Reversible reactions Knowledge-Based Download PDF

Questions

1. 1.

   Which experimental condition prevents a reversible gas-phase reaction from establishing a state of dynamic chemical equilibrium?

   • A) Initiating the reaction with unequal stoichiometric amounts of reactants
   • B) Maintaining the reaction mixture at a relatively low, constant temperature
   • C) Operating the reaction in an open container where gaseous species can freely escape
   • D) Adding a solid catalyst that increases the rate of both forward and reverse pathways
2. 2.

   A sealed reaction flask is charged solely with the gaseous product of a reversible chemical reaction at a constant temperature. Which outcome will be observed as the system reaches chemical equilibrium?

   • A) The product remains entirely unreacted because reversible reactions can only initiate in the forward direction.
   • B) A portion of the product converts into reactants until constant concentrations of both reactants and products are maintained.
   • C) The product converts completely into reactants because the reverse process cannot attain an equilibrium state.
   • D) The rate of reactant formation continuously accelerates until all product molecules are consumed.
3. 3.

   When pure reactants are initially mixed in a closed container at a constant temperature, how do the rates of the forward and reverse reactions change as the system approaches dynamic equilibrium?

   • A) Both the forward and reverse reaction rates increase steadily over time.
   • B) The forward reaction rate remains constant while the reverse reaction rate increases from zero.
   • C) The forward reaction rate decreases while the reverse reaction rate increases from zero.
   • D) The forward reaction rate decreases to zero while the reverse reaction rate increases to its maximum.
4. 4.

   Why is a reversible chemical reaction conducted in a closed vessel unable to achieve complete conversion of reactants into products?

   • A) The products can interact to regenerate the original reactants simultaneously.
   • B) The forward reaction permanently stops once any product molecules are formed.
   • C) The activation energy of the forward pathway increases to infinity as time passes.
   • D) Matter is steadily lost to the surroundings through chemical destruction.
5. 5.

   Which statement correctly describes a reversible chemical reaction that has reached dynamic equilibrium in a closed system?

   • A) The rates of the forward and reverse reactions are equal, so the concentrations of reactants and products remain constant over time.
   • B) The reaction has completely stopped because all reactant molecules have been permanently converted into products.
   • C) The concentrations of all reactants and products must become identical to one another.
   • D) The forward reaction proceeds at a much higher rate than the reverse reaction to keep the products stable.