Which form of the Nernst equation correctly shows temperature dependence for non-standard conditions?

• A. E = E° + (RT/nF) ln Q
• B. E = E° − (RT/nF) ln Q
• C. E = E° − (F/RT) ln Q
• D. E = E° − (nF/RT) ln Q

Answer: (B)

The Nernst equation shows how the electrode potential under non-standard conditions depends on both the reaction quotient Q and the temperature through the factor RT/nF. At a given temperature, the deviation from the standard potential E° is scaled by RT/(nF) times the natural log of Q, so hotter conditions amplify how sensitive the potential is to the ratio of products to reactants. The form that correctly includes this temperature dependence is E = E° − (RT/(nF)) ln Q. The negative sign means that as Q increases (more products relative to reactants), the reduction potential actually shifts downward, which matches how a system resists reduction when products are favored. E° serves as the baseline at standard conditions, and changing the temperature changes the slope via RT. The other forms mix up the sign or the dimensional factors (for example, using a plus sign, or swapping RT with F, or inverting the RT/factor), which breaks the correct dependence on Q and temperature.