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Zinc is a metal - Edexcel - GCSE Chemistry - Question 2 - 2013 - Paper 1
Question 2
Zinc is a metal. Zinc reacts with dilute hydrochloric acid to produce zinc chloride and hydrogen. Edward used this apparatus to investigate the speed of the reaction... show full transcript
Worked Solution & Example Answer:Zinc is a metal - Edexcel - GCSE Chemistry - Question 2 - 2013 - Paper 1
Step 1
Sketch a line on the graph to show the results that Edward should expect to obtain if he carried out the experiment to completion at 30 °C.
Answer
To sketch the expected results for the experiment at 30 °C, draw a curve that originates at the same starting point as the 50 °C curve but has a lower gradient to indicate a slower reaction rate. The curve should rise initially, but then level off at the same volume of gas as the 50 °C experiment once the reaction is completed, reflecting that the total amount of hydrogen produced would be the same, albeit at a slower rate.
Step 2
An explanation linking the following: (i) zinc powder has a larger surface area
Answer
Zinc powder has a larger surface area compared to larger pieces of zinc, which means that when it is in contact with dilute hydrochloric acid, there are more particles available for reaction. This results in an increased frequency of successful collisions between zinc particles and acid particles.
Step 3
An explanation linking the following: (ii) breaking bonds requires heat/energy
Answer
Breaking bonds in chemical reactions is an endothermic process that requires energy input. Similarly, forming new bonds releases energy, categorizing it as an exothermic process. In summary, the overall energy change in a reaction depends on the balance between these two processes, leading to either energy absorption or release.
Step 4
What effect does a catalyst have on a reaction?
Answer
A catalyst increases the reaction rate by providing an alternative pathway with a lower activation energy required for the reaction to proceed. This means that more reactant particles can collide with sufficient energy to overcome the activation barrier, thus speeding up the rate of reaction.