온도 의존성
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Q1: Why is iron (III) nitrate used as a catalyst in the hydrogen peroxide decomposition experiment?
Iron (III) nitrate lowers the activation energy of the decomposition reaction, allowing hydrogen peroxide to break down into water and oxygen much faster than it would naturally. The iron undergoes a redox reaction during the process and returns to its original oxidation state, which you can observe as a color change in the solution.
Q2: How does temperature affect the rate of hydrogen peroxide decomposition?
Higher temperatures increase the reaction rate, producing oxygen gas more quickly. By performing the decomposition at four different temperatures and measuring pressure changes, you can quantify this relationship and calculate the apparent activation energy using the Arrhenius equation to determine how temperature influences reaction kinetics.
Q3: What does the pressure change inside the flask indicate during the experiment?
The pressure increase is directly proportional to the rate of oxygen production from hydrogen peroxide decomposition. By recording pressure changes over time using a gas pressure sensor, you can determine the reaction rate at each temperature and track how quickly the decomposition occurs.
Q4: How do you calculate apparent activation energy from experimental data?
Plot the natural log of the pressure change rate against the reciprocal of absolute temperature to create an Arrhenius plot. The slope of this line equals negative activation energy divided by the universal gas constant. Multiply the slope by the negative gas constant to obtain the apparent activation energy value.
Q5: Why is it important to evacuate the flask to 10 kPa before each trial?
Evacuating the flask removes air and creates a sealed system where pressure changes accurately reflect only the oxygen produced from the reaction. This ensures that your pressure measurements are reliable and not affected by atmospheric air or leaks in the apparatus.
Q6: What is the expected range for the apparent activation energy of the catalyzed decomposition?
The iron-catalyzed decomposition of hydrogen peroxide yields an apparent activation energy between 35 and 60 kJ/mol, significantly lower than the uncatalyzed reaction at 78–88 kJ/mol. This difference demonstrates how effectively the iron catalyst reduces the energy barrier for the reaction.