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chemistry (急)10點

發問:

An oxide element X has the formula X2O3.10.2g of this oxide contains 5.4g of X.what is relative atomicmass of X?(Relative atomic mass :O=16.0 A.12 B.18.0 C.27.0 D.36.0

最佳解答:

Mass of oxygen in the compound = 10.2 - 5.4 = 4.8 g Relative atomic mass of oxygen= 16.0 No. of mole of oxygen = 4.8 / 16.0 = 0.3 mol No. of mole of X = 0.3 X 2/3 = 0.2 mol Mass of X in the compound = 5.4 g So, relative atomic mass of X = 5.4 / 0.2 = 27.0 So, the answer is C. 27.0

其他解答:

Mass of oxygen in compound = 10.2-5.4=4.8g no. of mole of oxygen = mass/molar mass= 4.8/16=0.3mol From the formla X2O3, the mole ratio of X to O is 2:3 so, no. of mole of X = 0.2mole Relative atomic mass of X = 5.4/0.2 = 27 The answer is C

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