equlibria

• What does the term "reversible reactions" refer to in the context of equilibria?

  Reactions that can proceed in both forward and backward directions
• How is the forward and backward reaction represented in equilibria?

  With arrows that resemble harpoons
• What happens to the concentration of reactants over time in a reversible reaction?

  The concentration of reactants decreases as they are used up
• What is meant by "dynamic equilibrium"?

  It is when the rate of the forward reaction equals the rate of the backward reaction
• What is the key difference between concentration and the amount of reactants and products?

  Concentration refers to the amount of substance per unit volume, while amount refers to the total quantity
• In what type of systems does equilibrium occur?

  In closed systems
• What does Le Chatelier's principle state?

  If a reaction at equilibrium is subjected to a change in pressure, temperature, or concentration, the equilibrium will shift to counteract that change
• What happens to equilibrium if the concentration of a reactant is increased?

  The equilibrium will shift to the right to reduce the concentration of that reactant
• If the concentration of ammonia is increased, what will happen to the equilibrium?

  The equilibrium will shift to the left to use up the excess ammonia
• How does an increase in pressure affect equilibrium?

  The equilibrium will shift to the side with fewer gas particles
• What is the effect of increasing temperature on an exothermic reaction at equilibrium?

  The equilibrium will shift to the left in the endothermic direction
• What is the role of catalysts in equilibrium reactions?


  Catalysts speed up both the forward and backward reactions but do not affect the position of equilibrium
• What is the reaction for producing ethanol from ethene and water?

  Ethene reacts with water to form ethanol
• What is the compromise temperature used in the production of ethanol?

  300 degrees Celsius
• Why is a high pressure used in the production of ethanol?

  To shift the equilibrium to the right and produce more ethanol
• What is the equilibrium constant (Kc)?

  Kc is a value that represents the ratio of the concentrations of products to reactants at equilibrium
• What is the Kc expression for the reaction SO2 + O2 ⇌ 2SO3?

  Kc = [SO3]^2 / [SO2][O2]
• What must concentrations be in when calculating Kc?

  Concentrations must be in molar concentration (mol/dm³)
• What is the significance of the molar values in the Kc expression?

  The molar values become the powers in the Kc expression
• How do you calculate the value of Kc for a reaction?

  By substituting the concentrations of the reactants and products into the Kc expression
• What is the importance of understanding Kc in equilibria?

  It helps predict the behavior of the reaction at equilibrium
• How does changing the concentration of reactants affect the equilibrium position?

  Increasing reactant concentration shifts equilibrium to the right, while decreasing it shifts equilibrium to the left
• How does changing pressure affect the equilibrium position in a reaction with gas particles?

  Increasing pressure shifts equilibrium to the side with fewer gas particles, while decreasing pressure shifts it to the side with more gas particles
• How does changing temperature affect the equilibrium position in an exothermic reaction?

  Increasing temperature shifts equilibrium to the left (endothermic direction), while decreasing it shifts to the right (exothermic direction)
• What is the relationship between catalysts and equilibrium?

  Catalysts speed up the rate at which equilibrium is established but do not change the position of equilibrium
• What is the compromise in conditions for producing ethanol?

  The compromise is between yield, rate of reaction, and cost
• Why is it important to understand Kc in the context of equilibria?

  Understanding Kc allows for predictions about the concentrations of reactants and products at equilibrium
• How does the equilibrium constant (Kc) relate to the concentrations of reactants and products?

  Kc is calculated from the concentrations of products divided by the concentrations of reactants, raised to the power of their coefficients
• What must be true about the concentrations used in the Kc expression?

  They must be in molar concentration (mol/dm³)
• How do you calculate Kc for a reaction with given concentrations?

  By substituting the concentrations into the Kc expression
• What do square brackets indicate in a KC expression?

  Square brackets indicate concentration.
• Why must concentrations be used instead of moles in a KC expression?

  Because KC expressions require concentrations to be accurate.
• How do you determine the units of \(K_C\)?

  By analyzing the concentration units in the expression.
• What happens to the units of \(K_C\) when you calculate them from the expression?

  The units can be inverted based on the concentration terms.
• What is the acronym used to organize the information for calculating equilibrium concentrations?

  ICE (Initial, Change, Equilibrium).
• How do you calculate the number of moles of \(\text{NO}_2\) from its mass?

  By using the formula: moles = mass / molar mass.
• How do you calculate the equilibrium concentration of a species?

  By dividing the number of moles by the volume of the reaction vessel.
• How does an increase in temperature affect an exothermic reaction's \(K_C\)?

  It decreases \(K_C\) as the equilibrium shifts to the left.
• What happens to \(K_C\) if the concentration of products increases?

  \(K_C\) will increase.
• How does a catalyst affect the value of \(K_C\)?

  A catalyst does not affect the value of \(K_C\).