Sunday, February 7, 2010

Without doing any experiments, which of the following can you say must be true.?

The Haber reaction for the manufacture of ammonia is:


N2 + 3H2 2NH3





Without doing any experiments, which of the following can you say must be true.








The rate of disappearance of H2 is three times the rate of disappearance of N2.








1. Reaction rate = -螖[N2]/螖t.





2. The reaction is not an elementary reaction.





3. The reactant is first-order in N2.





4. The activation energy is positive.





5. 螖[H2]/螖t has a positive value.Without doing any experiments, which of the following can you say must be true.?
1) Impossible to say


2) Impossible to determine without experiment


3) Impossible to detemine


4) --%26gt; TRUE %26lt;--


5) Impossible to sayWithout doing any experiments, which of the following can you say must be true.?
1. looks good. That's the definition of rate.


2. For an elementary reaction to involve four reactant molecules would be highly unusual (impossible). So that's fine.


3. You don't know the order of the reaction without doing the concentration-dependent rate experiments.


4. Activation energies are always positive.


5. Hydrogen concentration is decreasing so this is false.
The first statement without a number is true because of the stoichiometric ratios in the reaction.





1. This is true because it is the definition of the rate.


2. This is very, very likely to be true but cannot be verified without experiment.


3. This is impossible to know without experiment.


4. This must be true because both N-N and H-H bonds must be broken in order to accomplish the reaction.


5. If the reaction is going in the forward direction, this is false because H2 would be disappearing.

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