Reaction Rates and Collision Theory

Which of the following is/are the fundamental idea(s) of collision theory?

• Molecules react by colliding together

• The effective collisions must occur with certain minimum amounts of energy 

• In a large sample, the greater the number of effective collisions, and the faster the rate of reaction

• All of the above

Tags

NGSS.HS-PS1-5

The following graph shows two different reaction pathways for the same overall reaction at the same temperature. Which pathway is slower and why?

• Red, because the activation energy is larger

• Blue, because the activation energy is lower

• both reaction progress at the same rate

Tags

NGSS.HS-PS1-4

Products will form faster if____________

• the particle size of the reactants are larger.

• temperature is decreased.

• concentration of the reactants are increased.

• the reaction is not stirred.

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NGSS.HS-PS1-5

What criteria must be met for reactant collisions to result in a successful product?

• The reactants must collide with each other

• The reactants must collide with enough energy and be in the right positions

• The reactants must have enough energy to form the activated complex

Tags

NGSS.HS-PS1-5

In a chemical reaction, if the concentration of reactants is increased, what happens to the reaction rate?

• It decreases

• It increases

• It remains unchanged

• It initially increases, then decreases

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NGSS.HS-PS1-5

Crushing a solid catalyst into finer particles before adding it to a reaction mixture will:

• Decrease the reaction rate.

• Have no effect on the reaction rate.

• Increase the reaction rate.

• Stop the reaction.

Answer explanation

Increasing the surface area of a solid reactant will increase the reaction rate by providing more area for collisions between reactant particles.

Tags

NGSS.HS-PS1-5

What is the significance of the activation energy in a chemical reaction?

• It is the energy released during the reaction

• It is the minimum energy required for reactants to transform into products

• It determines the color of the reaction mixture

• It is the energy required to break bonds in the products

In the process of baking bread, a catalyst affects the reaction by:

• Increasing the temperature of the oven.

• Decreasing the activation energy needed for the dough to rise.

• Increasing the concentration of yeast in the dough.

• Changing the equilibrium constant of the reaction.

Answer explanation

A catalyst affects a chemical reaction by decreasing the activation energy, making it easier for the reaction to occur.

Which among the following is NOT TRUE about the collision theory and the rate of reaction?

• higher temperature ---> faster particle movements ---> more collision

• higher concentration ---> more spaces between particles ---> more collision

• higher surface area ---> more particle interactions ---> more collision

Tags

NGSS.HS-PS1-5

The rate of a chemical reaction is NOT affected by which of the following:

• temperature

• concentration

• particle size (surface area)

• All of these affect reaction rates

Tags

NGSS.HS-PS1-5