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16. At room temperature and pressure, 8.0 g of oxygen and 20.0 g of gas X occupy the same volume. What is the molar mass of X?(Relative atomic mass : O=16.0; molar volume of gas at room temperature and pressure= 24.0 dm3)17. The compound X2S contains 58.9 % of X by mass. What is the relative atomic mass of X... 顯示更多 16. At room temperature and pressure, 8.0 g of oxygen and 20.0 g of gas X occupy the same volume. What is the molar mass of X? (Relative atomic mass : O=16.0; molar volume of gas at room temperature and pressure= 24.0 dm3) 17. The compound X2S contains 58.9 % of X by mass. What is the relative atomic mass of X ? (Relative atomic mass : S =32.1)
最佳解答:
By Avogadro's law, the same mole of particles occupy the same volume at the same condition. Molar mass of oxygen = 16.0 X 2 = 32.0 g/mol So, no. of mole of oxygen = mass / molar mass = 8.0 / 32.0 = 0.25 mol So, nol of mole of X = 0.25 mol So, molar mass of X = mass / no. of mole = 20.0 / 0.25 = 80.0 g/mol 17. Assume there are 100 g if X2S So, mass of X = 100 X 58.9% = 58.9 g So, mass of S = 100 - 58.9 = 41.1 g So, no. of mole of S = mass / molar mass = 41.1 / 32.1 = 1.28 mol So, no. of mole of X = 2 X 1.28 = 2.56 mol So, relative atomic mass of X = molar mass of X = mass / no. of mole = 58.9 / 5.26 = 23.0
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