5.1.2

• What is a catalyst?

  A substance that speeds up reactions
• What does concentration refer to in a solution?

  Amount of substance per unit volume
• What characterizes an endothermic reaction?

  It takes in energy from the surroundings
• How does the energy of products compare to reactants in an endothermic reaction?

  Products have higher energy than reactants
• What does equilibrium mean in a chemical reaction?

  Forward and reverse reactions occur at the same rate
• What is the equilibrium constant (K)?

  A value relating products and reactants at equilibrium
• What factors affect the equilibrium constant (K)?

  K is affected by temperature only
• What is an exothermic reaction?

  A reaction that gives out energy to surroundings
• How does the energy of reactants compare to products in an exothermic reaction?

  Reactants have higher energy than products
• What defines heterogeneous equilibrium?

  Involves substances in different states
• What defines homogeneous equilibrium?

  Involves substances all in the same state
• How is the equilibrium constant (K) calculated?

  K = products' concentrations / reactants' concentrations
• What is excluded from heterogeneous K expressions?

  Liquids and solids are excluded
• Why are liquids and solids excluded from K expressions?

  Their concentrations remain constant
• What does K_p represent in chemistry?

  The equilibrium constant for gas reactions
• How is K_p calculated?

  Products' partial pressures over reactants' partial pressures
• What is the formula for mole fraction X_A?

  X_A = n_A/n
• What does n_A represent in the mole fraction formula?

  The number of moles of component A
• What is the definition of partial pressure?

  Pressure exerted by one gas in a mixture
• How is the partial pressure P_A calculated?

  P_A = P X_A
• What does P represent in the partial pressure formula?

  The total pressure of the gas mixture
• What does X_A signify in the context of partial pressure?

  The mole fraction of gas A in the mixture