Question

q2. manganese dioxide catalyses the decomposition of hydrogen peroxide solution. oxygen and water are produced. (a) explain how a manganese dioxide catalyst increases the rate of decomposition of hydrogen peroxide. (e) fine manganese dioxide powder produces a higher rate of reaction than coarse manganese dioxide lumps. sketch on the figure above the results you would expect for student bs experiment with fine manganese dioxide powder. hydrogen peroxide molecules collide with manganese dioxide particles during the reaction. (f) why does fine manganese dioxide powder produce a higher rate of reaction than coarse manganese dioxide lumps? tick (✓) one box. fine manganese dioxide powder has a larger surface area. fine manganese dioxide powder has larger particles. fine manganese dioxide powder produces less frequent collisions. (total 10 marks)

Explanation:

Step1: Explain catalyst action

A catalyst like manganese - dioxide provides an alternative reaction pathway with a lower activation energy for the decomposition of hydrogen peroxide. This allows more hydrogen - peroxide molecules to have sufficient energy to react, thus increasing the rate of decomposition.

Step2: Answer multiple - choice

Fine manganese dioxide powder has a larger surface area. A larger surface area means more sites for the reactant (hydrogen - peroxide) molecules to collide with the catalyst, increasing the frequency of effective collisions and the reaction rate. So the correct box to tick is "Fine manganese dioxide powder has a larger surface area."

Step3: Explain reaction rate difference

Fine manganese dioxide powder has a larger surface area compared to coarse manganese dioxide lumps. More surface area provides more contact points for hydrogen - peroxide molecules, leading to a higher rate of reaction as there are more frequent collisions between reactant and catalyst.

Step4: Sketch explanation

The sketch would likely show a steeper curve for the reaction with fine manganese dioxide powder compared to coarse lumps, indicating a faster production of oxygen (since the rate of decomposition is higher), with time on the x - axis and volume of oxygen produced on the y - axis.

Answer:

(a) A catalyst (manganese dioxide) provides an alternative reaction pathway with lower activation energy, increasing the fraction of hydrogen - peroxide molecules with sufficient energy to react, thus increasing the decomposition rate.
(b) Tick the box: Fine manganese dioxide powder has a larger surface area.
(c) Fine manganese dioxide powder has a larger surface area, providing more sites for hydrogen - peroxide molecules to collide with the catalyst, resulting in a higher reaction rate than coarse lumps.
(d) Sketch: A graph with time on the x - axis and volume of oxygen produced on the y - axis, with a steeper curve for the reaction with fine manganese dioxide powder compared to coarse lumps.