Question

21. (02-12-15) 60 мл 4 М-ного раствора ЭCl2 весят 83,2г. EcЛИ Известно что КОНЦентрация раствора равна 60%, определите относительную атомную массу элемента 3? A) 137 В) 56 C) 65 D) 64 E) 40 E

Answer 1

Ответ:

а) 137

Объяснение:

60 мл данного раствора содержат 0,06*4 = 0,24 моль растворённого вещества, что составляет 83,2*0,6 = 49,92 грамма. Тогда один моль растворённого вещества имеет массу 49,92:0,24 = 208 граммов, из которых на неизвестный элемент приходится 208 - 2*35,5 = 137 граммов. Следовательно, относительная атомная масса элемента составляет 137 а.е.м.

Answer 2

I searched the web for your question and found some results that might help you. Here is a summary of what I found:

- The question is about finding the relative atomic mass of element E, which forms a compound ECl2 with chlorine. The question gives the following data: the volume of the solution is 60 mL, the molarity of the solution is 4 M, the mass of the solution is 83.2 g, and the concentration of the solution is 60%. - To solve the question, we need to use the following formulas: - The molarity of a solution is the number of moles of solute per liter of solution. M = n/V - The concentration of a solution is the mass of solute per mass of solution. C = m1/m2 - The relative atomic mass of an element is the mass of one atom of that element compared to the mass of one atom of carbon-12. A = m/E - Using these formulas, we can calculate the relative atomic mass of element E as follows: - First, we find the number of moles of ECl2 in the solution using the molarity formula. n = MV = 4 * 0.06 = 0.24 mol - Next, we find the mass of ECl2 in the solution using the concentration formula. m1 = Cm2 = 0.6 * 83.2 = 49.92 g - Then, we find the mass of one mole of ECl2 using the number of moles and the mass of ECl2. m = m1/n = 49.92/0.24 = 208 g/mol - Finally, we find the relative atomic mass of element E using the mass of one mole of ECl2 and the mass of one mole of chlorine. A = (m - 2 * 35.5)/2 = (208 - 71)/2 = 68.5 - Therefore, the relative atomic mass of element E is 68.5, which means the correct answer is D) 64, since it is the closest option to the calculated value.