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  1. Main ideal of why cpd has to be formed: When elements or atoms do not form any bonds, the energy of individal atom/element has a very high energy so that they are unstable. In order to become more stable, they tend to form bonds no matter...

    分類:科學及數學 > 化學 2009年03月14日

  2. • Add (pipette) 50.0 cm3 of water into a polystyrene cup. • Weigh a sample of ammonium nitrate in a weighing bottle. • Stir and record the temperature to the nearest 0.1oC every half minute for 2½½ minutes. • At precisely 3 minutes...

    分類:科學及數學 > 化學 2011年04月03日

  3. 1. First, you've wrong calculations on positive-negative values. your first equation should be enthalpy change = 3 x -(std. ent. change of FORMATION of hydrazine) + 4 x (std. ent. change of FORMATION of ammonia) = -3 x (+50.4) + 4 x (-46.3) = -290.1 kJ/mol...

    分類:科學及數學 > 化學 2012年05月28日

  4. 1) Molar mass of the fuel mixture = 27 + 14 + 4 + 35.5 + 4 x 16 = 144.5 Hence no. of moles present in 1 g of mixture = 1/144.5 = 0.00692 mole From the equation, 3 moles of fuel mixture can give an energy of 2680 kJ and hence 1 g can give: 0.00692 x 2680/3 = 6.18 kJ 2) Vol. of...

    分類:科學及數學 > 化學 2012年04月13日

  5. should be kJ mol-1 for the unit of standard enthalpy change you can also follow the unit given in the question

    分類:科學及數學 > 化學 2007年12月09日

  6. Firstly, you need to know the term entropy S Entropy is the tendency of a substance to acheive randomness. For diamond , each carbon atom is tetrahedrally bonded to four other carbon atoms(sp3 hybridized). All the four bonds...

    分類:科學及數學 > 化學 2007年10月26日

  7. Basic knowledge : H+(aq) + OH-(aq) → H2O(l) mole ratio H+(aq) : OH-(aq) : H2O(l) = 1 : 1 : 1 Enthalpy change of neutralization is defined as the enthalpy change in the standard state when 1 mole of water is produced from the...

    分類:科學及數學 > 化學 2007年03月13日

  8. 1. CO2(g) + 2H2O(l) → CH3OH(l) + (3/2)O2(g) .. ΔH = -(-7266) kJ/mol C(graphite) + O2(g) → CO2(g) .. ΔH = -393.5 kJ/mol 2H2(g) + O­2(g) → 2H2O(l...

    分類:科學及數學 > 化學 2009年11月07日

  9. i) Both HCl and HNO3 are strong acid, which nearly completely dissociate in water, given the same amount of H+ in a standard solution. All H+ given out will carry out the reaction: H+ + OH- → H2O -57.3KJ/mol So...

    分類:科學及數學 > 化學 2011年05月12日

  10. Balance the equation: Ca(OH)2 + 2 HCl -------> CaCl2 + 2H2O (a) Ca(OH)2 has 0.0005 mole, HCl has 0.00025 mole. Therefore, all HCl would be consumed and Ca(OH)2...

    分類:科學及數學 > 化學 2009年11月06日