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: Which of the following statements is an accurate description of this reaction?

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

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

Q3:

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

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

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 B r ( ) 2 l and B r ( ) 2 g if the container were not a closed?

  • AIn an open system, the bromine would be consumed by reaction with air before the phases could equilibrate.
  • BIn an open system, the container would empty due to rapid vaporization of B r ( ) 2 l .
  • 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 diffusion of B r ( ) 2 g out of the container.
  • EIn an open system, the rate of condensation is limited by variation of the boiling point with the liquid mass.

Q5:

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

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

Q6:

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

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

Q7:

Heat is added to a block of ice in a bath of liquid water at 0 C . 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
  • B 𝑀 only
  • CNeither 𝑀 nor 𝑇
  • D 𝑇 only
  • EMore information is needed.

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