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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 reaction is exothermic, we look at the temperature changes recorded for each reaction. An exothermic reaction is characterized by a decrease in temperature as it releases heat.
- Reaction P starts at 16°C and finishes at 12°C, indicating a drop in temperature, hence it is exothermic.
- Reaction Q starts at 15°C and increases to 34°C, indicating an endothermic reaction due to heat absorption.
- Reaction R remains constant at 17°C throughout, indicating no heat change.
Thus, Reaction P is exothermic.
Step 2
Place a cross in a circle on the graph to show where the reaction is at its fastest rate.
Answer
The fastest rate of reaction is typically indicated where the steepest slope of the graph occurs, which represents the highest volume of hydrogen production over time. A cross should be placed at that point on the graph.
Step 3
On the graph, sketch a line to show the results you would expect in this case.
Answer
In this case, when the hydrochloric acid is more dilute, the reaction will be slower than in the original experiment. Therefore, the expected line on the graph should be drawn below the initial line, indicating a slower accumulation of hydrogen gas over time compared to the original reaction.
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, which facilitates more exposure to oxygen. This increased surface area allows for quicker combustion as more air can access the coal simultaneously, resulting in a faster reaction rate.
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:
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Setup: Mix hydrogen peroxide with manganese(IV) oxide in a flask and observe the reaction. Measure the volume of oxygen gas produced over time to indicate the rate of reaction.
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Observation of Reaction Rate: The presence of manganese(IV) oxide should accelerate the decomposition of hydrogen peroxide, resulting in a faster production of gas compared to a control experiment without the catalyst.
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End of Reaction: After the reaction, weigh the manganese(IV) oxide to show that its mass remains unchanged, confirming it does not get consumed in the reaction. This demonstrates both the increased reaction rate and that the catalyst retains its mass after the reaction.