The volume of oxygen liberated from liquid X in the presence of catalyst Y was measured at two-minute intervals using the apparatus shown in the diagram - Leaving Cert Chemistry - Question 8 - 2010
Question 8
The volume of oxygen liberated from liquid X in the presence of catalyst Y was measured at two-minute intervals using the apparatus shown in the diagram. The results... show full transcript
Worked Solution & Example Answer:The volume of oxygen liberated from liquid X in the presence of catalyst Y was measured at two-minute intervals using the apparatus shown in the diagram - Leaving Cert Chemistry - Question 8 - 2010
Step 1
Define catalyst.
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Answer
A catalyst is a substance that alters the rate of a chemical reaction but remains unchanged itself at the end of the reaction.
Step 2
Give (i) the name or formula of liquid X.
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The name of liquid X is Hydrogen peroxide or its formula is H₂O₂.
Step 3
Give (ii) the name or formula of catalyst Y.
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The name of catalyst Y is Manganese dioxide, which is represented by the formula MnO₂.
Step 4
When carrying out the experiment how would you decide that no further volume readings need to be taken?
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You would decide that no further volume readings need to be taken when no more gas is being produced, which is indicated by observing a plateau in the volume of gas collected.
Step 5
Plot, on graph paper, a graph of volume (y-axis) versus time (x-axis). From the graph estimate the volume of gas liberated after 3 minutes.
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When plotting the graph, the volume of gas liberated should be plotted against time, with the y-axis representing the volume (cm³) and the x-axis representing time (min). After plotting accurately, estimate the volume of gas liberated after 3 minutes, which appears to be around 34 cm³.
Step 6
Explain why the rate of the reaction decreases with time.
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The rate of the reaction decreases with time because the concentration of the reactants decreases as they are consumed, resulting in fewer successful collisions between reactant molecules.
Step 7
Using the same volume and concentration of liquid X and the same mass of catalyst Y as in the above experiment, suggest one way of increasing the rate of the reaction.
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One way to increase the rate of the reaction is to increase the temperature, which would provide the reactant molecules with more energy, leading to more frequent and successful collisions. Alternatively, using a more finely divided catalyst could also increase the rate.
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