming     C. chore     D. sector

2 A. effective     B. eradicate     C. enthusias     D. effort

3 A.rhinoceros     B. wilderness     C. digestion     D. diversity

HT

28 tháng 1 2022

B. campus

28 tháng 1 2022

campus

Yesterday, we (arrange) (meet) the scientist here.                        I hate (practise) (read) aloud without (learn) the new words. practise                     My friend (give) up (smoke) since he got married. _________________My form teacher (ofen, not, allow) us (smoke) in the laboratory. 1.                        John always (avoid) (speak) to the teacher about it. _________________2.                        Davis...
Đọc tiếp

Yesterday, we (arrange) (meet) the scientist here. 

                       I hate (practise) (read) aloud without (learn) the new words. practise

                     My friend (give) up (smoke) since he got married. _________________

My form teacher (ofen, not, allow) us (smoke) in the laboratory. 

1.                        John always (avoid) (speak) to the teacher about it. _________________

2.                        Davis (not finish) (write) the report before 9 last night. ______________

3.                        Most people (preper) (spend) money to (earn) it. ___________________

4.                        The children just (stop) (play) football because it is too dark. _________________________

5.                        Since the teacher (begin) (teach) this lesson, he hasn’t smiled. ________________________

6.                        I and my sister couldn’t study because of the noise, so I (have) (ask) the boys (stop) (argue). __________________________________________

7.                        Robert (give) up (play) football years ago. ________________________

8.                        Mr John (work) in the same place for 30 years and he (not, plan) (retire) now._______________________

9.                        If you want (pass) your exam, you’ll need (study) more.______________

10.                   After the girls (hear) the whole story, they (start) (laugh) joyfully. __________________________________

0
6 tháng 10 2018

Viết lại câu sao cho nghĩa không đổi

1) "You took my ipad, Peter" her mother said.

→→Peter's mother accused...........Peter of taking her ipad..................

2)" You're always forgetting your homework, Nam

→→Nam's teacher blamed.........Nam for forgetting his homework....................

3) It takes me two weeks to camplete this picture.

→→I spend two weeks campleting........this picture......................

6 tháng 10 2018

1. Him of taking her ipad

2. Him on forgetting his homework

3. This picture

1. adequate /ˈædɪkwət/ (a) :  thỏa đáng, phù hợp

2. e-learning /ˈiː lɜːnɪŋ/(n) :  hình thức học trực tuyến

3. employable /ɪmˈplɔɪəbl/ (a) :  có thể được thuê làm việc

4. facilitate /fəˈsɪlɪteɪt/ (v) :  tạo điều kiện thuận lợi