MCAT Chemistry Question — Nernst Equation | Next Step Test Prep MCAT Chemistry Question — Nernst Equation | Next Step Test Prep

Fields marked with an * are required

Schedule a Free Tutoring Consultation

A Next Step Academic Manager will contact you within 1 business day or call us now at 888-530-6398.

Contact us

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

The voltage of a galvanic cell, E, depends on the concentration of reactants and products. The Nernst equation,

E = Eo – (0.0592/n)log(Q)

can be used to calculate the cell potential. Eo is the standard cell potential, n is the number of moles of electrons exchanged in the reaction, and Q is the reaction quotient. Which of the following is true regarding the value of E?

 

A. E is always less than Eo

B. E is always greater than Eo

C. E is always equal to Eo

D. E can be less than, greater than, or equal to Eo

 

Explanation

 

According to the Nernst equation, the cell potential E will vary based on the logarithm of the reactant quotient Q. The reactant quotient follows the same equation as the equilibrium constant K, but measures the ratio of the actual concentration of products to concentration of reactants at any time during the reaction. Therefore, when Q > 1, log(Q) is positive and E < Eo. If Q < 1, log(Q) is negative, then E > Eo. Lastly, E is equal to Eo when Q = 1 because the log of one is equal to zero. Thus, E can be less than, greater than, or equal to Eo making D the correct answer.

 

Next Step Test Preparation provides one-on-one MCAT tutor programs nationwide

 

Want more practice?

Fields marked with an * are required

Sign up for our MCAT Question of the Day!

X