10/11 - Equilibrium I & II
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What is meant by a state of dynamic equilibrium for a reversible reaction?
All reversible reactions reach a state of dynamic equilibrium. - A dynamic equilibrium occurs when the forwards and backwards reactions occur at equal rates continuously in a closed system. - The concentrations of reactants and products stay constant.
What is Le Chatelier’s Principle?
Le Chatelier’s Principle states that if an external condition is changed in a system at equilibrium, - The equilibrium will shift to oppose the change and try to reverse it.
How does a shift in the position of equilibrium affect the yield of product?
If the position of equilibrium shifts to the left, the yield of product decreases. - If the position of equilibrium shifts to the right, the yield of product increases.
What is the effect of a temperature increase on the position of equilibrium and yield of product for a forward exothermic reaction?
The equilibrium shifts to oppose the increase in temperature. - It moves in the backwards, endothermic direction to decrease the temperature. - The equilibrium shifts to the left. - The yield of product decreases.
What is the effect of a temperature increase on the position of equilibrium and yield of product for a forwards endothermic reaction?
The equilibrium shifts to oppose the increase in temperature. - It moves in the forward, endothermic direction to decrease the temperature. - The equilibrium shifts to the right. - The yield of the product increases.
What is the effect of a temperature decrease on the position of equilibrium and yield of product for a backward exothermic reaction?
The equilibrium shifts to oppose the decrease in temperature. - It moves in the backwards, exothermic direction to increase temperature. - The equilibrium shifts to the left. - The yield of product decreases.
What is the effect of a temperature decrease on the position of equilibrium and yield of product for a forwards exothermic reaction?
The equilibrium shifts to oppose the decrease in temperature. - It moves in the forwards, exothermic direction to increase temperature. - The equilibrium shifts to the right. - The yield of product increases.
Why is a suitable temperature in industrial reactions not always the ideal temperature for a maximum yield?
A low temperature may increase yield but decrease the rate of reaction. • A high temperature may increase the rate of reaction but decrease the yield. • A compromise temperature is used that produces a reasonable rate and yield.
What is the effect of an increase in pressure on the position of equilibrium and yield of product for a reaction where the backwards direction produces fewer gaseous moles?
The equilibrium shifts to oppose the increase in pressure. • It moves towards the direction with fewer moles of gas to reduce the pressure. • The equilibrium shifts to the left. • The yield of product decreases.
What is the effect of an increase in pressure on the position of equilibrium and yield of product for a reaction where the forward direction produces fewer gaseous moles?
The equilibrium shifts to oppose the increase in pressure. - It moves towards the direction with fewer moles of gas to reduce the pressure. - The equilibrium shifts to the right. - The yield of product increases.
What is the effect of a decrease in pressure on the position of equilibrium and yield of product where the backwards direction produces more gaseous moles?
The equilibrium shifts to oppose the decrease in pressure. - It moves towards the direction with more moles of gas to increase the pressure. - The equilibrium shifts to the left. - The yield of product decreases.
What is the effect of a decrease in pressure on the position of equilibrium and yield of product where the forward direction produces more gaseous moles?
The equilibrium shifts to oppose the decrease in pressure. - It moves towards the direction with more moles of gas to increase the pressure. - The equilibrium shifts to the right. - The yield of product increases.
Why is a suitable pressure in industrial reactions not always the ideal pressure for a maximum yield/rate?
A higher pressure may increase yield and rate of reaction. - However, high pressures are expensive to produce. - This is due to high energy costs for pumps to produce high pressures. - There are higher costs for equipment that can withstand high pressures. - A compromise pressure is used that considers maximum yield/rate and expense.
What is the effect of an increase in reactant concentration on the position of equilibrium and yield of product?
The equilibrium shifts to oppose the increase in concentration. - The equilibrium shifts to the right to remove the reactant. - The yield of product increases.
What is the effect of an increase in product concentration on the position of equilibrium and yield of product?
The equilibrium shifts to oppose the increase in concentration. - The equilibrium shifts to the left to remove the product. - The yield of the reactant increases.
What is the effect of a decrease in reactant concentration on the position of equilibrium and yield of product?
The equilibrium shifts to oppose the decrease in concentration. - The equilibrium shifts to the left to increase the reactant concentration. - The yield of products decreases.
What is the effect of a decrease in product concentration on the position of equilibrium and yield of product?
The equilibrium shifts to oppose the decrease in concentration. - The equilibrium shifts to the right to increase the product concentration. - The yield of the reactants decreases.
How does a catalyst affect the position of equilibrium?
A catalyst does not affect the position of equilibrium. - This is because it increases the rate of reaction equally in both directions.
What is the effect of a catalyst on the rate at which equilibrium is reached?
The catalyst speeds up the rate at which equilibrium is achieved.
What is the equilibrium constant Kc?
Kc indicates the position of equilibrium for a reaction at a certain temperature.
What does the relative value of Kc tell you about the position of equilibrium?
If Kc«1, then the position of equilibrium favours the reactants. - If Kc»1, then the position of equilibrium favours the products. - If Kc H 1, then the concentrations of products and reactants are approximately equal.
What is the formula to calculate Kc and its units?
Kc is calculated using the concentrations of aqueous/gaseous reactants and products at equilibrium. - The units are calculated by substituting the units into the Kc expression.
What is a homogenous system and a heterogenous system?
A homogenous system is a system where all substances are in the same state. - A homogenous system is a system where not all substances are in the same state.
How is the calculation of Kc is different for a homogenous and heterogenous reaction?
In a homogeneous reaction, the concentrations of all substances are included in the calculation of Kc. - In a heterogeneous reaction, solids and pure liquids are omitted and only aqueous solutions and gases are included in the calculation of Kc.