Chemistry worksheet on reaction rates and collision theory with a focus on the combustion of glucose, including a graph of energy changes in a reaction.

Problem Analysis:

The worksheet focuses on reaction rates and collision theory, using the combustion reaction of glucose as an example:
\[ \text{C}_6\text{H}_{12}\text{O}_6(s) + 6\text{O}_2(g) \rightarrow 6\text{H}_2\text{O}(g) + 6\text{CO}_2(g) \]

We will solve each question step by step.

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Question 1: What happens to the concentrations of:

#### a. \( \text{C}_6\text{H}_{12}\text{O}_6 \) & \( \text{O}_2 \) as the reaction proceeds?
- Answer: As the reaction proceeds, the concentration of \( \text{C}_6\text{H}_{12}\text{O}_6 \) (glucose) and \( \text{O}_2 \) (oxygen) decreases because they are reactants being consumed in the reaction.

#### b. \( \text{H}_2\text{O} \) & \( \text{CO}_2 \) as the reaction proceeds?
- Answer: As the reaction proceeds, the concentration of \( \text{H}_2\text{O} \) (water) and \( \text{CO}_2 \) (carbon dioxide) increases because they are products being formed in the reaction.

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Question 2: According to the collision theory, what 3 circumstances are needed for \( \text{C}_6\text{H}_{12}\text{O}_6 \) & \( \text{O}_2 \) to react?

- Answer: According to collision theory, three conditions must be met for a reaction to occur:
1. Collision frequency: The molecules must collide with sufficient frequency.
2. Activation energy: The colliding molecules must have enough energy (activation energy) to overcome the energy barrier for the reaction.
3. Orientation: The molecules must collide with the correct orientation to facilitate bond breaking and formation.

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Question 3: What is the activation energy for a chemical reaction?

- Answer: Activation energy is the minimum amount of energy required for a reaction to proceed. It represents the energy barrier that reactant molecules must overcome to form products. Without reaching this threshold, the reaction will not occur, even if the reactants collide.

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Question 4: Use the equation & the collision theory to explain the effect of various conditions on the reaction rate.

| Change in condition | Does this increase or decrease the rate of reaction? | Explain why |
|---------------------|----------------------------------------------------|-------------|
| a. Increasing the temperature | Increase | Higher temperature increases the kinetic energy of molecules, leading to more frequent and energetic collisions. This increases the likelihood of successful reactions. |
| b. Increasing the concentration of \( \text{C}_6\text{H}_{12}\text{O}_6 \) | Increase | A higher concentration of reactants means more molecules are present, increasing the frequency of collisions. |
| c. Decreasing the concentration of \( \text{O}_2 \) | Decrease | A lower concentration of oxygen reduces the number of collisions between \( \text{C}_6\text{H}_{12}\text{O}_6 \) and \( \text{O}_2 \), slowing down the reaction. |
| d. Increase the surface area by chewing up food in your mouth | Increase | Chewing increases the surface area of the reactants, allowing more molecules to come into contact and collide, thus speeding up the reaction. |
| e. Decreasing the temperature | Decrease | Lower temperature reduces the kinetic energy of molecules, decreasing the frequency and energy of collisions. This slows down the reaction. |
| f. Increasing the pressure in the container | Increase | Higher pressure brings molecules closer together, increasing their concentration and collision frequency. |
| g. Decreasing the concentration of \( \text{H}_2\text{O} \) | No effect | \( \text{H}_2\text{O} \) is a product, so its concentration does not affect the forward reaction rate directly. |
| h. Increasing the volume of the container where the reaction occurs | Decrease | Larger volume decreases the concentration of reactants, reducing collision frequency and slowing down the reaction. |
| i. Increasing the concentration of \( \text{CO}_2 \) | No effect | \( \text{CO}_2 \) is a product, so its concentration does not affect the forward reaction rate directly. |
| j. Using a catalyst (like salivary amylase) | Increase | A catalyst lowers the activation energy, allowing more collisions to result in successful reactions, thus speeding up the process. |

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Question 5: On the accompanying energy diagram, label the following terms:

#### a. Reactants
- Label: Point A (the starting point on the energy diagram).
#### b. Products
- Label: Point B (the ending point on the energy diagram).
#### c. Activation energy
- Label: The energy difference between the reactants (A) and the transition state (top of the hill).

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Question 6: On the graph to the right, draw and label what this diagram would look like if a catalyst was added to the reaction.

- Explanation: Adding a catalyst lowers the activation energy. The energy diagram would show the same reactants (A) and products (B), but the peak (transition state) would be at a lower energy level.

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Question 7: Graph reading

#### a. How much energy (\#) do the reactants have?
- Answer: The reactants have an energy level corresponding to point A on the graph.
#### b. How much energy (\#) do the products have?
- Answer: The products have an energy level corresponding to point B on the graph.
#### c. How much energy (\#) is required to activate this un-catalyzed reaction?
- Answer: The activation energy is the difference between the energy of the reactants (A) and the transition state (peak of the hill).
#### d. Is this reaction endothermic or exothermic? How do you know?
- Answer: The reaction is exothermic because the energy of the products (B) is lower than the energy of the reactants (A). Exothermic reactions release energy.

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Final Answer Summary:

1. a. Concentrations of \( \text{C}_6\text{H}_{12}\text{O}_6 \) and \( \text{O}_2 \) decrease.
b. Concentrations of \( \text{H}_2\text{O} \) and \( \text{CO}_2 \) increase.
2. Three circumstances: collision frequency, activation energy, and orientation.
3. Activation energy is the minimum energy required for a reaction to proceed.
4. Effects of conditions on reaction rate (explained above).
5. Labels: Reactants (A), Products (B), Activation energy (difference between A and peak).
6. Catalyst lowers the activation energy peak.
7. a. Energy of reactants (A).
b. Energy of products (B).
c. Activation energy (difference between A and peak).
d. Exothermic (products have lower energy than reactants).

Final Boxed Answer:
\[
\boxed{\text{See detailed explanations above.}}
\]