chỉ dùng thêm nước hãy nhận biết 4 chất rắn sau đây: K2O, CaO, Fe2O3, Na chứa trong các lọ riêng biệt. Viết các phương trình phản ứng
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18 tháng 3
a, Bạn tự tóm tắt nhé.
b, \(n_{C_2H_5OH}=\dfrac{0,46}{46}=0,01\left(mol\right)\)
\(n_{CH_3COOH}=\dfrac{6}{60}=0,1\left(mol\right)\)
PT: \(C_2H_5OH+CH_3COOH⇌CH_3COOC_2H_5+H_2O\) (đk: to, H2SO4 đặc)
Xét tỉ lệ: \(\dfrac{0,01}{1}< \dfrac{0,1}{1}\), ta được CH3COOH dư.
Theo PT: \(n_{CH_3COOC_2H_5}=n_{C_2H_5OH\left(pư\right)}=n_{CH_3COOH}=0,01\left(mol\right)\)
⇒ mCH3COOC2H5 = 0,01.88 = 0,88 (g)
nC2H5OH (dư) = 0,1 - 0,01 = 0,09 (mol)
⇒ mC2H5OH (dư) = 0,09.46 = 4,14 (g)
D
18 tháng 3
1) I like living in a city because there are many opportunities for education, jobs, and entertainment. The city has modern facilities, good public transportation, and many interesting places to visit. It is also easy to meet new people and experience different cultures.
2) In my city, there are a lot of famous places, such as: Back Beach, Statue of Christ the King, Cloud Lake, ...
3) A common and easy part-time job for students is working as a cashier in a supermarket. It doesn’t require much experience, and students can work flexible hours. Other good options include tutoring, working in coffee shops, or doing freelance work online.
4) People change jobs often for many reasons. Some want a higher salary, while others look for a better work environment. Sometimes, people feel bored with their current job and want a new challenge. Career growth and job satisfaction are also important factors.
5) "I would never want to be a literature teacher because I think literature is boring, no absolute correct answer, feels long-winded and confusing,... That's my opinion
SV
Sinh Viên NEU
CTVVIP
20 tháng 3
1 If the city don't fix the traffic lights, there might be more accidents
2 The team was discussing about the repair plan when the manager walked in last night
D
18 tháng 3
Answer:
1) There were so many customers that we had to work overtime.
2) If more bike lanes aren't added, people won’t feel safe cycling.
3) I expect to get feedback on my job application.
SV
Sinh Viên NEU
CTVVIP
20 tháng 3
1 There were so many customers that we had to work overtime
2 If more bike lanes are not added, people won't feel safe cycling
3 I expect to get feedback on my job application
- Trích mẫu thử.
- Hòa tan từng mẫu thử vào nước.
+ Tan: K2O, CaO (1)
PT: \(K_2O+H_2O\rightarrow2KOH\)
\(CaO+H_2O\rightarrow Ca\left(OH\right)_2\)
+ Tan, có sủi bọt khí: Na
PT: \(2Na+2H_2O\rightarrow2NaOH+H_2\)
+ Không tan: Fe2O3
- Dẫn khí CO2 vào 2 dung dịch vừa thu được từ nhóm (1)
+ Dung dịch vẩn đục: CaO
PT: \(Ca\left(OH\right)_2+CO_2\rightarrow CaCO_3+H_2O\)
+ Không hiện tượng: K2O.
- Dán nhãn.