Nitrogen monoxide reacts with hydrogen gas to form nitrogen gas and water (vapor). Write a balanced equation for this reaction. the reaction is experimentally found to be (approximately) first-order in H2 and second-order in NO. Write down the form of the experimentally-determined rate laws and the units of the rate constant.
2NO + 2H2 ==> N2 + 2H2O
rate = k(H2)(NO)2
units can be found here.
http://en.wikipedia.org/wiki/Reaction_rate_constant#Units
To write the balanced equation, we first need to understand the chemical formulas of the reactants and products involved:
Nitrogen monoxide: NO
Hydrogen gas: H2
Nitrogen gas: N2
Water vapor: H2O
The reaction can be represented as follows:
2 NO + 2 H2 → N2 + 2 H2O
Now, let's move on to the rate laws. The rate law expresses the relationship between the rate of a reaction and the concentration of the reactants. As stated in the question, the reaction is approximately first-order in H2 and second-order in NO.
The general form of a first-order rate law is:
Rate = k[A]^n
Where:
Rate is the rate of the reaction.
k is the rate constant.
[A] is the concentration of the reactant (in this case, H2).
n is the order of the reaction with respect to the reactant.
The general form of a second-order rate law is:
Rate = k[A]^n[B]^m
Where:
Rate is the rate of the reaction.
k is the rate constant.
[A] and [B] are the concentrations of the reactants (in this case, NO and H2).
n and m are the orders of the reaction with respect to the reactants.
Combining these observations with the given information, the rate law for this reaction can be written as follows:
Rate = k[H2]^1[NO]^2
The units of the rate constant can be determined by analyzing the overall reaction order. In this case, the overall reaction order is the sum of the individual orders for each reactant:
Overall reaction order (n + m) = 1 + 2 = 3
Hence, the units of the rate constant (k) will be (concentration)^-2 * time^-1.