Photo AI
The student investigated the rate by using different sizes of marble chips - Edexcel - GCSE Chemistry Combined Science - Question 8 - 2016 - Paper 1
Question 8
The student investigated the rate by using different sizes of marble chips. In their investigation, the same mass of marble chips was used in each experiment. The vo... show full transcript
Worked Solution & Example Answer:The student investigated the rate by using different sizes of marble chips - Edexcel - GCSE Chemistry Combined Science - Question 8 - 2016 - Paper 1
Step 1
State how the graph shows that line B gives the results for the larger size of marble chips.
Answer
Line B on the graph indicates a higher volume of gas produced over the same time period compared to line A. This suggests that the larger marble chips when reacted, produce gas at a faster rate. The steeper slope of line B compared to line A illustrates that the reaction occurs more quickly with the larger chips, evidencing a correlation between size and reaction rate due to the increased surface area allowing more frequent collisions between reactants.
Step 2
Explain, in terms of particles, why the rate of reaction decreases.
Answer
As the reaction proceeds, the concentration of reactants decreases, leading to fewer particles available for collisions. In terms of particle theory, when there are fewer reactant particles in a given volume, the chances of successful collisions between them diminish, resulting in a slower reaction rate. This decrease in concentration over time reduces the frequency of effective collisions, thus slowing the overall rate of the reaction.
Step 3
Which of these graphs shows the mass of the catalyst as the reaction takes place?
Answer
Graph A shows the mass of the catalyst remaining constant over time, which is typical for a catalyst as it is not consumed in the reaction. Graph B, conversely, suggests a decrease in mass, which is not characteristic of a catalyst. Therefore, graph A accurately represents the mass of the catalyst as the reaction proceeds.