1. Hòa tan 3,56 gam oleum vào lượng nước dư thu được 100ml dung dịch X . Để trung hòa 50ml dung dịch X cần dùng 40ml dung dịch nạp 1,0M . Vậy công thức của oleum là 2 . Một dung dịch oleum có công thức H2SO4. Lấy 3.38g oleum nói trên pha thành 100ml dung dịch X . Để trung hòa 50 ml dung dịch X cần dùng vừa đủ 400 ml dung dịch NaOH 0,1M . Tính khối lượng oleum cần tỷ thiết để có thể pha loãng với nước thành 400gam dung dịch H2SO4 9,8% 3 . Cho 0,015 mol một loại hợp chất oleum vào nước thu được 200ml dung dịch X . Để trung hòa hoàn toàn 100ml dung dịch X cần dùng 400ml dung dịch nạp 0,15M . Phần trăm về khối lượng của nguyên tố lưu huỳnh trong oleum trên là

Các câu hỏi liên quan

School exams are, generally speaking, the first kind of tests we take. They find out how much knowledge we have ...1. But do they really show how intelligent we are? After all, isn’t it a ........2 that some people who are very successful academically don’t have any ........3 sense? Intelligence is the speed ........4 which we can understand and .........5 to new situations and it is usually tested by logic puzzles. Although scientists are now preparing ..........6 computer technology that will be able to “read” our brains, ........7 tests are still the most popular ways of measuring intelligence. A person’s IQ is their intelligence .......8 is measured by a special test. The most common IQ tests are ........9 by Mensa, an organization that was founded in England in 1946. By 1976 it .......10 1,300 members in Britain. Today there are 44,000 in Britain and 100,000 worldwide, ........11 in the US. People taking the tests are judged in ........12 to an average score of 100, and those who score over 148 are entitled to join Mensa. This ......13 at 2% of the population. Anyone from the age of six can take the tests. All the questions are straightforward and most people can answer them if .......14 enough time. But that’s the problem - the whole .......15 of the tests is that they’re against the clock. 1. a. fetched b. gained c. attached d. caught 2. a. case b. fact c. circumstance d. truth 3. a. natural b. bright c. sharp d. common 4. a. on b. to c. in d. at 5. a. accord b. react c. answer d. alter 6. a. advanced b. forward c. ahead d. upper 7. a. at this age b. for the present c. at the time d. now and then 8. a. how b. that c. as d. so 9. a. appointed b. commanded c. run d. steered 10. a. held b. had c. kept d. belonged 11. a. largely b. enormously c. highly d. considerably 12. a. concern b. relation c. regard d. association 13. a. adds up b. turns to c. comes up d. works out 14. a. allowed b. spared c. let d. provided 15. a. reason b. point c. matter d. questio