Kinetics Question (spent over 7 hours on this)

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In summary, this problem involves a second order reaction where the initial concentration of AB is 0.210 M and the reaction mixture initially contains no products. Using the equation 1/[AB] = kt + 1/A initial, the concentration of both A and B is found to be 9.8×10−2 M after 80 seconds. The concentration of products is equal to the difference between the initial concentration of AB and the concentration of AB after 80 seconds.
  • #1
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Homework Statement


The following reaction was monitored as a function of time:
AB---> A + B
A plot of 1/[AB] versus time yields a straight line with slope 5.2×10−2 M \s.

If the initial concentration of AB} is 0.210 M, and the reaction mixture initially contains no products, what are the concentrations of {A} and {B} after 80 s?


Homework Equations



1/A = kt + 1 / A initial

The Attempt at a Solution



1/A = (5.2x10^-2)(80 s) + 1/0.21 M
*When I did this equation it was wrong. The correct answer was that the concentration of both A and B=9.8×10−2,9.8×10−2. Please tell me what I am doing wrong. Thanks!
 
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  • #2
[tex]k=\frac{rate}{[AB]}[/tex]

and [AB] at t=0 can be used because k is a constant ratio. The rate is the slope of the line. However, the problem appears to have an error:

[tex]\frac{1/[AB]}{t}=5.2x10^{-2}M/s[/tex]

The units should be

[tex]\frac{1}{Ms}[/tex]

If 1/[AB] vs. time is linear then k is not linear. Is this a first order reaction?
 
  • #3
Thanks for your response. I think the rate is second order because given was: Rate=k,[AB]^2

I just plugged in those numbers for first order and I am still getting the answer wrong. This question is frustrating me to the max. Any help would be hugely appreciated.
 
  • #4
Since it's a second order reaction, your equation for 1/[AB] is correct. Use conservation of mass. Your answer gives the concentration of AB after 80 seconds so this means what was converted is

.21 - [AB] = 9.8 x 10-2 M = concentration of products.
 
Last edited:

Related to Kinetics Question (spent over 7 hours on this)

1. What is kinetics and why is it important?

Kinetics is the study of the rate of chemical reactions and the factors that affect it. It is important because it helps us understand and control the speed of reactions, which is crucial in fields such as drug development, industrial processes, and environmental studies.

2. What factors affect the rate of a chemical reaction?

The rate of a chemical reaction can be affected by factors such as temperature, concentration of reactants, surface area, presence of a catalyst, and the nature of the reactants and products.

3. How do you calculate the rate of a chemical reaction?

The rate of a chemical reaction can be calculated by measuring the change in concentration of reactants or products over time. It can also be determined by using the rate law, which describes the relationship between the rate of a reaction and the concentrations of the reactants.

4. What is a catalyst and how does it affect the rate of a chemical reaction?

A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It does this by providing an alternative pathway with a lower activation energy, making it easier for the reaction to occur. This results in a faster rate of reaction.

5. How does temperature affect the rate of a chemical reaction?

Increasing the temperature of a reaction typically leads to an increase in the rate of reaction. This is because higher temperatures provide more kinetic energy to the reactant molecules, making them move faster and collide with greater energy. This increases the likelihood of successful collisions and therefore, the rate of reaction.

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