Anonymous asked in Science & MathematicsAgriculture · 2 months ago

calculate enthalpy and reaction?

The reaction is performed by forming 6 moles of nitrogen dioxide in a perfect calorimeter (Ccal = 0.0 J/K) that contains 3000. grams of water (sH2O = 4.184 J/g∙K).  The water cools by 16.18 K.  Calculate the enthalpy (ΔH) in kJ enthalpy of reaction (ΔrxnH) in kJ/mol.  Assume the reaction goes to completion.

1 Answer

  • 2 months ago

    Calculate the heat that the water lost:

    q = m c Delta T

    q = 3000 g (4.184 J/gK (-16.18 K) = -2.031X10^5 J = -203.1 kJ

    So, the reaction was endothermic and absorbed +203.1 kJ

    ΔHrxn = +203.1 kJ / 6 mol = 33.8 kJ/mol

    (Properly, your answer can have only 1 significant figure, unless you assume that you formed 6.000 moles of NO2. In that case, you might be able to report ΔHrxn = +33.85 kJ/mol)

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