Chemical Reaction Rates and Energy

What is necessary for a chemical reaction to occur between molecules?

• Molecules must be in a liquid state.

• Molecules must collide with sufficient energy and proper orientation.

• Molecules must be in a gaseous state.

• Molecules must be at a high temperature.

How does increasing the concentration of reactants affect the reaction rate?

• It increases the reaction rate by increasing collision frequency.

• It has no effect on the reaction rate.

• It decreases the reaction rate.

• It changes the reaction from endothermic to exothermic.

Why does increasing temperature generally increase the rate of a chemical reaction?

• It decreases the energy of the molecules.

• It increases the frequency and force of molecular collisions.

• It changes the state of the reactants to gas.

• It decreases the concentration of reactants.

What is the relationship between energy changes and reaction rates?

• Energy changes do not affect reaction rates.

• The relationship is complex and not solely dependent on being exothermic or endothermic.

• All endothermic reactions are slow.

• All exothermic reactions are fast.

What is the transition state in a chemical reaction?

• The state where no energy is required.

• The highest energy arrangement of atoms during a reaction.

• The state where reactants are fully converted to products.

• The lowest energy state of the reactants.

What is activation energy?

• The energy at which a reaction stops.

• The energy absorbed by the products.

• The energy released during a reaction.

• The energy required to start a reaction.

Why might a reaction with a high activation energy not occur at room temperature?

• The reactants are not in the correct state.

• The activation energy is too high to be overcome without additional energy.

• The reaction is endothermic.

• The products are unstable.

What is a reaction energy diagram used for?

• To measure the temperature of a reaction.

• To determine the concentration of reactants.

• To illustrate the energetic changes during a chemical reaction.

• To show the physical state of reactants and products.

How do catalysts affect chemical reactions?

• They slow down the reaction rate.

• They increase the activation energy required.

• They change the reaction from exothermic to endothermic.

• They decrease the activation energy required.

What role do enzymes play in living organisms?

• They convert energy into matter.

• They increase the activation energy of reactions.

• They slow down chemical reactions.

• They act as catalysts to speed up reactions.