Cho giá trị thế điện cực chuẩn của một số cặp oxi hoá - khử:
\(E_{F e^{2+} / F e}^{0}=-0,44 \mathrm{V} ; E_{Z n^{2+} / Z n}^{0}=-0,76 \mathrm{V} ; E_{C u^{2+} / C u}^{0}=0,34 \mathrm{V} ; E_{A g^{+} / A g}^{0}=0,8 \mathrm{V}\). Hãy cho biết ion nào có thể oxi hoá được kim loại Fe.
\(\mathrm{Zn}^{2+}\) và \(\mathrm{Ag}^{+}\).
\(\mathrm{Cu}^{2+}\) và \(\mathrm{Zn}^{2+}\).
\(\mathrm{Cu}^{+}\)và \(\mathrm{Ag}^{+}\).
\(\mathrm{Cu}^{2+}\) và \(\mathrm{Ag}^{+}\).
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Chất khử của cặp oxi hoá - khử có thế điện cực nhỏ hơn tác dụng với chất oxi hoá của cặp oxi hoá khử có thế điện cực lớn hơn, tạo ra dạng oxi hoá và dạng khử tương ứng mà:
\(E_{\mathrm{Fe}^{2+} / \mathrm{Fe}}^{0}=-0,44 \mathrm{V}<E_{\mathrm{Cu}^{2+} / \mathrm{Cu}}^{0}=0,34 \mathrm{V}\) nên ion \(\mathrm{Cu}^{2+}\) oxi hóa được kim loại Fe theo phản ứng: \(\mathrm{Fe}+\) \(\mathrm{Cu}^{2+} \rightarrow \mathrm{Fe}^{2+}+\mathrm{Cu}\) (thỏa mãn quy tắc \(\alpha\) ). \(E_{\mathrm{Fe}^{2+} / \mathrm{Fe}}^{0}=-0,44 \mathrm{V}<E_{\mathrm{Ag}^{+} / \mathrm{Ag}}^{0}=0,8 \mathrm{V}\) nên ion \(\mathrm{Ag}^{+}\)oxi hóa được kim loại Fe theo phản ứng: \(\mathrm{Fe}+2 \mathrm{Ag}^{+} \rightarrow \mathrm{Fe}^{2+}+2 \mathrm{Ag}\) (thỏa mãn quy tắc \(\alpha\) ).
Câu hỏi liên quan
Một vật khối lượng 10 kg được kéo đều trên sàn nằm ngang bằng một lực 20 N hợp với phương ngang một góc 300. Khi vật di chuyển 2 m trên sàn thì lực thực hiện một công
Cho ba tập hợp sau:
A = {m + 1; 2}
B = {1; n – 3}
C = {t; 2}
Hỏi m, n, t nhận giá trị nào sau đây thì A = B = C?
Ngành công nghiệp hiện đại của Hoa Kì không phải là ngành gì?
Read a flyer promoting a new gym. Decide if the statements are true (T) or false (F).
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Giải phương trình lượng giác sau: \(\cot x = \cot 2x\)?
Cho \(f\left( x \right) = a{x^2} + bx + c\), \(\left( {a \ne 0} \right)\) và \(\Delta = {b^2} - 4ac\). Cho biết dấu của \(\Delta \) khi \(f\left( x \right)\) luôn cùng dấu với hệ số \(a\) với mọi \(x \in \mathbb{R}\)?
Ở thực vật sống trên cạn, nước và ion khoáng được hấp thụ chủ yếu bởi cơ quan nào?
Ý kiến nào sau đây là không đúng khi bàn về vấn đề lạm phát?
Mark the letter A, B, C or D on your answer sheet to indicate the best arrangement of utterances or sentences to make a meaningful exchange or text in each of the following questions from 13 to 17.
a. However, once the foundation is laid, the real work begins as they start building more complex systems of thought and understanding.
b. Learning a new language is challenging, especially at the beginning when students are overwhelmed by grammar rules and unfamiliar vocabulary.
c. With continuous practice, learners gradually develop confidence in their speaking, listening, and writing skills, although progress may seem slow at first.
d. Many language learners experience frustration early on, but it's important to remember that fluency comes with time and dedication.
e. The sense of accomplishment that comes from mastering a language makes the effort worthwhile, opening doors to new cultures and opportunities.
Read the following advertisement and mark the letter A, B, C, or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 1 to 6.
HASTAG ACTIVISM - WORTH CLICKING ON?
Platforms like Facebook and Twitter are being used more and more to ___(1)___ awareness of social issues and ___(2)___ for good causes. There have been several examples of ___(3)___ campaigns in recent years. For instance, the #IceBucketChallenge proved a viral success in raising awareness and funds ___(4)___ ALS, a disease that ___(5)___. Not only did people all over the world post videos of themselves tipping a bucket of iced water over their heads, ___(6)___ they also nominated other people to do the challenge, as well as donating to the Association.
