A particular chemical reaction is exergonic. What can you say about the relationship between the reactants and the products in this exergonic reaction?

Question

A.  The reactants have more free energy than the products
B.  The reactants are likely more disordered and the products are likely more ordered
C.  The reactants cannot spontaneously react to generate the products
D.  The reactants likely have lower enthalpy than the products

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

  Gather Content
  What do you already know about the energy associated with reactants and products in reactions? What other information is related to the question?

  Choose Answer
Do you have all the information needed to answer the question?

  Reflect on Process
  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

A.  The reactants have more free energy than the products


Clarify Question
What is the key concept addressed by the question?
        · The question asks for you to determine the relationship between reactants and products in an exergonic reaction.
What type of thinking is required?
        · You are being asked to take what you already know about enzymes and free energy and apply your understanding to determine the energy characteristics of an exergonic reaction.

  Gather Content
  What do you already know about the energy associated with reactants and products in reactions? What other information is related to the question?
        · To solve this problem you’ll need to apply what you know about the free energy associated with reactants and products and determine how it is associated with exergonic and endergonic reactions. What free energy characteristics determine whether or not a reaction is exergonic (spontaneous) or endergonic (nonspontaneous)?

  Choose Answer
Do you have all the information needed to answer the question?
        · Recall that the change in free energy in enzyme-based reactions is classified as exergonic or endergonic. Exergonic reactions have a negative delta G and are spontaneous, whereas endergonic reactions have a positive delta G and are nonspontaneous. Remember also that nonspontaneous reactions can be made to work if there is sufficient investment of energy (e.g. coupled reactions).
        · The only way to be able to meet the criteria for an exergonic reaction is to choose an answer that will create a negative delta G. In practical terms, that means the free energy of the reactants must be higher than the free energy of the products. All other answer choices are implausible because they violate that basic energy assumption.

  Reflect on Process
  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        · Answering this question correctly depended on your ability to use your understanding of reactions and free energy to determine the energy characteristics for an exergonic reaction.
        · If you got an incorrect answer, did you remember that reactions can be classified as exergonic and endergonic based on whether or not their change in free energy is positive or negative? Did you remember that exergonic reactions have a negative delta G and endergonic reactions have a positive delta G? Were you able to infer from this information that the reactant must have more free energy than the products in order to obtain a negative delta G?