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This question is about three different reactions, P, Q and R - Edexcel - GCSE Chemistry - Question 6 - 2016 - Paper 1
Question 6
This question is about three different reactions, P, Q and R. As the reactions are carried out, the initial and final temperatures are recorded. | reaction | initi... show full transcript
Worked Solution & Example Answer:This question is about three different reactions, P, Q and R - Edexcel - GCSE Chemistry - Question 6 - 2016 - Paper 1
Step 1
Explain which of these reactions, P, Q or R is exothermic.
Answer
To determine which of the reactions is exothermic, we need to compare the initial and final temperatures. An exothermic reaction is one that releases heat, leading to an increase in temperature of the surroundings.
- Reaction P: Initial temperature is 16°C and final temperature is 12°C, indicating a loss of heat.
- Reaction Q: Initial temperature is 15°C and final temperature is 34°C, indicating a gain of heat, thus it is exothermic.
- Reaction R: The initial and final temperatures are both 17°C, showing no heat change.
Therefore, reaction Q is the only exothermic reaction.
Step 2
Place a cross in a circle on the graph to show where the reaction is at its fastest rate.
Answer
To indicate the fastest rate of reaction on the provided graph, a cross should be placed at the steepest point of the curve, representing the maximum increase in volume of hydrogen gas generated with respect to time.
Step 3
On the graph, sketch a line to show the results you would expect in this case.
Answer
When the hydrochloric acid is more dilute, the reaction with magnesium ribbon will proceed more slowly, resulting in a gradual increase in the volume of hydrogen gas collected. On the graph, the new line should be less steep than the original, illustrating a slower reaction rate over time.
Step 4
Explain why powdered coal burns in air at a faster rate than lumps of coal.
Answer
Powdered coal has a significantly larger surface area than lumps of coal, which increases the rate of reaction with oxygen in the air. The greater surface area allows more coal particles to come into contact with oxygen, facilitating a faster combustion process. Additionally, the increased number of collisions between coal particles and oxygen molecules leads to a higher reaction rate, making powdered coal burn more effectively.
Step 5
Using hydrogen peroxide solution and manganese(IV) oxide, describe experiments to show that manganese(IV) oxide has these properties when used as a catalyst in this reaction.
Answer
To investigate the catalytic properties of manganese(IV) oxide in the decomposition of hydrogen peroxide, the following steps can be conducted:
- Set-Up the Reaction: In a conical flask, add a measured amount of hydrogen peroxide solution.
- Add Manganese(IV) Oxide: Introduce a small amount of manganese(IV) oxide to the flask and observe the reaction.
- Measure Gas Production: Use a gas syringe or an inverted measuring cylinder to capture the oxygen gas produced. Record the volume of gas produced at regular time intervals.
- Repeat Without Catalyst: Conduct the same experiment without manganese(IV) oxide to serve as a control.
- Document Findings: Compare the volume of gas produced in both scenarios.
Conclusion: In the presence of manganese(IV) oxide, the volume of oxygen produced will be considerably higher over the same time period, demonstrating that the catalyst increases the rate of the reaction. At the end of the experiment, the mass of manganese(IV) oxide should be the same, confirming that it is unchanged, thus fulfilling both properties of a catalyst.