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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
Increasing the temperature generally leads to an increase in the rate of reaction. This is because:
- Higher temperatures increase the average kinetic energy of reactant molecules.
- As a result, more molecules collide with sufficient energy to overcome the activation energy barrier.
- The frequency of successful collisions increases, thereby raising the rate of production of bromomethane.
Step 2
Step 3
Increasing pressure (constant temperature)
Answer
Increasing the pressure at constant temperature typically results in an increase in the rate of production of bromomethane, because:
- Increasing pressure effectively increases the concentration of gaseous reactants.
- This leads to a higher frequency of collisions between reactant molecules, thereby enhancing the rate of reaction.
Step 4
Reasoning
Answer
Under higher pressure, the molecules are forced closer together, facilitating more frequent collisions. In an equilibrium reaction, this favors the side of the reaction with fewer gas molecules, but for the current reaction, the increase in effective collisions boosts the rate at which bromomethane is produced.