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Bromomethane, CH3Br, is a toxic, odourless and colourless gas - VCE - SSCE Chemistry - Question 5 - 2016 - Paper 1
Question 5
Bromomethane, CH3Br, is a toxic, odourless and colourless gas. It is used by quarantine authorities to kill insect pests. A simplified reaction for its synthesis is ... show full transcript
Worked Solution & Example Answer:Bromomethane, CH3Br, is a toxic, odourless and colourless gas - VCE - SSCE Chemistry - Question 5 - 2016 - Paper 1
Step 1
Increasing temperature (constant volume)
Answer
Answer
Increasing the temperature at constant volume will primarily affect the kinetic energy of the reactant molecules. As temperature increases, the average kinetic energy of the molecules increases, leading to more frequent and energetic collisions between the reactants. It can be predicted that:
- Prediction: Increase
Reasoning
The increase in temperature causes more molecules to possess energy greater than the activation energy, thereby increasing the proportion of successful collisions. This results in an increased rate of production of bromomethane.
Step 2
Increasing pressure (constant temperature)
Answer
Answer
Increasing the pressure at constant temperature will alter the concentration of the gaseous reactants involved in the reaction. Predictably, this leads to:
- Prediction: Increase
Reasoning
Increasing pressure effectively increases the concentration of the gaseous reactants. According to Le Chatelier's Principle, raising the pressure will shift the equilibrium towards the side with fewer moles of gas. Since the overall reaction produces one mole of bromomethane and one mole of water (2 moles in total), the shift in equilibrium will favor the production of bromomethane (CH3Br), thus increasing its rate of production.