If the standard reduction potential of a half reaction is 0.80 V, which statement below is true for this half-reaction to proceed as a reduction A) This half-reaction will proceed if it is coupled to another half-reaction that has a standard reduction potential less than 0.80 V. B) This half-reaction will proceed if it is coupled to another half-reaction that has a standard reduction potential greater than 0.80 V C) This half reaction will proceed if it is coupled to another half-reaction that has a standard reduction potential greater than -0.80 V D) It doesn't matter what half-reaction this is coupled with, it will proceed spontaneously. E) It doesn't matter what half-reaction this is coupled with, it will not proceed spontaneously. subunit of ATP synthase causes conformation changes in the

Answer

The correct is A)

Explanation:

A reduction half-reaction occurs in the cathode. The standard cell potencial (Eºcell) is higher than 0 for a spontaneous reaction. According to this, we deduce:

Eºcell = Eºr(cathode)-Eºr(anode) > 0 (spontaneous)

So, Eºr(cathode) > Eºr(anode) for a spontaneous reaction.

Since Eºr(cathode)= 0.80 V, we can say:

A) This half-reaction will proceed if it is coupled to another half-reaction that has a standard reduction potential less than 0.80 V. TRUE

For example: Eºcell = Eºr(cathode)-Eºr(anode)= 0.80 V - (0.75 V)= 0.05 V > 0

B) This half-reaction will proceed if it is coupled to another half-reaction that has a standard reduction potential greater than 0.80 V. FALSE

It is the opposite of A. For a value greater than 0.80 V, Eºcell will be <0 (non spontaneous)

C) This half reaction will proceed if it is coupled to another half-reaction that has a standard reduction potential greater than -0.80 V. FALSE

This sentence is not true in all cases. For example: a reduction potential of 1.0 V is greater than -0.80 V, so:

Eºcell= Eºr(cathode)-Eºr(anode)= 0.80 V - (1.00 V)= -0.20 V < 0

D) It doesn't matter what half-reaction this is coupled with, it will proceed. FALSE, the reduction potential of the anodic reaction must be lower than 0.80 V.

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.

the correct answer to this question is #5