Iron-sulfur world theory experiment

[Red Hypergiant]

For my previous science fair, I performed an experiment testing the plausibility of the iron-sulfur world theory. I added ammonia, acetic acid, water, and salt to one container, and heated CaCO3 and zinc in another to create carbon monoxide, which flowed into the first container. The result was lipids and a drop in pH, but I can't seem to get down the cause of this pH drop. Can someone help me?

 

Full details of the experiment here:https://sites.google.com/site/lifefromthedeep/home