5.1 Define reaction rate.
5.2 INVESTIGATION I
The results obtained in INVESTIGATION I are shown in the graph below.
For this investigation, write down the:
5.2.1 ... show full transcript
Worked Solution & Example Answer:5.1 Define reaction rate - NSC Physical Sciences - Question 5 - 2019 - Paper 2
Step 1
Define reaction rate.
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Answer
The reaction rate is defined as the change in concentration of reactants or products per unit time. It indicates how quickly the reactants are converted into products during a chemical reaction.
Step 2
5.2.1 Dependent variable
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Answer
The dependent variable in this investigation is the reaction rate, which is measured against the concentration of Na₂S₂O₃(aq).
Step 3
5.2.2 Conclusion that can be drawn from the results.
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From the graph, it can be concluded that the reaction rate increases with an increase in the concentration of Na₂S₂O₃(aq). This implies a direct relationship between concentration and reaction rate, indicating that higher concentrations lead to more frequent particle collisions.
Step 4
5.3.1 What does line P represent?
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Answer
Line P represents the activation energy required for the molecules to collide and form effective products. It signifies the minimum energy that particles must possess to undergo a successful reaction.
Step 5
5.3.2 Which curve (A or B) was obtained at the higher temperature?
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Curve B was obtained at the higher temperature. This curve shows a greater number of particles with higher kinetic energy, indicating an increase in temperature.
Step 6
5.3.3 Explain, in terms of the collision theory, how an increase in temperature influences the rate of a reaction.
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Answer
According to collision theory, an increase in temperature results in particles moving faster and possessing more kinetic energy. This leads to an increased frequency of collisions and a greater proportion of those collisions having sufficient energy to overcome the activation energy barrier, thereby increasing the reaction rate.
Step 7
5.4 Give a reason why curve Y differs from curve X.
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Curve Y differs from curve X because it represents the reaction in the presence of a catalyst, which lowers the activation energy. This results in a higher reaction rate as more particles can achieve the energy needed to react.
Step 8
5.5 Calculate the PERCENTAGE YIELD of sulphur.
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Answer
The percentage yield of sulphur can be calculated using the formula:
First, calculate the theoretical yield:
The balanced equation indicates that 2 moles of Na₂S₂O₃ produce 1 mole of S.
Molar mass of S = 32 g/mol.
Moles of S produced = 0.18 g / 32 g/mol = 0.005625 mol.
According to the reaction, this corresponds to 0.005625 * 2 = 0.01125 mol of Na₂S₂O₃.
Calculate the mass of Na₂S₂O₃ needed:
Molar mass of Na₂S₂O₃ = 158 g/mol:
Theoretical mass of Na₂S₂O₃ = 0.01125 mol * 158 g/mol = 1.77 g.
