QUESTION 5 The graph below shows the energy changes duri…
QUESTION 5 The graph below shows the energy changes during the course of a chemical reaction. Right click on the following blue button to open ALL THE IMAGES for QUESTION 5, in a new tab. 5.1 Define ‘activation energy’. (2) 5.2 Does the graph represent an endothermic or exothermic reaction? Motivate your answer. (2) 5.3 Write down the activation energy for the reverse reaction in kJ.mol-1 (2) 5.4 A suitable catalyst was obtained for this reaction. Redraw the given graph and clearly indicate what the effect of the catalyst will be on the activation energy. (2) 5.5 How will the addition of a catalyst affect the ΔH? (2) 5.6 The following curves suggest different factors that can influence the rate of a chemical reaction. Please refer to Diagram 2, Question 5 to answer the following questions. 5.6.1 Which line X, Y or Z, represents an increase in the concentration of the reactants? (2) 5.6.2 Use the collision theory to explain how the increase in concentration will affect the reaction rate. (3) 5.7 A study was done to find out the effect of the concentration of a reactant on the total time it takes to complete a chemical reaction. Four attempts of the same reaction are performed. In each attempt, the initial concentration of the reactant was different. The time required to complete the reaction is measured each time. The data for each of the four attempts are shown in the table below. Please refer to Diagram 3, Question 5 to answer the following questions. 5.7.1 Provide an investigative question for this experiment. (2) 5.7.2 Identify the dependent variable. (1) 5.7.3 Use the results in the table and draw a graph. (4) 5.7.4 Use your graph and calculate the average reaction rate for the first 40 s. (4) 5.7.5 Write a conclusion for this experiment. (2)