Worksheet: Types of Equilibrium

In this worksheet, we will practice classifying equilibria as static or dynamic and as homogeneous or heterogeneous.

Q1:

The following reaction occurs when a burner on a gas stove is lit. CH()+2O()CO()+2HO()4222gggg Which of the following statements is an accurate description of this reaction?

  • AAn equilibrium is not established because the rate of the forward reaction is much greater than the rate of the reverse reaction.
  • BAn equilibrium is not established because the reaction is highly exothermic, preventing the temperature from reaching a constant value.
  • CAn equilibrium is not established because the gas stove is not a closed system and the product gases can escape.
  • DAn equilibrium is established because the reaction does not alter the number of moles of gas in the system.
  • EAn equilibrium is established because carbon dioxide and water are already present in the air.

Q2:

If a reaction is reversible, when can it be said to have reached equilibrium?

  • AWhen the reactants and the products have equal concentrations
  • BWhen the concentrations of the reactants and products are equal
  • CWhen the rates of the forward and reverse reactions are equal
  • DWhen the concentrations of the products are equal to the standard value, typically 1 M
  • EWhen the reactants are fully consumed

Q3:

Which of the following is the correct definition of a reversible reaction?

  • AThe forward reaction and the reverse reaction occur at the same rate.
  • BThe reaction can proceed in both the forward and reverse directions.
  • CA second reaction converts the products of the reaction back to reactants, resulting in a cyclic process.
  • DIf you reverse the flow of time, the reaction will undo itself.
  • EThe reaction can be undone with the right catalyst.

Q4:

Under standard conditions, a sealed container of bromine consists of a liquid phase in equilibrium with a gaseous phase. Why would it be impossible to establish an equilibrium between Br()2l and Br()2g if the container were not a closed one?

  • AIn an open system, the rate of condensation is limited by diffusion of Br()2g out of the container.
  • BIn an open system, the container would empty due to rapid vaporization of Br()2l.
  • CIn an open system, it is always more favorable for the material to exist in the gas phase.
  • DIn an open system, the rate of condensation is limited by variation of the boiling point with the liquid mass.
  • EIn an open system, the bromine would be consumed by reaction with air before the phases could equilibrate.

Q5:

At the boiling point of a liquid, which of the following conditions is satisfied?

  • AVapor pressure equals the liquid surface tension.
  • BThe rate of evaporation equals the rate of convection.
  • CThe rate of evaporation equals the rate of condensation.
  • DThe free energies of vaporization and condensation are equal in magnitude.
  • EVapor pressure equals atmospheric pressure.

Q6:

For HO()2s at 0C and 1 atm and HO()2l at 0C and 1 atm, which of the following quantities must be equal for the two phases?

  • AThe molar Gibbs free energy (Gm)
  • BThe molar volume (Vm)
  • CThe molar enthalpy (Hm)
  • DThe molar entropy (Sm)

Q7:

Heat is added to a block of ice in a bath of liquid water at 0C. A student records the temperature of the ice 𝑇 and the mass of liquid water 𝑀. The system remains at thermal equilibrium and ice remains at the end of the process. Which quantities do not change?

  • ABoth 𝑀 and 𝑇
  • BMore information is needed.
  • C 𝑇 only
  • D 𝑀 only
  • ENeither 𝑀 nor 𝑇

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