Kinetics Worksheet: Temperature, Concentration, and Reaction Rates

Part A: Analyzing Temperature and Reaction Rate Data

1. The table below shows data from an experiment measuring the time required for a reaction to complete at different temperatures.

a) Calculate the reaction rate (1/time) for each temperature.

b) Create a graph with temperature on the x-axis and reaction rate on the y-axis. Describe the relationship.

c) Create a second graph with 1/T (where T is temperature in Kelvin) on the x-axis and ln(rate) on the y-axis. What does the shape of this graph tell you about the relationship?

Part B: Collision Theory and Temperature Effects

2. According to collision theory, for a reaction to occur, particles must:

   a) ______________________

   b) ______________________

3. The Arrhenius equation relates reaction rate to temperature: $k = Ae^{-E_a/RT}$

   a) Identify what each variable represents:

   • $k$ =
   • $A$ =
   • $E_a$ =
   • $R$ =
   • $T$ =

   b) A reaction has an activation energy of 58.5 kJ/mol. Calculate how many times faster this reaction would proceed at 35°C compared to 25°C. Show your work using the Arrhenius equation.

4. Explain quantitatively why a 10°C increase in temperature typically causes a reaction rate to approximately double. Use the Arrhenius equation in your explanation.

Part C: Concentration Effects on Reaction Rate

5. For the reaction: 2A + B → C, the rate law is determined to be: rate = k[A][B]²

   a) If the concentration of A is doubled, how will the rate change? Prove mathematically.

   b) If the concentration of B is halved, how will the rate change? Prove mathematically.

   c) If both [A] and [B] are tripled, how will the rate change? Prove mathematically.

6. For a zero-order reaction: rate = k For a first-order reaction: rate = k[A] For a second-order reaction: rate = k[A]²

   Complete the table showing how the reaction rate would change in each scenario:

Part D: Experimental Design

7. Design an experiment to determine the effect of temperature on the rate of the reaction between sodium thiosulfate and hydrochloric acid: Na₂S₂O₃(aq) + 2HCl(aq) → 2NaCl(aq) + H₂O(l) + SO₂(g) + S(s)

   Include:

   • Materials needed
   • Independent and dependent variables
   • Control variables
   • Step-by-step procedure
   • Data collection method
   • Safety precautions

8. Design an experiment to determine the order of reaction with respect to a reactant in the decomposition of hydrogen peroxide catalyzed by potassium iodide: 2H₂O₂(aq) → 2H₂O(l) + O₂(g)

   Include:

   • How you would vary concentration
   • How you would measure reaction rate
   • How you would analyze your data to determine reaction order

Part E: Application of the Arrhenius Equation

9. The activation energy for a reaction is 75.3 kJ/mol.

   a) Calculate the rate constant at 25°C if the rate constant at 45°C is 3.6 × 10⁻³ s⁻¹.

   b) Draw an energy diagram for an exothermic reaction, labeling:

   • Reactants and products
   • Activation energy
   • Transition state
   • Overall energy change (ΔH)

   c) On the same diagram, draw a second curve showing how a catalyst would affect the reaction pathway.

10. A food company needs to determine the shelf life of a product. The spoilage reaction has an activation energy of 84 kJ/mol.

    a) If the product lasts 30 days at 5°C (refrigerated), how long would it last at 25°C (room temperature)?

    b) Explain using the Arrhenius equation why refrigeration extends the shelf life of food.

Self-Assessment

Rate your understanding of each learning outcome: - I can analyze experimental data to determine temperature-rate relationships: □ Confident □ Somewhat confident □ Need more practice - I can use collision theory to explain temperature effects: □ Confident □ Somewhat confident □ Need more practice - I can predict concentration effects using mathematical relationships: □ Confident □ Somewhat confident □ Need more practice - I can design experiments to test kinetics factors: □ Confident □ Somewhat confident □ Need more practice - I can apply the Arrhenius equation: □ Confident □ Somewhat confident □ Need more practice