All of these questions can be answered easily by understanding Le Chatelier's Principle and the factors affecting rate of reaction.
There are two main factors which are taken into account when creating the conditions for a chemical reaction: the equilibrium yield of the reaction and the rate of the reaction.
The yield of a reaction is affected by the temperature and pressure of the environment. According to Le Chateliers Principle, if a change in temperature or pressure is applied to a reaction system, the equilibrium of the reaction will shift as to oppose the change that caused it.
For example, in the first question we are given this endothermic reaction:
N2O4 --> 2NO2
The reaction is endothermic so we know that for part b, the equilibrium will shift to the right. This is because the temperature is increased, and to oppose this the endothermic forward reaction occurs at a greater rate than the reverse reaction, to "absorb the extra heat." Since NO2 is produced more than N2O4, the gas will turn brown.
For part C, we are given that the pressure increases. An increase in pressure will always favour the side with fewer molecules, to keep the total number of molecules constant, and vice versa. If the total number of molecules is the same on both sides, pressure changes will have no effect on the equilibrium. Since the right hand side of the equation has 2 NO2 molecules, and the left side only one N2O4 molecule, increasing the pressure will shift the equilibrium to the left so that more N2O4 is produced. This causes the gas to turn pale yellow.
The rate of a reaction is affected by the temperature, concentration and surface area of the reactants.
Increasing the temperature will always increase the rate of reaction, as particles are moving faster, and so reactants are more likely to collide and react with each other.
Increasing concentration will also increase the rate of reaction up to a certain point, as there will be more reactant particles in a given volume, so more collisions occur.
Increasing the surface area of solid reactants increases the rate of reaction, as there are more physical sites at which reactions can occur. For example, for question 1 on the rates section, reactions with the magnesium powder will have a much higher rate of reaction compared to those with a magnesium lump as powders have much higher surface areas.
I hope this helps! Please let me know if you have any further questions.
Hi @EM,
All of these questions can be answered easily by understanding Le Chatelier's Principle and the factors affecting rate of reaction.
There are two main factors which are taken into account when creating the conditions for a chemical reaction: the equilibrium yield of the reaction and the rate of the reaction.
The yield of a reaction is affected by the temperature and pressure of the environment. According to Le Chateliers Principle, if a change in temperature or pressure is applied to a reaction system, the equilibrium of the reaction will shift as to oppose the change that caused it.
For example, in the first question we are given this endothermic reaction:
N2O4 --> 2NO2
The reaction is endothermic so we know that for part b, the equilibrium will shift to the right. This is because the temperature is increased, and to oppose this the endothermic forward reaction occurs at a greater rate than the reverse reaction, to "absorb the extra heat." Since NO2 is produced more than N2O4, the gas will turn brown.
For part C, we are given that the pressure increases. An increase in pressure will always favour the side with fewer molecules, to keep the total number of molecules constant, and vice versa. If the total number of molecules is the same on both sides, pressure changes will have no effect on the equilibrium. Since the right hand side of the equation has 2 NO2 molecules, and the left side only one N2O4 molecule, increasing the pressure will shift the equilibrium to the left so that more N2O4 is produced. This causes the gas to turn pale yellow.
The rate of a reaction is affected by the temperature, concentration and surface area of the reactants.
Increasing the temperature will always increase the rate of reaction, as particles are moving faster, and so reactants are more likely to collide and react with each other.
Increasing concentration will also increase the rate of reaction up to a certain point, as there will be more reactant particles in a given volume, so more collisions occur.
Increasing the surface area of solid reactants increases the rate of reaction, as there are more physical sites at which reactions can occur. For example, for question 1 on the rates section, reactions with the magnesium powder will have a much higher rate of reaction compared to those with a magnesium lump as powders have much higher surface areas.
I hope this helps! Please let me know if you have any further questions.
I perhaps wanted a step by step explanation for each or a worked example - if that's possible?
It was a booklet I received and I managed to do the rest but its just these few questions I am struggling with.
The explanations I have received in the past forums have really helped and have enabled me to answer questions I found tricky before !
I hope you can understand.
Hey @EM,
What are we looking at specifically?
Thanks,
Joel :)