Reaction Rates and Equilibrium

What term is used to describe a chemical reaction in which the forward and reverse reaction rates are the same?

• A static equilibrium

• An equal equilibrium

• A dynamic equilibrium

What is the effect of decreasing the pressure on the following equilibrium 2NO(g) + O₂(g) ⇌ 2NO₂(g)?

• Less NO₂ will be produced

• Less NO and O₂ is formed

• No change will occur

What name is given to the minimum amount of energy needed by particles for them to react when they collide?

• Activation energy

• Catalytic energy

• Threshold energy

Tags

NGSS.HS-PS1-5

What is the name of the model which is used to explain how different factors affect the rate of a reaction?

• Particle theory

• Big Bang theory

• Collision theory

Tags

NGSS.HS-PS1-5

Why does a higher surface area of a solid reactant increase the reaction rate?

• It increases the density of the reactant

• It decreases the path length for diffusion

• It increases the number of available reactive sites

• It increases the activation energy required for the reaction

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

Tags

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.

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 of the following is true about reaction rates?

• increase as temperature decreases

• decrease when a catalyst is added

• increase as surface area increases

• decreases as reactant concentration increases

Tags

NGSS.HS-PS1-5

NGSS.HS-PS1-6

During a science fair, Abigail, Evelyn, and Priya conducted an experiment to observe the rate at which a sugar cube dissolves in water at room temperature. What is the unit of the reaction rate they observed?

• Molarity (M)

• Molarity per second (M/s)

• Kelvin (K)

• Joules (J)

Answer explanation

The unit of reaction rate in a chemical reaction is Molarity per second (M/s), which represents the change in concentration of reactants or products per unit time.

Tags

NGSS.HS-PS1-5