Obuibo, you are right that you can synthesize sodium citrate from citric acid, using baking soda, and the bubbles you are seeing is CO2. it is a 1 to 1 molar ratio of citric acid to baking soda, I can't give you the exact values because that depends on the concentration of the citric acid. I can also tell you that if you are using water as your solvent It is going to take a long time to evaporate it away and you are almost certainly not going to have a pure product. The product SHOULD BE food safe if you are starting with food safe since you will just be neutralizing the citric acid. Hope this helped
