Equilibria

• What is the equilibrium constant denoted as?

  KC
• Why is KC considered a bit weird?

  It ties into new specifications and legacy exams
• What is the general form of an equilibrium reaction mentioned?

  A + 2B ⇌ C + 3D
• What do square brackets represent in equilibrium expressions?

  Concentration in moles per decimeter cubed
• How is the equilibrium constant expression for KC written?

  Products over reactants with indices
• What happens to the value of KC when concentrations change?

  It remains constant; only temperature affects it
• What is the only factor that changes the value of KC?

  Temperature
• What units are used for KC?

  Moles per decimeter cubed
• How do you calculate the units for KC?

  By analyzing the concentrations of products and reactants
• What is the significance of the molar ratio in KC calculations?

  It determines the indices in the equilibrium expression
• What topic does this video cover from the AQA AS chemistry specification?

  Equilibria
• What is the relationship between moles of A and C in the reaction A + B ⇌ 3C?

  1 mole of A produces 3 moles of C
• Why do students often find the equilibria topic challenging?

  It has specific answers AQA expects
• What does the reversible reaction sign indicate in an equilibrium reaction?

  The reaction can proceed in both directions
• If 1 mole of A produces 3 moles of C, how many moles of A are needed for 1.2 moles of C?

  0.4 moles of A
• What is required for a system to be in equilibrium?

  It must be in a closed system
• How do you find the moles of B if 0.4 moles of A reacted?

  1.1 moles of B remain
• What is the equilibrium expression for the reaction producing methanol?

  KC = [CH3OH]/([CO][H2]^2)
• How do you calculate the concentrations for KC?

  Divide moles by the volume of the container
• What are two key properties of a reaction at equilibrium?

  Rates of forward and backward reactions are equal
• What happens to KC if more hydrogen is added to the equilibrium mixture?

  No effect; only temperature changes KC
• Why is the term "rate" important when discussing equilibrium?

  It indicates the occurrence of reactions
• What is the significance of the enthalpy change in the reaction?

  It indicates the heat absorbed or released
• What does Le Chatelier's principle state?

  Equilibrium shifts to oppose a change
• What is the equilibrium concentration of methanol at equilibrium?

  0.070 moles
• How do you find the equilibrium moles of hydrogen after the reaction?

  0.240 moles of hydrogen remain
• What is the final value of KC for the reaction at the given temperature?

  11.6 to 11.7
• What is the effect of temperature on the equilibrium constant?

  Only temperature changes the value of KC
• What happens when a factor is changed in an equilibrium?

  The equilibrium shifts to oppose that change
• What types of changes can affect equilibrium?

  Temperature and pressure changes
• How does decreasing temperature affect the yield of methanol in the reaction?

  It increases the yield of methanol
• What is the enthalpy change for the forward reaction producing methanol?

  -49 kJ per mole, indicating exothermic
• What does it mean if the forward reaction is exothermic?

  Energy is released during the reaction
• How does the equilibrium shift when the temperature is decreased?

  It shifts towards the exothermic direction
• What is the effect of increasing pressure on equilibrium?

  It can shift the equilibrium position
• What are the key concepts of equilibrium in chemistry?

  • Dynamic equilibrium: forward and backward reactions occur simultaneously
  • Rates of reactions are equal at equilibrium
  • Concentrations of reactants and products remain constant
• How can the yield of methanol be increased in its formation reaction?

  • Decrease temperature to favor exothermic reaction
  • Increase pressure if there are fewer moles of gas on products side
• What are the implications of Le Chatelier's principle in chemical reactions?

  • Equilibrium shifts to counteract changes
  • Adjustments can lead to different equilibrium positions
  • Important for optimizing yields in industrial processes
• What happens to the equilibrium when temperature decreases?

  It shifts right to favor exothermic reaction
• Why does yield increase when temperature decreases?

  Because the forward reaction is exothermic