How Does Changing Concentration Affect the Rate of a Chemical Reaction?

[tensirk]

Homework Statement

The reaction 2NO(g) + O₂(g) ---> 2NO₂(g) is second order in NO and first order in O₂.
When [NO] = 1 M and [O₂] = 1.9 M, the observed rate of disappearance of NO is 0.00017670 M/s.

I have already found the value of the rate constant to be 2. I found that the units of the rate constant are M^-2s^-1. I lastly found that the rate of the reaction would increase if the concentration of NO were increased by a factor of 1.4.

Now I am having a lot of trouble figuring out these last two problems:
1. By what factor would the rate of reaction of NO increase? [if it were increased by a factor of 1.4]
2. What is the rate of reaction when [NO] = 0.1 M and [O₂] = 0.19 M?

Homework Equations

Honestly, I don't even know where to begin in terms of equations for these two problems.

The Attempt at a Solution

I think where I'm having trouble is understanding what "second order in NO" means. Any guidance on these problems would be MUCH appreciated, as I feel completely lost. Thanks in advance!

 

[Borek]

v=k[O₂][NO]²

 

[cep]

The "orders" are the powers to which the concentrations are raised. These come from the stoichiometric ratios of the reactants.

 

[sjb-2812]

The "orders" are the powers to which the concentrations are raised. These come from the stoichiometric ratios of the reactants.

Not necessarily. For instance, the rate of halogenation of acetone is proportional to the concentration of acid, and is independent of the concentration of halogen.

 

[DeeNos]

As a scientist, it is important to understand the fundamentals of chemical reactions, particularly rates of reactions. In this problem, we are dealing with a second order reaction, which means that the rate of the reaction is directly proportional to the square of the concentration of NO. This also means that if the concentration of NO is increased by a factor of 1.4, the rate of the reaction will increase by a factor of (1.4)^2 = 1.96. Therefore, the rate of the reaction would increase by 1.96 times.

To answer the second question, we can use the rate law equation: rate = k[NO]^2[O2]. Plugging in the given concentrations, we get:

rate = (2 M-2s-1)(0.1 M)^2(0.19 M) = 0.0038 M/s

Therefore, when [NO] = 0.1 M and [O2] = 0.19 M, the rate of the reaction is 0.0038 M/s. I hope this helps clarify the concepts of second order reactions and how to approach these types of problems. If you still have trouble, I suggest reviewing the fundamentals of chemical kinetics and practicing more problems. Good luck!