Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: drew k. on April 07, 2004, 02:25:18 PM

i have a couple of questions.
1.if the heat of reaction(delta H) is 1023kJ/mole and the entropy(delta S) is 324j/mole.k. over what temperature range will this reacttion be spontaneous(deltaG is negative) ?
2.what would the equilibrium equation be for this reaction?
2NO2+7H2>2NH3+4H2O
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3. what would the reaction of elemental sodium with chlorine gas to make table salt(NaCl)?

i have a couple of questions.
1.if the heat of reaction(delta H) is 1023kJ/mole and the entropy(delta S) is 324j/mole.k. over what temperature range will this reacttion be spontaneous(deltaG is negative) ?
2.what would the equilibrium equation be for this reaction?
2NO2+7H2>2NH3+4H2O
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3. what would the reaction of elemental sodium with chlorine gas to make table salt(NaCl)?
1. ?G_{rxn} = ?H_{rxn}  T?S_{rxn}. All you need to do is calculate the temperatures that will give a ?G_{rxn}.
2. To calculate the equilibrium constant for an equation, you need to take the product of the the equilibrium concentrations of the products and divide it by the product of the equilibrium concentrations of the reactants. Now, since all of these molecules are gaseous, you'll need to remember that the concentrations will probably be given in terms of partial pressure. Therefore, you'll need to convert your K_{p} to a K_{c} or viceversa. (K_{p} is calculated the same way as K_{c}, only you use the partial pressures instead of the molarity). So, if you calculated your K_{p} you may need to convert that to K_{c} using the following equation:
K_{p} = K_{c}(RT)^{?n}
R is the universal gas constant, T is the temperature, and ?n is the (#moles gaseous products)  (#moles gaseous reactants).
3). The reaction would be very violent and throw sodium chloride all over the place. ;D