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1) Calculate total number of atoms in 22g aluminium sulphate2a) Find the empirical formulae of compounds with the following composition by mass:i) 75% carbon, 25% hydrogenii) 36.5% sodium, 25.4% sulphur, 38.1% oxygenb) when sodium is heated in air, it catches fire and forms an oxide. If the sample is... 顯示更多 1) Calculate total number of atoms in 22g aluminium sulphate 2a) Find the empirical formulae of compounds with the following composition by mass: i) 75% carbon, 25% hydrogen ii) 36.5% sodium, 25.4% sulphur, 38.1% oxygen b) when sodium is heated in air, it catches fire and forms an oxide. If the sample is weighed before and after reaction, it is found to increase in mass by approximately 35%. On the other hand, when sodium is heated in pure oxygen, the reaction takes place more readily and the increase in mass is about 70%. Work out the simplest formulae of the two oxides of sodium. 我想知里2條點計? 同埋有冇d相關題目嘅網址俾埋我吖唔該
最佳解答:
1) Molar mass of Al2(SO4)3 = 27x2 + (32.1 +16x4)x3 = 342.3 g/mol No. of moles of Al2(SO4)3 = 22 / 342.3 =0.0643 mol No. of moles of atoms in 1 mole of Al2(SO4)3 =2 + (1 + 4)x3 = 17 mol No. of atoms = 0.0643 x 17 x (6.02 x 1023) = 6.58 x 1023 ===== 2a) i) Mole ratio C : H = 75/12 : 25/1 = 6.25 : 25 = 1 : 4 Empirical formula = CH4 ii) Mole ratio Na : S : O = 36.5/23 : 25.4/32.1 : 38.1/16 = 1.59 : 0.791 : 2.38 = 2: 1 : 3 Empirical formula = Na2SO3 2b) For the oxide formed when sodium is heated in air : Mole ratio Na : O = 100/23 : 35/16 = 4.35 : 2.19 = 2 : 1 Empirical formula = Na2O For the oxide formed when sodium is heated in pure oxygen : Molar ratio Na : O = 100/23 : 70/16 = 4.35 : 4.38 = 1 : 1 Empirical formula = NaO
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chem mole 數!!發問:
1) Calculate total number of atoms in 22g aluminium sulphate2a) Find the empirical formulae of compounds with the following composition by mass:i) 75% carbon, 25% hydrogenii) 36.5% sodium, 25.4% sulphur, 38.1% oxygenb) when sodium is heated in air, it catches fire and forms an oxide. If the sample is... 顯示更多 1) Calculate total number of atoms in 22g aluminium sulphate 2a) Find the empirical formulae of compounds with the following composition by mass: i) 75% carbon, 25% hydrogen ii) 36.5% sodium, 25.4% sulphur, 38.1% oxygen b) when sodium is heated in air, it catches fire and forms an oxide. If the sample is weighed before and after reaction, it is found to increase in mass by approximately 35%. On the other hand, when sodium is heated in pure oxygen, the reaction takes place more readily and the increase in mass is about 70%. Work out the simplest formulae of the two oxides of sodium. 我想知里2條點計? 同埋有冇d相關題目嘅網址俾埋我吖唔該
最佳解答:
1) Molar mass of Al2(SO4)3 = 27x2 + (32.1 +16x4)x3 = 342.3 g/mol No. of moles of Al2(SO4)3 = 22 / 342.3 =0.0643 mol No. of moles of atoms in 1 mole of Al2(SO4)3 =2 + (1 + 4)x3 = 17 mol No. of atoms = 0.0643 x 17 x (6.02 x 1023) = 6.58 x 1023 ===== 2a) i) Mole ratio C : H = 75/12 : 25/1 = 6.25 : 25 = 1 : 4 Empirical formula = CH4 ii) Mole ratio Na : S : O = 36.5/23 : 25.4/32.1 : 38.1/16 = 1.59 : 0.791 : 2.38 = 2: 1 : 3 Empirical formula = Na2SO3 2b) For the oxide formed when sodium is heated in air : Mole ratio Na : O = 100/23 : 35/16 = 4.35 : 2.19 = 2 : 1 Empirical formula = Na2O For the oxide formed when sodium is heated in pure oxygen : Molar ratio Na : O = 100/23 : 70/16 = 4.35 : 4.38 = 1 : 1 Empirical formula = NaO
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