Photo AI
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 reacti... 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 line representing the reaction at 30 °C, we should start at the origin of the graph. The line should initially rise slowly, indicating a lower reaction rate compared to the reaction at 50 °C. As the reaction proceeds, the line should increase in volume of gas but at a lower gradient than that of the curve at 50 °C. Finally, the line should flatten out as it approaches the same volume as seen in the 50 °C curve, indicating that the reaction has gone to completion. This indicates that while the overall volume of gas produced is the same, the rate of production is slower at the lower temperature.
Step 2
Explain why zinc powder has a larger surface area than pieces of zinc.
Answer
Zinc powder consists of smaller particles, which significantly increases the surface area compared to larger pieces of zinc. A larger surface area allows for more particles to be in contact with the acid at any given time, leading to a greater number of successful collisions between the zinc and the hydrochloric acid molecules. Consequently, this results in a faster reaction rate.
Step 3
Explain the energy changes involved in breaking and forming bonds.
Answer
Breaking bonds requires energy as it is an endothermic process; thus, heat energy is taken in during this step. Conversely, forming bonds releases energy and is an exothermic process, which means that more heat energy is given out than is taken in overall during the reaction. This interplay of energy changes explains the behavior of the reaction in terms of energy absorption and release.
Step 4
Describe how temperature affects the rate of reaction.
Answer
Increasing the temperature generally makes the reaction go faster. This is due to the increase in kinetic energy of the particles involved, which causes them to move more rapidly and collide more frequently with sufficient energy to overcome the activation energy barrier, hence increasing the rate of reaction.