Hydrogen peroxide (H₂O₂) decomposes rapidly in the presence of a suitable catalyst to form water and a colourless gas - Leaving Cert Chemistry - Question 3 - 2014
Question 3
Hydrogen peroxide (H₂O₂) decomposes rapidly in the presence of a suitable catalyst to form water and a colourless gas. The rate of this reaction was investigated by ... show full transcript
Worked Solution & Example Answer:Hydrogen peroxide (H₂O₂) decomposes rapidly in the presence of a suitable catalyst to form water and a colourless gas - Leaving Cert Chemistry - Question 3 - 2014
Step 1
What is a catalyst?
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Answer
A catalyst is a substance that alters (speeds up or slows down) the rate of a chemical reaction without being consumed in the process. It helps to lower the activation energy required for the reaction to proceed.
Step 2
Suggest a suitable catalyst for the decomposition reaction.
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A suitable catalyst for the decomposition of hydrogen peroxide is manganese(IV) oxide (MnO₂). Other possible catalysts include potassium iodide (KI), liver, or celery.
Step 3
What gas was produced in the reaction?
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The gas produced in the reaction is oxygen (O₂).
Step 4
Draw a labelled diagram of a suitable apparatus for carrying out this experiment.
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A suitable apparatus diagram would typically include a conical flask containing hydrogen peroxide, a delivery tube connected to an inverted graduated gas collection syringe or water displacement setup, and the manganese(IV) oxide catalyst. The diagram should be clearly labelled with all components identified.
Step 5
Plot, on graph paper, a graph of volume (y-axis) versus time (x-axis).
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To plot the graph, mark the time points on the x-axis (0 to 3 minutes) and the volume of gas produced on the y-axis (0 to 30 cm³). Then plot the data points based on the provided table and connect them smoothly to visualize the trend.
Step 6
Estimate, from your graph, the volume of gas produced after 1.25 minutes.
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From the graph, the estimated volume of gas produced after 1.25 minutes is approximately 23 cm³.
Step 7
Does the rate of reaction increase or decrease with time? Give a reason for your answer.
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The rate of reaction decreases with time. This is because the concentration of the reactants (hydrogen peroxide) decreases as it is consumed in the reaction, leading to a decrease in the rate at which gas is produced.
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