liambob1 Posted August 4, 2012 Share Posted August 4, 2012 Hey guys, I decided to try and make Benedicts reagent for the lulz. My first step is obtaining Sodium Citrate but I have an issue I hope you can assist me with. I reacted citric acid and sodium bicarbonate to produce sodium citrate water and carbon dioxide. In a moment of stupidity I decided to add ethanol to the product to try and force the salt to precipitate rather than just evaporating off the water. I then attempted to evaporate off the water and ethanol and all was going well till about 80oC when this happened: My theory on this is it is a side reaction involving Fe contamination in the water. I tested the water I used and it was about .02 mg/L Do you think it was an iron side reaction or what else could have happened. The result is a black smelly liquid which I am having a hard time evaporating off because every time I do it erupts like this. Is there a way to rescue my salt? Cheers Link to comment Share on other sites More sharing options...
weiming1998 Posted October 16, 2012 Share Posted October 16, 2012 Firstly, Benedict's reagent doesn't require non-aqueous chemicals. Reacting a known amount citric acid and sodium bicarbonate in stoichiometric quantities will give you sodium citrate in aqueous solution, which you can easily calculate the amount made. Secondly, as I have made Benedict's reagent numerous times, I found that the quantities of chemicals used don't need to be precise. Simply adding excess carbonate solution to citric acid solution, then adding in a bit of copper sulfate made a blue solution that turned brown in the presence of glucose. Finally, apart from iron contamination, the brown-yellow colour can also be partial decomposition of sodium citrate under heat, as organics are very prone to decomposing to a yellowish-brown liquid. Link to comment Share on other sites More sharing options...
paulsutton Posted August 19, 2022 Share Posted August 19, 2022 I am sure you may be able to buy Sodium Citrate, Link to comment Share on other sites More sharing options...
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