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F.4 chem,, 關於mole

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問題:A sample of impure copper of 28.5g is dissolved in concentrated nitric acid. The mixture is heated to dryness to give copper(II) nirtrate. On strong heating, 31.80g of copper (II) oxide form. Calculate the percentage by mass of copper in the sample.(Relative atomic masses: O=16.0, Cu=63.5)答案: 89.1%請寫出d... 顯示更多 問題: A sample of impure copper of 28.5g is dissolved in concentrated nitric acid. The mixture is heated to dryness to give copper(II) nirtrate. On strong heating, 31.80g of copper (II) oxide form. Calculate the percentage by mass of copper in the sample. (Relative atomic masses: O=16.0, Cu=63.5) 答案: 89.1% 請寫出d step.. 同埋解釋比我聽.. thz! 更新: to terrymyh18:: 請問Cu+1/2O2-->CuO點黎..? mole ratio is 1:1又係邊道搵到?

最佳解答:

The number of mole of copper(II) oxide form=31.8/(63.5+16) =0.4mol Cu+1/2O2-->CuO The mole ratio is 1:1 The mass of copper used = 0.4x63.5 =25.4g The percentage by mass of copper in the sample =25.4/28.5x100% =89.1% 2009-02-14 21:44:54 補充: Cu+1/2O2-->CuO this formula is not actully react like this in the above question. But it shown that in one mole CuO there should be contain one mole Cu. so the mole ratio is 1:1 2009-02-14 21:44:58 補充: At last,there are 31.8 g CuO,we find the mole of CuO.then we find the mole number of Cu,then we can find the mass of Cu iniital by multiply the relaive atomic mass/

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