Chapter 20, Problem 96A

Interpretation Introduction

Interpretation:

The two half- reactions are to be written.

Concept introduction:

Half cell reactions are of two types:

Oxidation half reaction

Reduction half reaction

Combining these two equations after balancing the electrons forms redox reaction.

Answer to Problem 96A

Oxidation half reaction:

$NADH\to NA{D}^{+}+H^{+}+2e^{-}$

Reduction half reaction:

$O_2+4H^{+}+4e^{-}\to 2H_{2}O$

Explanation of Solution

The overall reaction is:

$2NADH+2H^{+}+O_2\to 2NA{D}^{+}+2H_{2}O$

From table:

$NA{D}^{+}+H^{+}+2e^{-}\to NADH{E}^0=-0.320V$

$O_2+4H^{+}+4e^{-}\to 2H_{2}O{E}^0=0.8147V$

Reduction potential of equation two is more than equation one therefore oxygen is reduced and $NADH$ is oxidized.

Conclusion

Thus, half cell reactions are:

Oxidation half reaction:

$NADH\to NA{D}^{+}+H^{+}+2e^{-}$

Reduction half reaction:

$O_2+4H^{+}+4e^{-}\to 2H_{2}O$