Reaction Rate

Which one of the following is NOT a key concept of the collision theory:

• particles must collide in order to react

• particles must move slowly when they collide, otherwise they simply “bounce off” one another

• particles must collide with the proper orientation

• particles must collide with sufficient energy to reach the activated complex in order to react

Tags

NGSS.HS-PS2-3

Which one of the following factors does not affect the rate of a chemical reaction:

• humidity

• concentration

• temperature

• nature of the reactants

Tags

NGSS.HS-PS1-5

The rate of a chemical reaction normally

• increases as temperature decreases.

• decreases when a catalyst is added.

• increases as reactant concentration increases.

• decreases as reactant concentration increases.

Tags

NGSS.HS-PS1-5

Crushing a solid into a powder will increase reaction rate because:

• the particles will collide with more energy

• the orientation of colliding particles will be improved

• the activation energy barrier will be lowered

• the powdered form has more surface area

Tags

NGSS.HS-PS1-5

What happens to a catalyst in a reaction?

• It remains unchanged.

• It is incorporated into the reactants.

• It is incorporated into the products.

• It evaporates.

Which one of the following statements concerning rates of reactions is FALSE?

• The higher the activation energy barrier, the faster the reaction.

• Increasing the concentration of a reactant may increase the rate of a reaction.

• Adding a catalyst speeds up the rate of reaction for both the forward and reverse reactions.

• Increasing the concentration increases the rate of a reaction, because it increases the number of collisions.

Tags

NGSS.HS-PS1-5

Why does a higher concentration increase the rate of reaction?

• it increases the amount of reactants

• it lowers the activation energy

• it increases the energy of particle collisions

• it increases the frequency of particle collisions

Tags

NGSS.HS-PS1-5

Why does a higher temperature increase the rate of a reaction?

• it increases both the frequency and energy of particle collisions

• it only increases the frequency of particle collisions

• it only increases the energy of particle collisions

• it reduces the activation energy of the reaction

Tags

NGSS.HS-PS1-5

The energy needed by reactants for an effective collision is called the

• activation energy

• change in entropy

• change in enthalpy

• free energy

Which of these will NOT speed up the rate of reaction between a strip of magnesium and hydrochloric acid?

• twist the strip of magnesium
• grind up the strip of magnesium
• increase the concentration of the hydrocholoric acid
• increase the temperature of the hydrocholoric acid

Tags

NGSS.HS-PS1-5