đề thi olympic hoá học mĩ năm 2005

Ngày tải lên: 12/10/2015, 22:01

Ngày tải lên: 16/08/2013, 21:28

... oxi khối lượng a/ Hãy xác định công thức cấu tạo gọi tên A? b/ B đồng đẳng A có hoạt tính quang học Viết công thức cấu tạo gọi tên B? (Cho: Cu = 64; Fe = 56; N = 14; O = 16; H =1; Na = 23; Cl...

Ngày tải lên: 16/08/2013, 21:28

... anniversary of this international competition Not less than 125 theoretical and 50 practical problems were set in the ICHO in the mentioned twenty years In the elaboration of this collection ... his interest The International Chemistry Olympiad fulfils all preconditions to play this role excellently This review of the competition problems from the first twenty International Chemistry ... 4.2 Concerning the molar masses of alkali metals, only lithium can come into consideration, i.e the alloy consists of rubidium and lithium n(Rb) + n(Li) = 0.2 mol m(Rb) + m(Li) = 4.6 g n(Rb)...

Ngày tải lên: 06/04/2014, 15:41

... Electric current flows for hours, 56 minutes and seconds through the electrolyte Hydrogen obtained in this way was used for a synthesis with another substance, thus forming a gaseous substance A which ... have in their molecules oxygen and they can be mixed together in arbitrary ratios Oxidation of this mixture on cooling yields the only substance C that combines with NaHSO3 The ratio of the molar ... produce two ionic compounds These compounds were allowed to react with 270 mg of water but only one third of water reacted A basic solution was formed in which the content of hydroxides was 30 % by...

Ngày tải lên: 06/04/2014, 15:41

... 200 KETONES CARBOHYDRATES HYDROCARBONS Anthracene MERCAPTANS – THIOPHENOLS n-Amylmercaptan - 126 p-Thiocresol Thiophenol - 169 p-Bromothiophenol 74 - p-Cresol 36 200 o-Nitrophenol 45 - α-Naphthol ... (in mass %) a maximum value? A) potassium nitrate, B) barium nitrate, C) aluminium nitrate, D) lithium nitrate, E) sodium nitrate 10 To which carbon atom (indicate the serial number) will chlorine ... 1979 PROBLEM An alloy comprises the following metals: cadmium, tin, bismuth, and lead A sample of this alloy weighing 1.2860 g, was treated with a solution of concentrated nitric acid The individual...

Ngày tải lên: 06/04/2014, 15:41

... of pH = 8.8 The -2 anion A of this acid is coloured and has a molar decadic absorption coefficient ε of - 2.1 × 10 cm mol A layer l of the solution with 1.0 cm thickness absorbs 60 percent of ... N-CH2-CH2-N HOOC-CH2 CH2-COOH 4- 2- The anion of this acid, C10H12N2O8 , forms a stable complex CaC10H12N2O8 with calcium ions The stability constant of this complex ion is given by: K= 2[ CaC10H12N2O8 ... 4.3 Calculate the rate constant for this reaction at the four temperatures given in the table 4.4 Calculate the average value of the activation energy for this reaction You should take the average...

Ngày tải lên: 06/04/2014, 15:42

... success of this important international competition I am sure about the usefulness of the this review of the ICHO problems It may serve not only as archive material but, in particular, this review ... International Information Centre in Bratislava (Slovakia) to the development of this world known international competition This Volume contains 154 theoretical and 46 practical competition problems ... 39th ICHO 1038 1095 34 ICHO th 40 ICHO Quantities and their units used in this publication 1137 Preface This publication contains the competition problems (Volume 2) from the 21st – 40th...

Ngày tải lên: 06/04/2014, 15:42

... solution which contains hexachloroplatinate(IV) ions with sodium carbonate In this process PtO2 n H2O is formed and this is in turn converted to platinum(IV) oxide upon subsequent filtering and ... an adiabatic expansion than in an isothermal expansion Is this because the adiabatic expansion is characterized by (check the square you think is most important) The expansion is always irreversible ... immediately with thiosulphate solution Reagents and Apparatus Unknown sample, 0.2000 M Hanus solution, dichloro-methane, 15 % KI solution in distilled water, distilled water, 0.2000 M sodium thiosulphate,...

Ngày tải lên: 06/04/2014, 15:42

... the low spin configuration that may exist for this complex: The correct answer is high spin configuration The best evidence to support your answer for this high/low spin selection is magnetic moment ... the reaction flask Shake well Titrate the remaining iodine with standard thiosulphate solution Record the volume of the thiosulphate solution 10 Repeat the above steps (Steps to 9) for Flask II, ... in Fe ion in the complex? Write the high spin and the low spin configurations that may exist for this complex Which configuration, high or low spin, is the correct one? What is the best evidence...

Ngày tải lên: 06/04/2014, 15:43

... Germany Since the C concrete walls and the roof of the house are relatively thin (20.0 cm) there will be a loss of energy This energy is released to the surroundings (heat loss released to water ... disproportionation into Ca and CaCl2 the standard enthalpy of this process has to be calculated (The change of the entropy ∆S is very small in this case, so its influence is negligible.) 3.6 Does the ... products with an endo-stereochemistry The preference of this configuration was outlined in problem 6.2, structure C As shown in structure C this endo- configuration is characterized by the two H...

Ngày tải lên: 06/04/2014, 15:44

... ≈ 66,7% 240 Vậy, % CuO = 33,3% % Fe2O3 = 66,7% ⇒ % CuO = 3) Nếu kí hiệu kim loại M, hoá trị n, gốc axit R hoá trị m Hãy viết công thức tổng quát axit, bazơ, muối Giải: CTHH tổng quát axit là: ... 11,2l khí A Biết không khí có chứa 20% khí oxi khí đo ĐKTC Giải: Gọi CTHH tổng quát khí A CxHy Theo đề bài: d A / H = ⇒ MA = 2.8 = 16 (g) Có: %C = 75% → %H = 100% - 75% = 25% ⇒ mC 75 12 x 75 x 75 ... ……………………… 1886mol CO2 mCO = 1866.44 = 82104 g ≈ 82kg ⇒ 2) Hỗn hợp X gồm Fe kim loại A, B (cùng hoá trị II) với tỉ lệ n Fe:nA:nB = 1:2:3 Cho m gam hỗn hợp X tác dụng hết với HCl thu 13,44l khí...

Ngày tải lên: 09/07/2014, 17:00

... kiểu hình học đường thẳng, chúng triệt tiêu lẫn XeF4 cực Tất liên kết Xe-F phân cực nhau, kiểu hình học vuông phẳng, chúng triệt tiêu lẫn XeO3 có cực Liên kết Xe-F phân cực nhau, kiểu hình học không ... cacbon dioxit đến dư vào dung dịch canxi hidroxit f Etanol đun nóng nhẹ với kali dicromat axit hoá Bài Phản ứng clorofom clo có chế đưa sau: Bước 1: Cl2 (k) 2Cl (k) nhanh Bước 2: CHCl3 (k) + ... Xenon tạo nhiều hợp chất như: XeF2, XeF4 XeO3 a Vẽ cấu trúc Liuyt cho phân tử b Mô tả dạng hình học hợp chất bao gồm góc liên kết c Cho biết giải thích phân tử có cực hay cực d Tính toán việc...

Ngày tải lên: 09/08/2014, 14:20