An arrangement of apparatus similar to that shown below was used to investigate the rate of decomposition of a hydrogen peroxide (H₂O₂) solution, in the presence of a solid catalyst, releasing oxygen gas - Leaving Cert Chemistry - Question 3 - 2020

The appearance of manganese(IV) oxide is typically a black or dark brown powder. It may also present as small particles or grains, resembling powdery substances.

The chemical hazard indicated by the pictogram is that the substance is an oxidizing agent. This suggests that it can cause or enhance the combustion of other materials.

One important safety precaution is to always wear appropriate personal protective equipment (PPE), such as gloves and goggles, to prevent skin and eye contact with hydrogen peroxide solutions.

To start the reaction simultaneously with the timer, the catalyst should be added to the hydrogen peroxide solution just as the timer is activated. This requires careful timing and possibly a setup where both components can be mixed instantly.

The graph should have volume of O₂ in cm³ on the y-axis and time in minutes on the x-axis. Points should be plotted based on the data collected at each minute, with a smooth curve drawn through the points to represent the overall trend in oxygen production.

From the table, at 2 minutes the volume of oxygen produced was 35 cm³ and at 3 minutes it was 61 cm³. To find the volume at 2.5 minutes, we can interpolate between these two values. This gives an approximate volume of around 48 cm³.

The difference in the results for the volumes of oxygen produced can be attributed to the change in the concentration of hydrogen peroxide over time. As the reaction progresses, the concentration of H₂O₂ decreases, leading to a slower rate of reaction due to fewer reactant molecules being available for collision, ultimately resulting in a reduced rate of oxygen gas production.