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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. Reaction P starts at 16 °C and ends at 12 °C, indicating a temperature drop, which suggests that it absorbs heat, thus it is endothermic. Reaction Q starts at 15 °C and ends at 34 °C, indicating an increase in temperature, which shows that it releases heat; therefore, Q is exothermic. Reaction R remains at 17 °C, showing no temperature change, hence it is neither exothermic nor endothermic. Therefore, the exothermic reaction is Q.
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 indicated by the steepest part of the graph. To mark this, identify the point where the slope is at its highest, typically at the beginning of the graph, and place a cross in a circle at that point.
Step 3
Explain why powdered coal burns in air at a faster rate than lumps of coal.
Answer
Powdered coal burns at a faster rate than lumps of coal because of its increased surface area. The larger surface area allows more reactant particles to be available for reaction with oxygen in the air, leading to a higher rate of combustion. In contrast, lumps of coal have a reduced surface area, limiting the reaction and resulting in slower burning.
Step 4
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, perform the following steps:
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Set Up the Experiment: Measure a specific volume of hydrogen peroxide solution in a conical flask.
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Add the Catalyst: Introduce a small amount of manganese(IV) oxide to the hydrogen peroxide.
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Observe: Monitor the reaction by capturing the oxygen gas released, using a gas syringe or an upturned measuring cylinder submerged in water.
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Repeat without the Catalyst: Conduct a similar experiment without the manganese(IV) oxide to compare the rate of gas production.
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Results Analysis: Measure and record the volume of oxygen produced over a fixed time for both experiments. The faster rate of oxygen gas release with the catalyst indicates that it increases the reaction rate, and as its mass remains unchanged before and after the reaction, it demonstrates the second property of a catalyst.