Question

which statement among a - c is false regarding the redox reactions shown? electron acceptor no2 - + 8h+ + 6e - so4 2 - + 10h+ + 8e - electron donor nh4 + + 2h2o h2s + 4h2o e° (mv)a - 255 + 440 - 220 + 170 δg° (kj) it requires energy to reduce sulfate (so4 2 - ). hydrogen sulfide (h2s) would be considered a strong electron donor. nitrite (no2 - ) is a stronger terminal electron acceptor than sulfate (so4 2 - ). none are false; all are true statements.

Explanation:

Step1: Recall redox - reaction concepts

In redox reactions, a stronger electron donor has a more negative standard reduction potential ($E^0$). A stronger electron acceptor has a more positive standard reduction potential.

Step2: Analyze the given $E^0$ values

For the reaction involving hydrogen sulfide ($H_2S$) as an electron - donor, $E^0=- 220$ mV. For the reaction involving sulfate ($SO_4^{2 - }$) as an electron - acceptor, the related reaction has a different $E^0$ value. For nitrite ($NO_2^{-}$) as an electron - acceptor, its $E^0$ value is also given.

Step3: Evaluate each statement

• Statement 1: It requires energy to reduce sulfate ($SO_4^{2 - }$)

Reduction of sulfate is a non - spontaneous reaction under standard conditions as the electron - donor reactions have negative $E^0$ values relative to the sulfate reduction half - reaction, so energy is required. This statement is true.

• Statement 2: Hydrogen sulfide ($H_2S$) would be considered a strong electron donor

A strong electron donor has a very negative $E^0$ value. Since $E^0$ for $H_2S$ is $-220$ mV, it is a relatively strong electron donor. This statement is true.

• Statement 3: Nitrite ($NO_2^{-}$) is a stronger terminal electron acceptor than sulfate ($SO_4^{2 - }$)

The $E^0$ value for the reduction of $NO_2^{-}$ is more positive than that related to the reduction of $SO_4^{2 - }$, so nitrite is a stronger electron acceptor. This statement is true.

Answer:

None are false; all are true statements.