CART Equilibrium and Reaction Rates 2 β Questions and Answers
Question 1: Reaction rate is defined as the change in concentration of a reactant or product per unit of:
- Volume
- Temperature
- Time (Correct answer)
- Pressure
Correct answer: Time
Reaction rate measures how quickly concentration changes over time, expressed as Ξ[concentration]/Ξtime.
Question 2: Which of the following will increase the rate of most chemical reactions?
- Decreasing temperature
- Decreasing reactant concentration
- Increasing surface area of solid reactants (Correct answer)
- Removing a catalyst
Correct answer: Increasing surface area of solid reactants
Increasing surface area exposes more reactant particles to collisions, increasing the frequency of effective collisions and the reaction rate.
Question 3: The activation energy of a reaction is the:
- Total energy released during the reaction
- Minimum energy required for reactants to form products (Correct answer)
- Energy difference between reactants and products
- Energy stored in chemical bonds
Correct answer: Minimum energy required for reactants to form products
Activation energy (Ea) is the minimum energy that colliding reactant molecules must have to successfully form products.
Question 4: According to collision theory, a reaction occurs when molecules collide with:
- Any energy at any orientation
- Sufficient energy and proper orientation (Correct answer)
- Sufficient energy only, regardless of orientation
- Any energy but only the correct orientation
Correct answer: Sufficient energy and proper orientation
Collision theory requires both sufficient kinetic energy (β₯ Ea) and the correct geometric orientation for a productive collision.
Question 5: In a reaction energy diagram, the activated complex (transition state) is found at the:
- Energy level of the reactants
- Energy level of the products
- Highest point on the energy diagram (Correct answer)
- Lowest point on the energy diagram
Correct answer: Highest point on the energy diagram
The transition state (activated complex) represents the highest energy arrangement of atoms during the reaction and sits at the peak of the energy diagram.
Question 6: If the concentration of a reactant is doubled and the reaction rate quadruples, the reaction is ________ order with respect to that reactant.
- Zero
- First
- Second (Correct answer)
- Third
Correct answer: Second
Rate β [A]^n; doubling [A] giving 4Γ rate means 2^n = 4, so n = 2 β the reaction is second order in that reactant.
CART Equilibrium and Reaction Rates 2
Reaction rate is defined as the change in concentration of a reactant or product per unit of: