After about 14.25 hours of soaking, the following was observed:
Hummus with baking soda
Volume after soaking: 20 Oz.
Weight after soaking: 388 gr (original 180).
Water is a little colored (yellowish).
Hummus with no soda (water only)
Volume after soaking: 20 Oz.
Weight after soaking: 396 gr (original 180).
Water is clear.
Initial Conclusion: The addition of soda does not have an effect on the amount of water absorbed through soaking of 14 hours.
Note: weight was determined by pouring off the liquid and tossing the beans to remove liquid water. The beans were still humid on the outside (what is known as saturated surface dry), but not wet.
The beans were covered again with 3 cups of water, with and without baking soda, and left for another day.