Worksheet: Reaction Profiles

In this worksheet, we will practice reading reaction profile energy diagrams and identifying and describing the energy transfers involved.

Q1:

Shown in the reaction profile are the changes in chemical energy during a reaction.

Energy cannot be created nor destroyed, only changed from one form to another. Which of the following processes is least likely to occur due to the change in chemical energy shown in the figure?

  • A Air molecules above the reaction mixture increase in temperature.
  • B Light is emitted by reacting molecules.
  • C The container for the reaction mixture vibrates less rapidly.
  • D Solvent evaporates from the reaction mixture.
  • E Reactant and product molecules gain kinetic energy.

Q2:

Labelled in the diagram are the chemical energies of three compounds, a–c.

Which of the labelled compounds is highest in energy?

  • A a
  • B c
  • C b

Which of the labelled compounds is lowest in energy?

  • A c
  • B b
  • C a

Which of the labelled compounds is most stable?

  • A c
  • B b
  • C a

Which of the labelled compounds is least stable?

  • A b
  • B c
  • C a

Q3:

Illustrated in the reaction profiles are the changes in chemical energy during a range of processes.

Which of the diagrams best describes the changes in chemical energy for a stick of dynamite during an explosion?

  • A (c)
  • B (a)
  • C (b)

Which of the diagrams best describes the changes in chemical energy for a packet of pasta stored in a kitchen cupboard?

  • A (c)
  • B (b)
  • C (a)

Which of the diagrams best describes the changes in chemical energy for a piece of aluminum being heated by a blowtorch?

  • A (c)
  • B (a)
  • C (b)

Which of the diagrams best describes the changes in chemical energy for a tank of burning petrol?

  • A (b)
  • B (c)
  • C (a)

Q4:

A reaction profile shows the relative energies of chemicals in a chemical reaction.

Shown in the reaction profile are the relative energies of chemicals in a simple chemical reaction.

Which components of a chemical reaction are indicated by A?

  • A Catalysts
  • B Reactants
  • C Products
  • D Transition states
  • E Intermediates

Which components of a chemical reaction are indicated by B?

  • ACatalysts
  • B Products
  • C Transition states
  • D Reactants
  • E Intermediates

Which components have more energy, those at A or those at B?

  • A Those at B have more energy.
  • B Those at A have more energy.

Which components are more stable, those at A or those at B?

  • A Those at B are more stable.
  • B Those at A are more stable.

Would this reaction happen spontaneously?

  • A Yes
  • B More information is needed.
  • C No

Q5:

Illustrated in the reaction profile are the changes in chemical energy during a reaction as the reactant molecules are converted to products.

Based on the reaction profile, is energy absorbed or released during the reaction?

  • AMore information is needed.
  • BAbsorbed
  • CReleased

Q6:

Illustrated in the reaction profile are the changes in chemical energy as reacting molecules are converted to products.

Which of the following is the best description of this chemical reaction?

  • A Energy is absorbed by the reaction and the products are more stable than the reactants.
  • B Energy is absorbed by the reaction and the products are less stable than the reactants.
  • CEnergy is released by the reaction and the products are less stable than the reactants.
  • D Energy is released by the reaction and the products are more stable than the reactants.

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