(Adapted from Friends Global)
Đường thẳng y = m không cắt đồ thị hàm số khi?
Những công nghệ nào sau đây thuộc về công nghệ xử lý chất thải trong chăn nuôi
Read the following passage about managing change and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40.
Growing up in Athens, Greece, Lydia Borsi remembers feeling tested when she tried to deal with mental health issues. Borsi says she had been seeing a therapist for anxiety. But she notes that people in Greece do not openly discuss mental health issues, which also get little attention in general healthcare services. “It was a lot more secretive. And people thought that I was a lot more unique,” Borsi said.
That all changed in 2017 when she moved to the United States to study at the University of Rochester in Rochester, New York. “When I came here, I really liked that people were not afraid to speak up about mental health and say that it’s important,” she said. The university was very supportive of her needs and offered plenty of information. She also became involved with a school group called Active Minds that helps students deal with mental health issues. [A]
Then due to the spread of the novel coronavirus, the University of Rochester had to move all its classes and some of its mental health resources online. Luckily, Borsi was able to connect with a mental health expert outside the school, in the local community. [B]
But as many of her American friends returned home, Borsi was stuck. Greece had succeeded in limiting the spread of the virus within its borders, but flights there from the U.S. are barred until July. Also, the health crisis has put her plans to seek admission to medical school in Britain on hold. [C] And she is not alone.
[D] In April, Active Minds launched a survey of over 2,000 students at U.S. colleges and universities. The study found that over 80 percent of those asked said the coronavirus crisis had negatively affected their mental health. One in five said it has affected them severely.
Laura Horne, chief program officer at Active Minds, says the findings are especially troubling given that the crisis is only going to make it harder for colleges and universities to help these students. “Colleges and universities had to pivot rather quickly to respond to COVID-19 and figure out all facets of university life, including mental health services. Now they have to figure out how to communicate with students,” Horne said.
Frank Chen is a Houston, Texas-based psychiatrist who has worked with college-age young adults. He points out that individuals at that age are in an important stage of their mental development. And college can be a difficult experience for students with or without mental health issues, as they balance work, studies, and personal relationships. Adding a major world event, like the spread of the coronavirus, makes it very difficult to predict what the long-term psychological effects might be. “I don’t think that there’s another event in the history of the people who are alive now that can really measure up to this,” said Chen.
Which of the following is NOT mentioned by Frank Chen as a factor affecting college students’ mental health?
Đổi đơn vị dung lượng sau: 1B = ? Bit
Speech is one of the most important ways of communicating. It consists of far more than just making noises. To talk and also (627) ___________ by other people, we have to speak a language, that is, we have to use combinations of sounds that everyone agrees to stand for a particular object or idea. Communication would be impossible (628) _________________. Learning a language properly is very important. The basic vocabulary of English is not very large, and not only about 2,000 words are needed to speak it quite well. But (629) ________________, the more precise you can be about their exact meaning. Words are the main thing we use in communicating what we want to say. (630) ________________. (631) _______________ of voice can express many emotions and show whether we are pleased or angry, for instance.
Câu 627:
To talk and also (627) ___________ by other people, we have to speak a language, that is, we have to use combinations of sounds that everyone agrees to stand for a particular object or idea.
Read the following advertisement and mark the letter A, B, C or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 1 to 6.
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• Don’t miss out on this (5)_______-in-a-lifetime opportunity to upgrade your tech.
• Start (6)_________the benefits of advanced technology today, or wait for the future to catch up!
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Cho mệnh đề A “∀x ∈ ℝ, x2 – 2x + 15 < 0”. Mệnh đề phủ định của mệnh đề A là:
Biểu thức lôgic nào dưới đây thể hiện số a thuộc nửa khoảng (5, 7]?
Tập hợp P={x∈R−1<2x+1≤11} được viết lại dưới dạng đoạn, khoảng, nửa khoảng là
Giả sử chiều cao (tính bằng cm) của một giống cây trồng (trong vòng 1 số tháng nhất định) tuân theo quy luật logistic được mô hình hóa bằng hàm số: \(f(t)=\frac{200}{1+4 e^{-t}}, t \geq 0\). Trong đó , thời gian \(t\) được tính bằng tháng kể từ khi hạt bắt đầu nảy mầm. Khi đó đạo hàm \(f^{\prime}(t)\) sẽ biểu thị tốc độ tăng chiều cao của giống cây đó. Hỏi sau khi hạt giống bắt đầu nảy mầm thì sau bao nhiêu tháng tốc độ tăng chiều cao của cây là lớn nhất? Kết quả lấy phần nguyên.
