what does Baking Soda do??

[sh118]

I have seen reccomendations to prewash/soak prefold diapers in the washer with baking soda. What is the goal of this, and how does the baking soda help? I have been doing it, but not sure if it is making a difference.
We have a top load machine, soft water, and I am using Purex free and clear.
Same question regarding vinegar soak. Anyone know the science behind this?

[ExuberantDaffodil]

from what I understand, it acts like a water softener if you have hard water. It can help deodorize & freshen, and also slightly boosts detergent's effectiveness. Its benefits are pretty subtle, though, in my experience.

[sh118]

So it's probably not doing much if I already have soft water? And I'm not adding it to the wash with detergent, just the soak, so not boosting my detergent either. I will stop and see if I can tell the difference.
Thanks.