Reaction Rates

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

How does a catalyst work in speeding up a reaction?

• By lowering the activation energy or reaction

• by giving them more energy

• by making them more available

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

Why don't all collisions between particles cause a reaction?

• the particles also need to collide with a catalyst
• not all the particles collide with enough energy
• not all the particles collide at a high enough temperature
• the particles need to collide with each other twice

Grinding a seltzer tablet into powder increases the rate of reaction due to increased

• concentration
• surface area
• temperature
• reactants

What are the units of k for the rate law: Rate = k[A][B]², when the concentration unit is mol/L?

• s^-1

• s

• L mol^-1 s^-1 or M^-1s^-1

• L² mol^-2 s^-1 or M^-2s^-1

• L² s² mol^-2 or M²s²

When [B] is decreasing at 0.5 molL-1s-1, how fast is [A] decreasing for A +2B  $\rightarrow$   C ?

• 0.5

• 0.25

• 1.0

• 1.25

For the reaction:

4NH₃(g) + 5O₂(g) → 4 NO(g) + 6H₂O(g)

the rate of disappearance of oxygen is 0.020 M/s. What is the rate of formation of H₂O?

• 0.03 Ms^-1

• 0.02 Ms^-1

• 0.017 Ms^-1

• 0.024 Ms^-1

What is the rate exponent for A?

• 0
• 1
• 2

What is the rate exponent for B?

• 0
• 1
• 2