Roughly what free energy do the electrons carried by NADH hold as they enter the electron transport chain?

1. The electrons passing through the electron transport chain gradually lose energy as they go. 2. Their level of free energy drops from about 60 kcal per mol in NADH. 3. Electrons arriving on the other reduced carrier start lower, at about 45 kcal per mol. 4. By the time they reduce oxygen and form water the level has fallen to about 0 kcal per mol. 5. Answering 45 quotes the starting value for the other carrier rather than for NADH. 6. Answering 0 quotes the end point of the whole chain rather than the entry point. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 7 "Cellular Respiration", section 7.4 Oxidative Phosphorylation_