7th edition 6O.3

[paytonm1H]

In 6O.3, it asks to compare various aqueous ion solution to water at pH=7 to see which species will be reduced at the cathode. The answer key uses E=-0.42V for the reduction potential of water. However, in the appendix, the standard reduction potential of water is -0.83V. Can someone explain how they found the other value for pH=7??
Thanks!

[Chloe Qiao 4C]

Under the title "Topic 6O Exercises", it says that for the following questions use E=-0.42 for the reduction of water. I just compared the reduction potential of the ions with that of the water, and the species with higher reduction potential will be reduced.