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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 | initia... 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 reaction is exothermic, we observe the temperature change in each reaction. An exothermic reaction releases energy, resulting in an increase in temperature of the surroundings.
- For reaction P: Initial temperature is 16°C, and final temperature is 12°C. This shows a decrease in temperature, indicating it is an endothermic reaction.
- For reaction Q: Initial temperature is 15°C, and final temperature is 34°C. The increase in temperature indicates that this reaction releases heat, making it exothermic.
- For reaction R: Initial temperature is 17°C, and final temperature is 17°C. There is no temperature change, so it cannot be classified as exothermic or endothermic.
Thus, the exothermic reaction among P, Q, and R is Q.
Step 2
Place a cross in a circle on the graph to show where the reaction is at its fastest rate.
Answer
On the provided graph, the fastest rate of the reaction typically occurs at the steepest slope. In this case, the fastest rate is around 20 seconds, where the volume of hydrogen rises sharply. A cross should be placed in a circle at that point.
Step 3
On the graph, sketch a line to show the results you would expect in this case.
Answer
When hydrochloric acid is more dilute, the rate of reaction decreases, leading to a slower increase in the volume of hydrogen gas produced. Therefore, the new line on the graph should be less steep than the original line, indicating a gradual increase over a longer time frame.
Step 4
Explain why powdered coal burns in air at a faster rate than lumps of coal.
Answer
Powdered coal has a larger surface area compared to lumps of coal, allowing for more points of contact with air. This increased surface area facilitates a quicker reaction with oxygen, enabling powdered coal to burn more rapidly. Additionally, the finer particles allow for better mixing with the air, enhancing the combustion process.
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 demonstrate the catalytic properties of manganese(IV) oxide in the decomposition of hydrogen peroxide:
- Set Up: Prepare two test tubes, one containing hydrogen peroxide and manganese(IV) oxide, and the other containing only hydrogen peroxide.
- Observation of Rate: Observe the production of gas in both test tubes. The tube with manganese(IV) oxide should produce gas (oxygen) much faster due to the catalyst, while the tube without will produce gas at a slower rate.
- Mass Measurement: After the reaction, measure the mass of manganese(IV) oxide in the first tube. It should remain unchanged, demonstrating that a catalyst does not alter its own mass at the end of the reaction.
- Conclusion: The rapid production of gas shows that manganese(IV) oxide increases the reaction rate, confirming its catalytic properties.