Fig. 1 represents particles in two sealed reaction vessels used to make a harmless chloride compound from a toxic gas. Vessel A has a lower temperature than...
Question 1 Report
Fig. 1 represents particles in two sealed reaction vessels used to make a harmless chloride compound from a toxic gas. Vessel A has a lower temperature than vessel B. The same number of particles is present in each vessel. The diagram includes arrows of different lengths to show particle speeds. A reaction occurs only when particles collide with enough energy and in a suitable arrangement.
(a) Name the vessel with the higher temperature. Use evidence from Fig. 1. [3]
(b) Describe what is meant by activation energy. [3]
(c) Explain why vessel B has a faster reaction rate. [4]
(d) Use the diagram to explain why increasing pressure would increase rate for gaseous reactants but would have little effect on a reaction between solids. [4]
Answer Details
(a) Vessel B has the higher temperature. Its particles have longer arrows, showing greater speed; faster particles have greater kinetic energy. [3]
(b) Activation energy is the minimum energy that reacting particles need during a collision in order to react. This energy is needed to break bonds or start the reaction. [3]
(c) In vessel B, particles move faster, so collisions occur more frequently. Also, a greater fraction of collisions have energy equal to or greater than the activation energy. There are therefore more successful collisions per second, giving a faster rate. [4]
(d) Increasing pressure pushes gas particles closer together. They collide more often, so the gas reaction rate rises. In a solid, particles are already fixed very close together, so pressure has little effect on their collision frequency or exposed surface area. [4]
Download The App On Google Playstore
Everything you need to excel in your exams
