Worksheet: Reversible and Irreversible Reactions

In this worksheet, we will practice defining reversibility in chemical reactions and identifying examples of reversible and irreversible processes.

Q1:

What is the enthalpy change for the backward reaction according to the data provided in the energy pathway diagram? CuSO()+5HO()CuSO·5HO()4242sls

Q2:

Ammonium chloride decomposes when heated into ammonia gas and hydrogen chloride gas. If the gases are collected and allowed to cool, then ammonium chloride reforms. Which of the following chemical equations describes these changes?

  • ANH()+HCl()NHCl()34ggs
  • BNH()+HCl()NHCl()34ggs
  • CNHCl()NH()+HCl()43sgg
  • DNH()NHCl()+HCl()34gsg
  • ENH()NHCl()+HCl()34gsg

Q3:

Which of the statements do not accurately describe the following chemical reaction? NaCO·10HO()NaCO()+10HO()232232ssg

  • AThe reaction is reversible.
  • BBlue crystals are formed.
  • CAnhydrous sodium carbonate is produced.
  • DThe forward reaction is endothermic.
  • EHO()2g is formed.

Q4:

Which of the following statements about reversible reactions is true?

  • AA reversible reaction is indicated by the symbol → in a chemical equation.
  • BA reversible reaction is endothermic in both directions.
  • CA reversible reaction always involves hydrated and anhydrous salts.
  • DA reversible reaction is often a combustion reaction.
  • EA reversible reaction is a chemical reaction that can proceed in both directions.

Q5:

An alcohol is ignited and a mixture of two different gases is collected. What conclusion could be drawn from this observation?

  • AThe reaction is irreversible.
  • BThe reaction equation would use the symbol ⇌.
  • CThe reaction is endothermic.
  • DThe organic alcohol contains water of crystallization.
  • EThe reaction is reversible.

Q6:

The following reaction can be used as a chemical test for water. CuSO()+5HO()CuSO·5HO()4242sls If the backward reaction is endothermic, what happens when water is added to a test tube containing CuSO()4s?

  • AThe test tube will heat up.
  • BThe test tube will cool down.
  • CThe CuSO()4s will turn pink.
  • DThe CuSO()4s will turn white.
  • ENo reaction will occur.

Q7:

What does the following symbol mean when seen in a chemical equation?

  • AThe reaction is irreversible.
  • BThe reaction is reversible.
  • CThe equation has been written the wrong way around.
  • DThe equation is balanced.

Q8:

When water is added to anhydrous copper (II) sulfate, blue crystals are formed. When these blue crystals are heated, a vapor is observed and a white solid remains.

Chemical reaction

Which of the following statements does not in part explain these observations? CuSO()+5HO()CuSO·5HO()4242sls

  • AThis reaction is reversible.
  • BThis reaction is a neutralization.
  • CThe backward reaction is endothermic.
  • DThe vapor observed is steam, HO()2g.
  • EHydrated copper (II) sulfate contains water of crystallization.

Q9:

In the following chemical reaction, the forward reaction is endothermic. What must be true about the reverse reaction? CuSO·5HO()CuSO()+5HO()4242ssl

  • AThe reverse reaction has a lesser overall energy change.
  • BThe reverse reaction has a greater overall energy change.
  • CThe reverse reaction is also endothermic.
  • DThe reverse reaction is exothermic.
  • EThe reverse reaction absorbs heat from the surroundings.

Q10:

When water is added to yellow nickel (II) chloride powder, it turns green and becomes hot. When heating the green crystals, steam is produced and a yellow solid formed. Which of the following statements describes the crystals of green nickel (II) chloride and the type of reaction that occurs?

  • AGreen nickel (II) chloride is hydrated and the reaction is irreversible.
  • BGreen nickel (II) chloride is aqueous and the reaction is irreversible.
  • CGreen nickel (II) chloride is aqueous and the reaction is reversible.
  • DGreen nickel (II) chloride is hydrated and the reaction is reversible.

Q11:

Which statement about the enthalpy change for the backward reaction in a reversible reaction is true?

  • AThe enthalpy change for the backward reaction is half the amount of the enthalpy change for the forward reaction.
  • BThe enthalpy change for the backward reaction is greater in magnitude than the enthalpy change for the forward reaction.
  • CThe enthalpy change for the backward reaction equals the activation energy plus the enthalpy change for the forward reaction.
  • DThe enthalpy change for the backward reaction is the same in magnitude as the enthalpy change for the forward reaction.
  • EThe enthalpy change for the backward reaction is less in magnitude than the enthalpy change for the forward reaction.

Q12:

What is the backward reaction for the following reversible reaction? CoCl+6HOCoCl·6HO2222

  • ACoCl·6HOCoCl+6H2222
  • BCoCl·6HOCoCl+6HO2222
  • CCoCl+6HOCoCl·6HO2222

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