AP Chemistry : Kinetic Molecular Theory
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Example Questions
Example Question #1 : Kinetic Molecular Theory
Two moles of nitrogen gas are kept in a glass container. The temperature of the gas is 400K.
What is the kinetic energy of the gas?
Using the equation 
Example Question #1 : Kinetic Molecular Theory
Which of the following is not an assumption of the kinetic molecular theory of gases?
Collisions between gas particles are elastic
The kinetic energy of gas particles are different for all gases at a certain temperature
Gas particles are in random, continuous motion
The volumes of the particles of a gas are negligible
Gas particles do not experience attractions/repulsions to other particles
The kinetic energy of gas particles are different for all gases at a certain temperature
The kinetic molecular theory of gases states that the average kinetic energy of gas particles is proportional to temperature, and it is the same for all gases at a given temperature. This is the opposite of what is stated in the answer choice.
Example Question #1 : Kinetic Molecular Theory
Why does a higher temperature result in a faster reaction?
It increases the pressure of the reactants
It increases the surface area for reactions
It increases the number of effective molecular collisions
It lowers the activation energy for a reaction
It helps orient reactants into the correct position to react
It increases the number of effective molecular collisions
The temperature of a system can be manipulated to increase the reaction rate. The temperature affects the rate of the reaction because as temperature increases, so does the average kinetic energy. This means that molecules (reactants) are moving around more quickly, resulting in more frequent molecular collisions, resulting in an increased rate of product formation.
Example Question #1 : Kinetic Molecular Theory
Which of the following statements in not an assumption made in kinetic molecular theory?
Much of the volume of the container is empty space
No attractive forces exist between gas molecules
The average kinetic energy of gas molecules is a function of both temperature and pressure
Collisions between gas molecules and the container are perfectly elastic
The average kinetic energy of gas molecules is a function of both temperature and pressure
The average kinetic energy is considered to be a sole function of temperature; pressure is not a factor. All of the other statements are assumptions of kinetic molecular theory.
Example Question #1 : Kinetic Molecular Theory
The reaction 
What are the units of the rate constant, 
Recall that 
Dividing both sides by 
Example Question #1 : Kinetic Molecular Theory
Consider the following first order reaction
Where k is the rate constant.
and the initial concentrations of A and B are
What is the percent conversion after 500 seconds? Round to the nearest percent.
For a first order reaction,
Integrating both sides gives
Where 
Solving for 
Initially 
At 
Percent conversion is calculated as follows:
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